Tag Archives: AWS Step Functions

Orchestrate Multiple ETL Jobs Using AWS Step Functions and AWS Lambda

Post Syndicated from Moataz Anany original https://aws.amazon.com/blogs/big-data/orchestrate-multiple-etl-jobs-using-aws-step-functions-and-aws-lambda/

Extract, transform, and load (ETL) operations collectively form the backbone of any modern enterprise data lake. It transforms raw data into useful datasets and, ultimately, into actionable insight. An ETL job typically reads data from one or more data sources, applies various transformations to the data, and then writes the results to a target where data is ready for consumption. The sources and targets of an ETL job could be relational databases in Amazon Relational Database Service (Amazon RDS) or on-premises, a data warehouse such as Amazon Redshift, or object storage such as Amazon Simple Storage Service (Amazon S3) buckets. Amazon S3 as a target is especially commonplace in the context of building a data lake in AWS.

AWS offers AWS Glue, which is a service that helps author and deploy ETL jobs. AWS Glue is a fully managed extract, transform, and load service that makes it easy for customers to prepare and load their data for analytics. Other AWS Services also can be used to implement and manage ETL jobs. They include: AWS Database Migration Service (AWS DMS), Amazon EMR (using the Steps API), and even Amazon Athena.

The challenge of orchestrating an ETL workflow

How can we orchestrate an ETL workflow that involves a diverse set of ETL technologies? AWS Glue, AWS DMS, Amazon EMR, and other services support Amazon CloudWatch Events, which we could use to chain ETL jobs together. Amazon S3, the central data lake store, also supports CloudWatch Events. But relying on CloudWatch Events alone means that there’s no single visual representation of the ETL workflow. Also, tracing the overall ETL workflow’s execution status and handling error scenarios can become a challenge.

In this post, I show you how to use AWS Step Functions and AWS Lambda for orchestrating multiple ETL jobs involving a diverse set of technologies in an arbitrarily-complex ETL workflow. AWS Step Functions is a web service that enables you to coordinate the components of distributed applications and microservices using visual workflows. You build applications from individual components. Each component performs a discrete function, or task, allowing you to scale and change applications quickly.

Let’s look at an example ETL workflow.

Example datasets for the ETL workflow

For our example, we’ll use two publicly available Amazon QuickSight datasets.

The first dataset is a sales pipeline dataset, which contains a list of slightly more than 20,000 sales opportunity records for a fictitious business. Each record has fields that specify:

  • A date, potentially when an opportunity was identified.
  • The salesperson’s name.
  • A market segment to which the opportunity belongs.
  • Forecasted monthly revenue.

The second dataset is an online marketing metrics dataset. This dataset contains records of marketing metrics, aggregated by day. The metrics describe user engagement across various channels, such as websites, mobile, and social media, plus other marketing metrics. The two datasets are unrelated, but for the purpose of this example we’ll assume that they are related.

The example ETL workflow requirements

Imagine there’s a business user who needs to answer questions based on both datasets. Perhaps the user wants to explore the correlations between online user engagement metrics on the one hand, and forecasted sales revenue and opportunities generated on the other hand. The user engagement metrics include website visits, mobile users, and desktop users.

The steps in the ETL workflow are:

Process the Sales dataset (PSD). Read the Sales dataset. Group records by day, aggregating the Forecasted Monthly Revenue field. Rename fields to replace white space with underscores. Output the intermediary results to Amazon S3 in compressed Parquet format. Overwrite any previous output.

Process the Marketing dataset (PMD). Read the Marketing dataset. Rename fields to replace white space with underscores. Send the intermediary results to Amazon S3 in compressed Parquet format. Overwrite any previous output.

Join Marketing and Sales datasets (JMSD). Read the output of the processed Sales and Marketing datasets. Perform an inner join of both datasets on the date field. Sort in ascending order by date. Send the final joined dataset to Amazon S3, and overwrite any previous output.

So far, this ETL workflow can be implemented with AWS Glue, with the ETL jobs being chained by using job triggers. But you might have other requirements outside of AWS Glue that are part of your end-to-end data processing workflow, such as the following:

  • Both Sales and Marketing datasets are uploaded to an S3 bucket at random times in an interval of up to a week. The PSD job should start as soon as the Sales dataset file is uploaded. The PMD job should start as soon as the Marketing dataset file is uploaded. Parallel ETL jobs can start and finish anytime, but the final JMSD job can start only after all parallel ETL jobs are complete.
  • In addition to PSD and PMD jobs, the orchestration must support more parallel ETL jobs in the future that contribute to the final dataset aggregated by the JMSD job. The additional ETL jobs could be managed by AWS services, such as AWS Database Migration Service, Amazon EMR, Amazon Athena or other non-AWS services.

The data engineer takes these requirements and builds the following ETL workflow chart.

To fulfill the requirements, we need a generic ETL orchestration solution. A serverless solution is even better.

The ETL orchestration architecture and events

Let’s see how we can orchestrate an ETL workflow to fulfill the requirements using AWS Step Functions and AWS Lambda. The following diagram shows the ETL orchestration architecture and the main flow of events.

The main flow of events starts with an AWS Step Functions state machine. This state machine defines the steps in the orchestrated ETL workflow. A state machine can be triggered through Amazon CloudWatch based on a schedule, through the AWS Command Line Interface (AWS CLI), or using the various AWS SDKs in an AWS Lambda function or some other execution environment.

As the state machine execution progresses, it invokes the ETL jobs. As shown in the diagram, the invocation happens indirectly through intermediary AWS Lambda functions that you author and set up in your account. We’ll call this type of function an ETL Runner.

While the architecture in the diagram shows Amazon Athena, Amazon EMR, and AWS Glue, the accompanying code sample (aws-etl-orchestrator) includes a single ETL Runner, labeled AWS Glue Runner Function in the diagram. You can use this ETL Runner to orchestrate AWS Glue jobs. You can also follow the pattern and implement more ETL Runners to orchestrate other AWS services or non-AWS tools.

ETL Runners are invoked by activity tasks in Step Functions. Because of the way AWS Step Functions’ activity tasks work, ETL Runners need to periodically poll the AWS Step Functions state machine for tasks. The state machine responds by providing a Task object. The Task object contains inputs which enable an ETL Runner to run an ETL job.

As soon as an ETL Runner receives a task, it starts the respective ETL job. An ETL Runner maintains a state of active jobs in an Amazon DynamoDB table. Periodically, the ETL Runner checks the status of active jobs. When an active ETL job completes, the ETL Runners notifies the AWS Step Functions state machine. This allows the ETL workflow in AWS Step Functions to proceed to the next step.

An important question may come up. Why does an ETL Runner run independently from your Step Functions state machine and poll for tasks? Can’t we instead directly invoke an AWS Lambda function from the Step Functions state machine? Then can’t we have that function start and monitor an ETL job until it completes?

The answer is that AWS Lambda functions have a maximum execution duration per request of 300 seconds, or 5 minutes. For more information, see AWS Lambda Limits. ETL jobs typically take more than 5 minutes to complete. If an ETL Runner function is invoked directly, it will likely time out before the ETL job completes. Thus, we follow the long-running worker approach with activity tasks. The worker in this code sample – the ETL Runner – is an AWS Lambda function that gets triggered on a schedule using CloudWatch Events. If you want to avoid managing the polling schedule through CloudWatch Events, you can implement a polling loop in your ETL workflow’s state machine. Check the AWS Big Data blog post Orchestrate Apache Spark applications using AWS Step Functions and Apache Livy for an example.

Finally, let’s discuss how we fulfill the requirement of waiting for Sales and Marketing datasets to arrive in an S3 bucket at random times. We implement these waits as two separate activity tasks: Wait for Sales Data and Wait for Marketing Data. A state machine halts execution when it encounters either of these activity tasks. A CloudWatch Events event handler is then configured on an Amazon S3 bucket, so that when Sales or Marketing dataset files are uploaded to the bucket, Amazon S3 invokes an AWS Lambda function. The Lambda function then signals the waiting state machine to exit the activity task corresponding to the uploaded dataset. The subsequent ETL job is then invoked by the state machine.

Set up your own ETL orchestration

The aws-etl-orchestrator GitHub repository provides source code you can customize to set up the ETL orchestration architecture in your AWS account. The following steps show what you need to do to start orchestrating your ETL jobs using the architecture shown in this post:

  1. Model the ETL orchestration workflow in AWS Step Functions
  2. Build your ETL Runners (or use an existing AWS Glue ETL Runner)
  3. Customize AWS CloudFormation templates and create stacks
  4. Invoke the ETL orchestration state machine
  5. Upload sample Sales and Marketing datasets to Amazon S3

Model the ETL orchestration workflow in AWS Step Functions.  Use AWS Step Functions to model the ETL workflow described in this post as a state machine. A state machine in Step Functions consists of a set of states and the transitions between these states. A state machine is defined in Amazon States Language, which is a JSON-based notation. For a few examples of state machine definitions, see Sample Projects.

The following snapshot from the AWS Step Functions console shows our example ETL workflow modeled as a state machine. This workflow is what we provide you in the code sample.

When you start an execution of this state machine, it will branch to run two ETL jobs in parallel: Process Sales Data (PSD) and Process Marketing Data (PMD). But, according to the requirements, both ETL jobs should not start until their respective datasets are uploaded to Amazon S3. Hence, we implement Wait activity tasks before both PSD and PMD. When a dataset file is uploaded to Amazon S3, this triggers an AWS Lambda function that notifies the state machine to exit the Wait states. When both PMD and PSD jobs are successful, the JMSD job runs to produce the final dataset.

Finally, to have this ETL workflow execute once per week, you will need to configure a state machine execution to start once per week using a CloudWatch Event.

Build your ETL Runners (or use an existing AWS Glue ETL Runner)The code sample includes an AWS Glue ETL Runner. For simplicity, we implemented the ETL workflow using only AWS Glue jobs. However, nothing prevents you from using a different ETL technology to implement PMD or PSD jobs. You’ll need to build an ETL Runner for the technology that follows the AWS Glue ETL Runner example.

Customize AWS CloudFormation templates and create stacks. The sample published in the aws-etl-orchestrator repository includes three separate AWS CloudFormation templates. We organized resources into three templates following AWS CloudFormation best practices. The three resource groups are logically distinct and likely to have separate lifecycles and ownerships. Each template has an associated AWS CloudFormation parameters file (“*-params.json” files). Parameters in those files must be customized. The details about the three AWS CloudFormation templates are as follows:

  1. A template responsible for setting up AWS Glue resources.For our example ETL workflow, the sample template creates three AWS Glue jobs: PSD, PMD, and JMSD. The scripts for these jobs are pulled by AWS CloudFormation from an Amazon S3 bucket that you own.
  2. A template where the AWS Step Functions state machine is defined.The state machine definition in Amazon States Language is embedded in a StateMachine resource within the Step Functions template.
  3. A template that sets up resources required by the ETL Runner for AWS Glue.The AWS Glue ETL Runner is a Python script that is written to be run as an AWS Lambda function.

Invoke the ETL orchestration state machine. Finally, it is time to start a new state machine execution in AWS Step Functions. For our ETL example, the AWS CloudFormation template creates a state machine named MarketingAndSalesETLOrchestrator. You can start an execution from the AWS Step Functions console, or through an AWS CLI command. When you start an execution, the state machine will immediately enter Wait for Data states, waiting for datasets to be uploaded to Amazon S3.

Upload sample Sales and Marketing datasets to Amazon S3

Upload datasets provided to the S3 bucket that you specified in the code sample configuration. This uploaded datasets signal the state machine to continue execution.

The state machine may take a while to complete execution. You can monitor progress in the AWS Step Functions console. If the execution is successful, the output shown in the following diagram appears.

Congratulations! You’ve orchestrated the example ETL workflow to a successful completion.

Handling failed ETL jobs

What if a job in the ETL workflow fails? In such a case, there are error-handling strategies available to the ETL workflow developer, from simply notifying an administrator, to fully undoing the effects of the previous jobs through compensating ETL jobs. Detecting and responding to a failed ETL job can be implemented using the AWS Step Functions’ Catch mechanism. For more information, see Handling Error Conditions Using a State Machine. In the sample state machine, errors are handled by a do-nothing Pass state.

Try it out. Stop any of the example ETL workflow’s jobs while executing through the AWS Glue console or the AWS CLI. You’ll notice the state machine transitioning to the ETL Job Failed Fallback state.

Conclusion

In this post, I showed you how to implement your ETL logic as an orchestrated workflow. I presented a serverless solution for ETL orchestration that allows you to control ETL job execution using AWS Step Functions and AWS Lambda.  You can use the concepts and the code described in this post to build arbitrarily complex ETL state machines.

For more information and to download the source code, see the aws-etl-orchestrator GitHub repository. If you have questions about this post, send them our way in the Comments section below.


Additional Reading

If you found this post useful, be sure to check out Build a Data Lake Foundation with AWS Glue and Amazon S3 and Orchestrate Apache Spark applications using AWS Step Functions and Apache Livy.

 


About the Author

Moataz Anany is a senior solutions architect with AWS. He enjoys partnering with customers to help them leverage AWS and the cloud in creative ways. He dedicates most of his spare time to his wife and little ones. The rest is spent building and breaking things in side projects.

 

 

 

 

EU Compliance Update: AWS’s 2017 C5 Assessment

Post Syndicated from Oliver Bell original https://aws.amazon.com/blogs/security/eu-compliance-update-awss-2017-c5-assessment/

C5 logo

AWS has completed its 2017 assessment against the Cloud Computing Compliance Controls Catalog (C5) information security and compliance program. Bundesamt für Sicherheit in der Informationstechnik (BSI)—Germany’s national cybersecurity authority—established C5 to define a reference standard for German cloud security requirements. With C5 (as well as with IT-Grundschutz), customers in German member states can use the work performed under this BSI audit to comply with stringent local requirements and operate secure workloads in the AWS Cloud.

Continuing our commitment to Germany and the AWS European Regions, AWS has added 16 services to this year’s scope:

The English version of the C5 report is available through AWS Artifact. The German version of the report will be available through AWS Artifact in the coming weeks.

– Oliver

Serverless @ re:Invent 2017

Post Syndicated from Chris Munns original https://aws.amazon.com/blogs/compute/serverless-reinvent-2017/

At re:Invent 2014, we announced AWS Lambda, what is now the center of the serverless platform at AWS, and helped ignite the trend of companies building serverless applications.

This year, at re:Invent 2017, the topic of serverless was everywhere. We were incredibly excited to see the energy from everyone attending 7 workshops, 15 chalk talks, 20 skills sessions and 27 breakout sessions. Many of these sessions were repeated due to high demand, so we are happy to summarize and provide links to the recordings and slides of these sessions.

Over the course of the week leading up to and then the week of re:Invent, we also had over 15 new features and capabilities across a number of serverless services, including AWS Lambda, Amazon API Gateway, AWS [email protected], AWS SAM, and the newly announced AWS Serverless Application Repository!

AWS Lambda

Amazon API Gateway

  • Amazon API Gateway Supports Endpoint Integrations with Private VPCs – You can now provide access to HTTP(S) resources within your VPC without exposing them directly to the public internet. This includes resources available over a VPN or Direct Connect connection!
  • Amazon API Gateway Supports Canary Release Deployments – You can now use canary release deployments to gradually roll out new APIs. This helps you more safely roll out API changes and limit the blast radius of new deployments.
  • Amazon API Gateway Supports Access Logging – The access logging feature lets you generate access logs in different formats such as CLF (Common Log Format), JSON, XML, and CSV. The access logs can be fed into your existing analytics or log processing tools so you can perform more in-depth analysis or take action in response to the log data.
  • Amazon API Gateway Customize Integration Timeouts – You can now set a custom timeout for your API calls as low as 50ms and as high as 29 seconds (the default is 30 seconds).
  • Amazon API Gateway Supports Generating SDK in Ruby – This is in addition to support for SDKs in Java, JavaScript, Android and iOS (Swift and Objective-C). The SDKs that Amazon API Gateway generates save you development time and come with a number of prebuilt capabilities, such as working with API keys, exponential back, and exception handling.

AWS Serverless Application Repository

Serverless Application Repository is a new service (currently in preview) that aids in the publication, discovery, and deployment of serverless applications. With it you’ll be able to find shared serverless applications that you can launch in your account, while also sharing ones that you’ve created for others to do the same.

AWS [email protected]

[email protected] now supports content-based dynamic origin selection, network calls from viewer events, and advanced response generation. This combination of capabilities greatly increases the use cases for [email protected], such as allowing you to send requests to different origins based on request information, showing selective content based on authentication, and dynamically watermarking images for each viewer.

AWS SAM

Twitch Launchpad live announcements

Other service announcements

Here are some of the other highlights that you might have missed. We think these could help you make great applications:

AWS re:Invent 2017 sessions

Coming up with the right mix of talks for an event like this can be quite a challenge. The Product, Marketing, and Developer Advocacy teams for Serverless at AWS spent weeks reading through dozens of talk ideas to boil it down to the final list.

From feedback at other AWS events and webinars, we knew that customers were looking for talks that focused on concrete examples of solving problems with serverless, how to perform common tasks such as deployment, CI/CD, monitoring, and troubleshooting, and to see customer and partner examples solving real world problems. To that extent we tried to settle on a good mix based on attendee experience and provide a track full of rich content.

Below are the recordings and slides of breakout sessions from re:Invent 2017. We’ve organized them for those getting started, those who are already beginning to build serverless applications, and the experts out there already running them at scale. Some of the videos and slides haven’t been posted yet, and so we will update this list as they become available.

Find the entire Serverless Track playlist on YouTube.

Talks for people new to Serverless

Advanced topics

Expert mode

Talks for specific use cases

Talks from AWS customers & partners

Looking to get hands-on with Serverless?

At re:Invent, we delivered instructor-led skills sessions to help attendees new to serverless applications get started quickly. The content from these sessions is already online and you can do the hands-on labs yourself!
Build a Serverless web application

Still looking for more?

We also recently completely overhauled the main Serverless landing page for AWS. This includes a new Resources page containing case studies, webinars, whitepapers, customer stories, reference architectures, and even more Getting Started tutorials. Check it out!

AWS Updated Its ISO Certifications and Now Has 67 Services Under ISO Compliance

Post Syndicated from Chad Woolf original https://aws.amazon.com/blogs/security/aws-updated-its-iso-certifications-and-now-has-67-services-under-iso-compliance/

ISO logo

AWS has updated its certifications against ISO 9001, ISO 27001, ISO 27017, and ISO 27018 standards, bringing the total to 67 services now under ISO compliance. We added the following 29 services this cycle:

Amazon Aurora Amazon S3 Transfer Acceleration AWS [email protected]
Amazon Cloud Directory Amazon SageMaker AWS Managed Services
Amazon CloudWatch Logs Amazon Simple Notification Service AWS OpsWorks Stacks
Amazon Cognito Auto Scaling AWS Shield
Amazon Connect AWS Batch AWS Snowball Edge
Amazon Elastic Container Registry AWS CodeBuild AWS Snowmobile
Amazon Inspector AWS CodeCommit AWS Step Functions
Amazon Kinesis Data Streams AWS CodeDeploy AWS Systems Manager (formerly Amazon EC2 Systems Manager)
Amazon Macie AWS CodePipeline AWS X-Ray
Amazon QuickSight AWS IoT Core

For the complete list of services under ISO compliance, see AWS Services in Scope by Compliance Program.

AWS maintains certifications through extensive audits of its controls to ensure that information security risks that affect the confidentiality, integrity, and availability of company and customer information are appropriately managed.

You can download copies of the AWS ISO certificates that contain AWS’s in-scope services and Regions, and use these certificates to jump-start your own certification efforts:

AWS does not increase service costs in any AWS Region as a result of updating its certifications.

To learn more about compliance in the AWS Cloud, see AWS Cloud Compliance.

– Chad

Implementing Dynamic ETL Pipelines Using AWS Step Functions

Post Syndicated from Tara Van Unen original https://aws.amazon.com/blogs/compute/implementing-dynamic-etl-pipelines-using-aws-step-functions/

This post contributed by:
Wangechi Dole, AWS Solutions Architect
Milan Krasnansky, ING, Digital Solutions Developer, SGK
Rian Mookencherry, Director – Product Innovation, SGK

Data processing and transformation is a common use case you see in our customer case studies and success stories. Often, customers deal with complex data from a variety of sources that needs to be transformed and customized through a series of steps to make it useful to different systems and stakeholders. This can be difficult due to the ever-increasing volume, velocity, and variety of data. Today, data management challenges cannot be solved with traditional databases.

Workflow automation helps you build solutions that are repeatable, scalable, and reliable. You can use AWS Step Functions for this. A great example is how SGK used Step Functions to automate the ETL processes for their client. With Step Functions, SGK has been able to automate changes within the data management system, substantially reducing the time required for data processing.

In this post, SGK shares the details of how they used Step Functions to build a robust data processing system based on highly configurable business transformation rules for ETL processes.

SGK: Building dynamic ETL pipelines

SGK is a subsidiary of Matthews International Corporation, a diversified organization focusing on brand solutions and industrial technologies. SGK’s Global Content Creation Studio network creates compelling content and solutions that connect brands and products to consumers through multiple assets including photography, video, and copywriting.

We were recently contracted to build a sophisticated and scalable data management system for one of our clients. We chose to build the solution on AWS to leverage advanced, managed services that help to improve the speed and agility of development.

The data management system served two main functions:

  1. Ingesting a large amount of complex data to facilitate both reporting and product funding decisions for the client’s global marketing and supply chain organizations.
  2. Processing the data through normalization and applying complex algorithms and data transformations. The system goal was to provide information in the relevant context—such as strategic marketing, supply chain, product planning, etc. —to the end consumer through automated data feeds or updates to existing ETL systems.

We were faced with several challenges:

  • Output data that needed to be refreshed at least twice a day to provide fresh datasets to both local and global markets. That constant data refresh posed several challenges, especially around data management and replication across multiple databases.
  • The complexity of reporting business rules that needed to be updated on a constant basis.
  • Data that could not be processed as contiguous blocks of typical time-series data. The measurement of the data was done across seasons (that is, combination of dates), which often resulted with up to three overlapping seasons at any given time.
  • Input data that came from 10+ different data sources. Each data source ranged from 1–20K rows with as many as 85 columns per input source.

These challenges meant that our small Dev team heavily invested time in frequent configuration changes to the system and data integrity verification to make sure that everything was operating properly. Maintaining this system proved to be a daunting task and that’s when we turned to Step Functions—along with other AWS services—to automate our ETL processes.

Solution overview

Our solution included the following AWS services:

  • AWS Step Functions: Before Step Functions was available, we were using multiple Lambda functions for this use case and running into memory limit issues. With Step Functions, we can execute steps in parallel simultaneously, in a cost-efficient manner, without running into memory limitations.
  • AWS Lambda: The Step Functions state machine uses Lambda functions to implement the Task states. Our Lambda functions are implemented in Java 8.
  • Amazon DynamoDB provides us with an easy and flexible way to manage business rules. We specify our rules as Keys. These are key-value pairs stored in a DynamoDB table.
  • Amazon RDS: Our ETL pipelines consume source data from our RDS MySQL database.
  • Amazon Redshift: We use Amazon Redshift for reporting purposes because it integrates with our BI tools. Currently we are using Tableau for reporting which integrates well with Amazon Redshift.
  • Amazon S3: We store our raw input files and intermediate results in S3 buckets.
  • Amazon CloudWatch Events: Our users expect results at a specific time. We use CloudWatch Events to trigger Step Functions on an automated schedule.

Solution architecture

This solution uses a declarative approach to defining business transformation rules that are applied by the underlying Step Functions state machine as data moves from RDS to Amazon Redshift. An S3 bucket is used to store intermediate results. A CloudWatch Event rule triggers the Step Functions state machine on a schedule. The following diagram illustrates our architecture:

Here are more details for the above diagram:

  1. A rule in CloudWatch Events triggers the state machine execution on an automated schedule.
  2. The state machine invokes the first Lambda function.
  3. The Lambda function deletes all existing records in Amazon Redshift. Depending on the dataset, the Lambda function can create a new table in Amazon Redshift to hold the data.
  4. The same Lambda function then retrieves Keys from a DynamoDB table. Keys represent specific marketing campaigns or seasons and map to specific records in RDS.
  5. The state machine executes the second Lambda function using the Keys from DynamoDB.
  6. The second Lambda function retrieves the referenced dataset from RDS. The records retrieved represent the entire dataset needed for a specific marketing campaign.
  7. The second Lambda function executes in parallel for each Key retrieved from DynamoDB and stores the output in CSV format temporarily in S3.
  8. Finally, the Lambda function uploads the data into Amazon Redshift.

To understand the above data processing workflow, take a closer look at the Step Functions state machine for this example.

We walk you through the state machine in more detail in the following sections.

Walkthrough

To get started, you need to:

  • Create a schedule in CloudWatch Events
  • Specify conditions for RDS data extracts
  • Create Amazon Redshift input files
  • Load data into Amazon Redshift

Step 1: Create a schedule in CloudWatch Events
Create rules in CloudWatch Events to trigger the Step Functions state machine on an automated schedule. The following is an example cron expression to automate your schedule:

In this example, the cron expression invokes the Step Functions state machine at 3:00am and 2:00pm (UTC) every day.

Step 2: Specify conditions for RDS data extracts
We use DynamoDB to store Keys that determine which rows of data to extract from our RDS MySQL database. An example Key is MCS2017, which stands for, Marketing Campaign Spring 2017. Each campaign has a specific start and end date and the corresponding dataset is stored in RDS MySQL. A record in RDS contains about 600 columns, and each Key can represent up to 20K records.

A given day can have multiple campaigns with different start and end dates running simultaneously. In the following example DynamoDB item, three campaigns are specified for the given date.

The state machine example shown above uses Keys 31, 32, and 33 in the first ChoiceState and Keys 21 and 22 in the second ChoiceState. These keys represent marketing campaigns for a given day. For example, on Monday, there are only two campaigns requested. The ChoiceState with Keys 21 and 22 is executed. If three campaigns are requested on Tuesday, for example, then ChoiceState with Keys 31, 32, and 33 is executed. MCS2017 can be represented by Key 21 and Key 33 on Monday and Tuesday, respectively. This approach gives us the flexibility to add or remove campaigns dynamically.

Step 3: Create Amazon Redshift input files
When the state machine begins execution, the first Lambda function is invoked as the resource for FirstState, represented in the Step Functions state machine as follows:

"Comment": ” AWS Amazon States Language.", 
  "StartAt": "FirstState",
 
"States": { 
  "FirstState": {
   
"Type": "Task",
   
"Resource": "arn:aws:lambda:xx-xxxx-x:XXXXXXXXXXXX:function:Start",
    "Next": "ChoiceState" 
  } 

As described in the solution architecture, the purpose of this Lambda function is to delete existing data in Amazon Redshift and retrieve keys from DynamoDB. In our use case, we found that deleting existing records was more efficient and less time-consuming than finding the delta and updating existing records. On average, an Amazon Redshift table can contain about 36 million cells, which translates to roughly 65K records. The following is the code snippet for the first Lambda function in Java 8:

public class LambdaFunctionHandler implements RequestHandler<Map<String,Object>,Map<String,String>> {
    Map<String,String> keys= new HashMap<>();
    public Map<String, String> handleRequest(Map<String, Object> input, Context context){
       Properties config = getConfig(); 
       // 1. Cleaning Redshift Database
       new RedshiftDataService(config).cleaningTable(); 
       // 2. Reading data from Dynamodb
       List<String> keyList = new DynamoDBDataService(config).getCurrentKeys();
       for(int i = 0; i < keyList.size(); i++) {
           keys.put(”key" + (i+1), keyList.get(i)); 
       }
       keys.put(”key" + T,String.valueOf(keyList.size()));
       // 3. Returning the key values and the key count from the “for” loop
       return (keys);
}

The following JSON represents ChoiceState.

"ChoiceState": {
   "Type" : "Choice",
   "Choices": [ 
   {

      "Variable": "$.keyT",
     "StringEquals": "3",
     "Next": "CurrentThreeKeys" 
   }, 
   {

     "Variable": "$.keyT",
    "StringEquals": "2",
    "Next": "CurrentTwooKeys" 
   } 
 ], 
 "Default": "DefaultState"
}

The variable $.keyT represents the number of keys retrieved from DynamoDB. This variable determines which of the parallel branches should be executed. At the time of publication, Step Functions does not support dynamic parallel state. Therefore, choices under ChoiceState are manually created and assigned hardcoded StringEquals values. These values represent the number of parallel executions for the second Lambda function.

For example, if $.keyT equals 3, the second Lambda function is executed three times in parallel with keys, $key1, $key2 and $key3 retrieved from DynamoDB. Similarly, if $.keyT equals two, the second Lambda function is executed twice in parallel.  The following JSON represents this parallel execution:

"CurrentThreeKeys": { 
  "Type": "Parallel",
  "Next": "NextState",
  "Branches": [ 
  {

     "StartAt": “key31",
    "States": { 
       “key31": {

          "Type": "Task",
        "InputPath": "$.key1",
        "Resource": "arn:aws:lambda:xx-xxxx-x:XXXXXXXXXXXX:function:Execution",
        "End": true 
       } 
    } 
  }, 
  {

     "StartAt": “key32",
    "States": { 
     “key32": {

        "Type": "Task",
       "InputPath": "$.key2",
         "Resource": "arn:aws:lambda:xx-xxxx-x:XXXXXXXXXXXX:function:Execution",
       "End": true 
      } 
     } 
   }, 
   {

      "StartAt": “key33",
       "States": { 
          “key33": {

                "Type": "Task",
             "InputPath": "$.key3",
             "Resource": "arn:aws:lambda:xx-xxxx-x:XXXXXXXXXXXX:function:Execution",
           "End": true 
       } 
     } 
    } 
  ] 
} 

Step 4: Load data into Amazon Redshift
The second Lambda function in the state machine extracts records from RDS associated with keys retrieved for DynamoDB. It processes the data then loads into an Amazon Redshift table. The following is code snippet for the second Lambda function in Java 8.

public class LambdaFunctionHandler implements RequestHandler<String, String> {
 public static String key = null;

public String handleRequest(String input, Context context) { 
   key=input; 
   //1. Getting basic configurations for the next classes + s3 client Properties
   config = getConfig();

   AmazonS3 s3 = AmazonS3ClientBuilder.defaultClient(); 
   // 2. Export query results from RDS into S3 bucket 
   new RdsDataService(config).exportDataToS3(s3,key); 
   // 3. Import query results from S3 bucket into Redshift 
    new RedshiftDataService(config).importDataFromS3(s3,key); 
   System.out.println(input); 
   return "SUCCESS"; 
 } 
}

After the data is loaded into Amazon Redshift, end users can visualize it using their preferred business intelligence tools.

Lessons learned

  • At the time of publication, the 1.5–GB memory hard limit for Lambda functions was inadequate for processing our complex workload. Step Functions gave us the flexibility to chunk our large datasets and process them in parallel, saving on costs and time.
  • In our previous implementation, we assigned each key a dedicated Lambda function along with CloudWatch rules for schedule automation. This approach proved to be inefficient and quickly became an operational burden. Previously, we processed each key sequentially, with each key adding about five minutes to the overall processing time. For example, processing three keys meant that the total processing time was three times longer. With Step Functions, the entire state machine executes in about five minutes.
  • Using DynamoDB with Step Functions gave us the flexibility to manage keys efficiently. In our previous implementations, keys were hardcoded in Lambda functions, which became difficult to manage due to frequent updates. DynamoDB is a great way to store dynamic data that changes frequently, and it works perfectly with our serverless architectures.

Conclusion

With Step Functions, we were able to fully automate the frequent configuration updates to our dataset resulting in significant cost savings, reduced risk to data errors due to system downtime, and more time for us to focus on new product development rather than support related issues. We hope that you have found the information useful and that it can serve as a jump-start to building your own ETL processes on AWS with managed AWS services.

For more information about how Step Functions makes it easy to coordinate the components of distributed applications and microservices in any workflow, see the use case examples and then build your first state machine in under five minutes in the Step Functions console.

If you have questions or suggestions, please comment below.

Implementing Canary Deployments of AWS Lambda Functions with Alias Traffic Shifting

Post Syndicated from Chris Munns original https://aws.amazon.com/blogs/compute/implementing-canary-deployments-of-aws-lambda-functions-with-alias-traffic-shifting/

This post courtesy of Ryan Green, Software Development Engineer, AWS Serverless

The concepts of blue/green and canary deployments have been around for a while now and have been well-established as best-practices for reducing the risk of software deployments.

In a traditional, horizontally scaled application, copies of the application code are deployed to multiple nodes (instances, containers, on-premises servers, etc.), typically behind a load balancer. In these applications, deploying new versions of software to too many nodes at the same time can impact application availability as there may not be enough healthy nodes to service requests during the deployment. This aggressive approach to deployments also drastically increases the blast radius of software bugs introduced in the new version and does not typically give adequate time to safely assess the quality of the new version against production traffic.

In such applications, one commonly accepted solution to these problems is to slowly and incrementally roll out application software across the nodes in the fleet while simultaneously verifying application health (canary deployments). Another solution is to stand up an entirely different fleet and weight (or flip) traffic over to the new fleet after verification, ideally with some production traffic (blue/green). Some teams deploy to a single host (“one box environment”), where the new release can bake for some time before promotion to the rest of the fleet. Techniques like this enable the maintainers of complex systems to safely test in production while minimizing customer impact.

Enter Serverless

There is somewhat of an impedance mismatch when mapping these concepts to a serverless world. You can’t incrementally deploy your software across a fleet of servers when there are no servers!* In fact, even the term “deployment” takes on a different meaning with functions as a service (FaaS). In AWS Lambda, a “deployment” can be roughly modeled as a call to CreateFunction, UpdateFunctionCode, or UpdateAlias (I won’t get into the semantics of whether updating configuration counts as a deployment), all of which may affect the version of code that is invoked by clients.

The abstractions provided by Lambda remove the need for developers to be concerned about servers and Availability Zones, and this provides a powerful opportunity to greatly simplify the process of deploying software.
*Of course there are servers, but they are abstracted away from the developer.

Traffic shifting with Lambda aliases

Before the release of traffic shifting for Lambda aliases, deployments of a Lambda function could only be performed in a single “flip” by updating function code for version $LATEST, or by updating an alias to target a different function version. After the update propagates, typically within a few seconds, 100% of function invocations execute the new version. Implementing canary deployments with this model required the development of an additional routing layer, further adding development time, complexity, and invocation latency.
While rolling back a bad deployment of a Lambda function is a trivial operation and takes effect near instantaneously, deployments of new versions for critical functions can still be a potentially nerve-racking experience.

With the introduction of alias traffic shifting, it is now possible to trivially implement canary deployments of Lambda functions. By updating additional version weights on an alias, invocation traffic is routed to the new function versions based on the weight specified. Detailed CloudWatch metrics for the alias and version can be analyzed during the deployment, or other health checks performed, to ensure that the new version is healthy before proceeding.

Note: Sometimes the term “canary deployments” refers to the release of software to a subset of users. In the case of alias traffic shifting, the new version is released to some percentage of all users. It’s not possible to shard based on identity without adding an additional routing layer.

Examples

The simplest possible use of a canary deployment looks like the following:

# Update $LATEST version of function
aws lambda update-function-code --function-name myfunction ….

# Publish new version of function
aws lambda publish-version --function-name myfunction

# Point alias to new version, weighted at 5% (original version at 95% of traffic)
aws lambda update-alias --function-name myfunction --name myalias --routing-config '{"AdditionalVersionWeights" : {"2" : 0.05} }'

# Verify that the new version is healthy
…
# Set the primary version on the alias to the new version and reset the additional versions (100% weighted)
aws lambda update-alias --function-name myfunction --name myalias --function-version 2 --routing-config '{}'

This is begging to be automated! Here are a few options.

Simple deployment automation

This simple Python script runs as a Lambda function and deploys another function (how meta!) by incrementally increasing the weight of the new function version over a prescribed number of steps, while checking the health of the new version. If the health check fails, the alias is rolled back to its initial version. The health check is implemented as a simple check against the existence of Errors metrics in CloudWatch for the alias and new version.

GitHub aws-lambda-deploy repo

Install:

git clone https://github.com/awslabs/aws-lambda-deploy
cd aws-lambda-deploy
export BUCKET_NAME=[YOUR_S3_BUCKET_NAME_FOR_BUILD_ARTIFACTS]
./install.sh

Run:

# Rollout version 2 incrementally over 10 steps, with 120s between each step
aws lambda invoke --function-name SimpleDeployFunction --log-type Tail --payload \
  '{"function-name": "MyFunction",
  "alias-name": "MyAlias",
  "new-version": "2",
  "steps": 10,
  "interval" : 120,
  "type": "linear"
  }' output

Description of input parameters

  • function-name: The name of the Lambda function to deploy
  • alias-name: The name of the alias used to invoke the Lambda function
  • new-version: The version identifier for the new version to deploy
  • steps: The number of times the new version weight is increased
  • interval: The amount of time (in seconds) to wait between weight updates
  • type: The function to use to generate the weights. Supported values: “linear”

Because this runs as a Lambda function, it is subject to the maximum timeout of 5 minutes. This may be acceptable for many use cases, but to achieve a slower rollout of the new version, a different solution is required.

Step Functions workflow

This state machine performs essentially the same task as the simple deployment function, but it runs as an asynchronous workflow in AWS Step Functions. A nice property of Step Functions is that the maximum deployment timeout has now increased from 5 minutes to 1 year!

The step function incrementally updates the new version weight based on the steps parameter, waiting for some time based on the interval parameter, and performing health checks between updates. If the health check fails, the alias is rolled back to the original version and the workflow fails.

For example, to execute the workflow:

export STATE_MACHINE_ARN=`aws cloudformation describe-stack-resources --stack-name aws-lambda-deploy-stack --logical-resource-id DeployStateMachine --output text | cut  -d$'\t' -f3`

aws stepfunctions start-execution --state-machine-arn $STATE_MACHINE_ARN --input '{
  "function-name": "MyFunction",
  "alias-name": "MyAlias",
  "new-version": "2",
  "steps": 10,
  "interval": 120,
  "type": "linear"}'

Getting feedback on the deployment

Because the state machine runs asynchronously, retrieving feedback on the deployment requires polling for the execution status using DescribeExecution or implementing an asynchronous notification (using SNS or email, for example) from the Rollback or Finalize functions. A CloudWatch alarm could also be created to alarm based on the “ExecutionsFailed” metric for the state machine.

A note on health checks and observability

Weighted rollouts like this are considerably more successful if the code is being exercised and monitored continuously. In this example, it would help to have some automation continuously invoking the alias and reporting metrics on these invocations, such as client-side success rates and latencies.

The absence of Lambda Errors metrics used in these examples can be misleading if the function is not getting invoked. It’s also recommended to instrument your Lambda functions with custom metrics, in addition to Lambda’s built-in metrics, that can be used to monitor health during deployments.

Extensibility

These examples could be easily extended in various ways to support different use cases. For example:

  • Health check implementations: CloudWatch alarms, automatic invocations with payload assertions, querying external systems, etc.
  • Weight increase functions: Exponential, geometric progression, single canary step, etc.
  • Custom success/failure notifications: SNS, email, CI/CD systems, service discovery systems, etc.

Traffic shifting with SAM and CodeDeploy

Using the Lambda UpdateAlias operation with additional version weights provides a powerful primitive for you to implement custom traffic shifting solutions for Lambda functions.

For those not interested in building custom deployment solutions, AWS CodeDeploy provides an intuitive turn-key implementation of this functionality integrated directly into the Serverless Application Model. Traffic-shifted deployments can be declared in a SAM template, and CodeDeploy manages the function rollout as part of the CloudFormation stack update. CloudWatch alarms can also be configured to trigger a stack rollback if something goes wrong.

i.e.

MyFunction:
  Type: AWS::Serverless::Function
  Properties:
    FunctionName: MyFunction
    AutoPublishAlias: MyFunctionInvokeAlias
    DeploymentPreference:
      Type: Linear10PercentEvery1Minute
      Role:
        Fn::GetAtt: [ DeploymentRole, Arn ]
      Alarms:
       - { Ref: MyFunctionErrorsAlarm }
...

For more information about using CodeDeploy with SAM, see Automating Updates to Serverless Apps.

Conclusion

It is often the simple features that provide the most value. As I demonstrated in this post, serverless architectures allow the complex deployment orchestration used in traditional applications to be replaced with a simple Lambda function or Step Functions workflow. By allowing invocation traffic to be easily weighted to multiple function versions, Lambda alias traffic shifting provides a simple but powerful feature that I hope empowers you to easily implement safe deployment workflows for your Lambda functions.

Serverless Automated Cost Controls, Part1

Post Syndicated from Shankar Ramachandran original https://aws.amazon.com/blogs/compute/serverless-automated-cost-controls-part1/

This post courtesy of Shankar Ramachandran, Pubali Sen, and George Mao

In line with AWS’s continual efforts to reduce costs for customers, this series focuses on how customers can build serverless automated cost controls. This post provides an architecture blueprint and a sample implementation to prevent budget overruns.

This solution uses the following AWS products:

  • AWS Budgets – An AWS Cost Management tool that helps customers define and track budgets for AWS costs, and forecast for up to three months.
  • Amazon SNS – An AWS service that makes it easy to set up, operate, and send notifications from the cloud.
  • AWS Lambda – An AWS service that lets you run code without provisioning or managing servers.

You can fine-tune a budget for various parameters, for example filtering by service or tag. The Budgets tool lets you post notifications on an SNS topic. A Lambda function that subscribes to the SNS topic can act on the notification. Any programmatically implementable action can be taken.

The diagram below describes the architecture blueprint.

In this post, we describe how to use this blueprint with AWS Step Functions and IAM to effectively revoke the ability of a user to start new Amazon EC2 instances, after a budget amount is exceeded.

Freedom with guardrails

AWS lets you quickly spin up resources as you need them, deploying hundreds or even thousands of servers in minutes. This means you can quickly develop and roll out new applications. Teams can experiment and innovate more quickly and frequently. If an experiment fails, you can always de-provision those servers without risk.

This improved agility also brings in the need for effective cost controls. Your Finance and Accounting department must budget, monitor, and control the AWS spend. For example, this could be a budget per project. Further, Finance and Accounting must take appropriate actions if the budget for the project has been exceeded, for example. Call it “freedom with guardrails” – where Finance wants to give developers freedom, but with financial constraints.

Architecture

This section describes how to use the blueprint introduced earlier to implement a “freedom with guardrails” solution.

  1. The budget for “Project Beta” is set up in Budgets. In this example, we focus on EC2 usage and identify the instances that belong to this project by filtering on the tag Project with the value Beta. For more information, see Creating a Budget.
  2. The budget configuration also includes settings to send a notification on an SNS topic when the usage exceeds 100% of the budgeted amount. For more information, see Creating an Amazon SNS Topic for Budget Notifications.
  3. The master Lambda function receives the SNS notification.
  4. It triggers execution of a Step Functions state machine with the parameters for completing the configured action.
  5. The action Lambda function is triggered as a task in the state machine. The function interacts with IAM to effectively remove the user’s permissions to create an EC2 instance.

This decoupled modular design allows for extensibility.  New actions (serially or in parallel) can be added by simply adding new steps.

Implementing the solution

All the instructions and code needed to implement the architecture have been posted on the Serverless Automated Cost Controls GitHub repo. We recommend that you try this first in a Dev/Test environment.

This implementation description can be broken down into two parts:

  1. Create a solution stack for serverless automated cost controls.
  2. Verify the solution by testing the EC2 fleet.

To tie this back to the “freedom with guardrails” scenario, the Finance department performs a one-time implementation of the solution stack. To simulate resources for Project Beta, the developers spin up the test EC2 fleet.

Prerequisites

There are two prerequisites:

  • Make sure that you have the necessary IAM permissions. For more information, see the section titled “Required IAM permissions” in the README.
  • Define and activate a cost allocation tag with the key Project. For more information, see Using Cost Allocation Tags. It can take up to 12 hours for the tags to propagate to Budgets.

Create resources

The solution stack includes creating the following resources:

  • Three Lambda functions
  • One Step Functions state machine
  • One SNS topic
  • One IAM group
  • One IAM user
  • IAM policies as needed
  • One budget

Two of the Lambda functions were described in the previous section, to a) receive the SNS notification and b) trigger the Step Functions state machine. Another Lambda function is used to create the budget, as a custom AWS CloudFormation resource. The SNS topic connects Budgets with Lambda function A. Lambda function B is configured as a task in Step Functions. A budget for $2 is created which is filtered by Service: EC2 and Tag: Project, Beta. A test IAM group and user is created to enable you to validate this Cost Control Solution.

To create the serverless automated cost control solution stack, choose the button below. It takes few minutes to spin up the stack. You can monitor the progress in the CloudFormation console.

When you see the CREATE_COMPLETE status for the stack you had created, choose Outputs. Copy the following four values that you need later:

  • TemplateURL
  • UserName
  • SignInURL
  • Password

Verify the stack

The next step is to verify the serverless automated cost controls solution stack that you just created. To do this, spin up an EC2 fleet of t2.micro instances, representative of the resources needed for Project Beta, and tag them with Project, Beta.

  1. Browse to the SignInURL, and log in using the UserName and Password values copied on from the stack output.
  2. In the CloudFormation console, choose Create Stack.
  3. For Choose a template, select Choose an Amazon S3 template URL and paste the TemplateURL value from the preceding section. Choose Next.
  4. Give this stack a name, such as “testEc2FleetForProjectBeta”. Choose Next.
  5. On the Specify Details page, enter parameters such as the UserName and Password copied in the previous section. Choose Next.
  6. Ignore any errors related to listing IAM roles. The test user has a minimal set of permissions that is just sufficient to spin up this test stack (in line with security best practices).
  7. On the Options page, choose Next.
  8. On the Review page, choose Create. It takes a few minutes to spin up the stack, and you can monitor the progress in the CloudFormation console. 
  9. When you see the status “CREATE_COMPLETE”, open the EC2 console to verify that four t2.micro instances have been spun up, with the tag of Project, Beta.

The hourly cost for these instances depends on the region in which they are running. On the average (irrespective of the region), you can expect the aggregate cost for this EC2 fleet to exceed the set $2 budget in 48 hours.

Verify the solution

The first step is to identify the test IAM group that was created in the previous section. The group should have “projectBeta” in the name, prepended with the CloudFormation stack name and appended with an alphanumeric string. Verify that the managed policy associated is: “EC2FullAccess”, which indicates that the users in this group have unrestricted access to EC2.

There are two stages of verification for this serverless automated cost controls solution: simulating a notification and waiting for a breach.

Simulated notification

Because it takes at least a few hours for the aggregate cost of the EC2 fleet to breach the set budget, you can verify the solution by simulating the notification from Budgets.

  1. Log in to the SNS console (using your regular AWS credentials).
  2. Publish a message on the SNS topic that has “budgetNotificationTopic” in the name. The complete name is appended by the CloudFormation stack identifier.  
  3. Copy the following text as the body of the notification: “This is a mock notification”.
  4. Choose Publish.
  5. Open the IAM console to verify that the policy for the test group has been switched to “EC2ReadOnly”. This prevents users in this group from creating new instances.
  6. Verify that the test user created in the previous section cannot spin up new EC2 instances.  You can log in as the test user and try creating a new EC2 instance (via the same CloudFormation stack or the EC2 console). You should get an error message indicating that you do not have the necessary permissions.
  7. If you are proceeding to stage 2 of the verification, then you must switch the permissions back to “EC2FullAccess” for the test group, which can be done in the IAM console.

Automatic notification

Within 48 hours, the aggregate cost of the EC2 fleet spun up in the earlier section breaches the budget rule and triggers an automatic notification. This results in the permissions getting switched out, just as in the simulated notification.

Clean up

Use the following steps to delete your resources and stop incurring costs.

  1. Open the CloudFormation console.
  2. Delete the EC2 fleet by deleting the appropriate stack (for example, delete the stack named “testEc2FleetForProjectBeta”).                                               
  3. Next, delete the “costControlStack” stack.                                                                                                                                                    

Conclusion

Using Lambda in tandem with Budgets, you can build Serverless automated cost controls on AWS. Find all the resources (instructions, code) for implementing the solution discussed in this post on the Serverless Automated Cost Controls GitHub repo.

Stay tuned to this series for more tips about building serverless automated cost controls. In the next post, we discuss using smart lighting to influence developer behavior and describe a solution to encourage cost-aware development practices.

If you have questions or suggestions, please comment below.

 

Resume AWS Step Functions from Any State

Post Syndicated from Andy Katz original https://aws.amazon.com/blogs/compute/resume-aws-step-functions-from-any-state/


Yash Pant, Solutions Architect, AWS


Aaron Friedman, Partner Solutions Architect, AWS

When we discuss how to build applications with customers, we often align to the Well Architected Framework pillars of security, reliability, performance efficiency, cost optimization, and operational excellence. Designing for failure is an essential component to developing well architected applications that are resilient to spurious errors that may occur.

There are many ways you can use AWS services to achieve high availability and resiliency of your applications. For example, you can couple Elastic Load Balancing with Auto Scaling and Amazon EC2 instances to build highly available applications. Or use Amazon API Gateway and AWS Lambda to rapidly scale out a microservices-based architecture. Many AWS services have built in solutions to help with the appropriate error handling, such as Dead Letter Queues (DLQ) for Amazon SQS or retries in AWS Batch.

AWS Step Functions is an AWS service that makes it easy for you to coordinate the components of distributed applications and microservices. Step Functions allows you to easily design for failure, by incorporating features such as error retries and custom error handling from AWS Lambda exceptions. These features allow you to programmatically handle many common error modes and build robust, reliable applications.

In some rare cases, however, your application may fail in an unexpected manner. In these situations, you might not want to duplicate in a repeat execution those portions of your state machine that have already run. This is especially true when orchestrating long-running jobs or executing a complex state machine as part of a microservice. Here, you need to know the last successful state in your state machine from which to resume, so that you don’t duplicate previous work. In this post, we present a solution to enable you to resume from any given state in your state machine in the case of an unexpected failure.

Resuming from a given state

To resume a failed state machine execution from the state at which it failed, you first run a script that dynamically creates a new state machine. When the new state machine is executed, it resumes the failed execution from the point of failure. The script contains the following two primary steps:

  1. Parse the execution history of the failed execution to find the name of the state at which it failed, as well as the JSON input to that state.
  2. Create a new state machine, which adds an additional state to failed state machine, called "GoToState". "GoToState" is a choice state at the beginning of the state machine that branches execution directly to the failed state, allowing you to skip states that had succeeded in the previous execution.

The full script along with a CloudFormation template that creates a demo of this is available in the aws-sfn-resume-from-any-state GitHub repo.

Diving into the script

In this section, we walk you through the script and highlight the core components of its functionality. The script contains a main function, which adds a command line parameter for the failedExecutionArn so that you can easily call the script from the command line:

python gotostate.py --failedExecutionArn '<Failed_Execution_Arn>'

Identifying the failed state in your execution

First, the script extracts the name of the failed state along with the input to that state. It does so by using the failed state machine execution history, which is identified by the Amazon Resource Name (ARN) of the execution. The failed state is marked in the execution history, along with the input to that state (which is also the output of the preceding successful state). The script is able to parse these values from the log.

The script loops through the execution history of the failed state machine, and traces it backwards until it finds the failed state. If the state machine failed in a parallel state, then it must restart from the beginning of the parallel state. The script is able to capture the name of the parallel state that failed, rather than any substate within the parallel state that may have caused the failure. The following code is the Python function that does this.


def parseFailureHistory(failedExecutionArn):

    '''
    Parses the execution history of a failed state machine to get the name of failed state and the input to the failed state:
    Input failedExecutionArn = A string containing the execution ARN of a failed state machine y
    Output = A list with two elements: [name of failed state, input to failed state]
    '''
    failedAtParallelState = False
    try:
        #Get the execution history
        response = client.get\_execution\_history(
            executionArn=failedExecutionArn,
            reverseOrder=True
        )
        failedEvents = response['events']
    except Exception as ex:
        raise ex
    #Confirm that the execution actually failed, raise exception if it didn't fail.
    try:
        failedEvents[0]['executionFailedEventDetails']
    except:
        raise('Execution did not fail')
        
    '''
    If you have a 'States.Runtime' error (for example, if a task state in your state machine attempts to execute a Lambda function in a different region than the state machine), get the ID of the failed state, and use it to determine the failed state name and input.
    '''
    
    if failedEvents[0]['executionFailedEventDetails']['error'] == 'States.Runtime':
        failedId = int(filter(str.isdigit, str(failedEvents[0]['executionFailedEventDetails']['cause'].split()[13])))
        failedState = failedEvents[-1 \* failedId]['stateEnteredEventDetails']['name']
        failedInput = failedEvents[-1 \* failedId]['stateEnteredEventDetails']['input']
        return (failedState, failedInput)
        
    '''
    You need to loop through the execution history, tracing back the executed steps.
    The first state you encounter is the failed state. If you failed on a parallel state, you need the name of the parallel state rather than the name of a state within a parallel state that it failed on. This is because you can only attach goToState to the parallel state, but not a substate within the parallel state.
    This loop starts with the ID of the latest event and uses the previous event IDs to trace back the execution to the beginning (id 0). However, it returns as soon it finds the name of the failed state.
    '''

    currentEventId = failedEvents[0]['id']
    while currentEventId != 0:
        #multiply event ID by -1 for indexing because you're looking at the reversed history
        currentEvent = failedEvents[-1 \* currentEventId]
        
        '''
        You can determine if the failed state was a parallel state because it and an event with 'type'='ParallelStateFailed' appears in the execution history before the name of the failed state
        '''

        if currentEvent['type'] == 'ParallelStateFailed':
            failedAtParallelState = True

        '''
        If the failed state is not a parallel state, then the name of failed state to return is the name of the state in the first 'TaskStateEntered' event type you run into when tracing back the execution history
        '''

        if currentEvent['type'] == 'TaskStateEntered' and failedAtParallelState == False:
            failedState = currentEvent['stateEnteredEventDetails']['name']
            failedInput = currentEvent['stateEnteredEventDetails']['input']
            return (failedState, failedInput)

        '''
        If the failed state was a parallel state, then you need to trace execution back to the first event with 'type'='ParallelStateEntered', and return the name of the state
        '''

        if currentEvent['type'] == 'ParallelStateEntered' and failedAtParallelState:
            failedState = failedState = currentEvent['stateEnteredEventDetails']['name']
            failedInput = currentEvent['stateEnteredEventDetails']['input']
            return (failedState, failedInput)
        #Update the ID for the next execution of the loop
        currentEventId = currentEvent['previousEventId']
        

Create the new state machine

The script uses the name of the failed state to create the new state machine, with "GoToState" branching execution directly to the failed state.

To do this, the script requires the Amazon States Language (ASL) definition of the failed state machine. It modifies the definition to append "GoToState", and create a new state machine from it.

The script gets the ARN of the failed state machine from the execution ARN of the failed state machine. This ARN allows it to get the ASL definition of the failed state machine by calling the DesribeStateMachine API action. It creates a new state machine with "GoToState".

When the script creates the new state machine, it also adds an additional input variable called "resuming". When you execute this new state machine, you specify this resuming variable as true in the input JSON. This tells "GoToState" to branch execution to the state that had previously failed. Here’s the function that does this:

def attachGoToState(failedStateName, stateMachineArn):

    '''
    Given a state machine ARN and the name of a state in that state machine, create a new state machine that starts at a new choice state called 'GoToState'. "GoToState" branches to the named state, and sends the input of the state machine to that state, when a variable called "resuming" is set to True.
    Input failedStateName = A string with the name of the failed state
          stateMachineArn = A string with the ARN of the state machine
    Output response from the create_state_machine call, which is the API call that creates a new state machine
    '''

    try:
        response = client.describe\_state\_machine(
            stateMachineArn=stateMachineArn
        )
    except:
        raise('Could not get ASL definition of state machine')
    roleArn = response['roleArn']
    stateMachine = json.loads(response['definition'])
    #Create a name for the new state machine
    newName = response['name'] + '-with-GoToState'
    #Get the StartAt state for the original state machine, because you point the 'GoToState' to this state
    originalStartAt = stateMachine['StartAt']

    '''
    Create the GoToState with the variable $.resuming.
    If new state machine is executed with $.resuming = True, then the state machine skips to the failed state.
    Otherwise, it executes the state machine from the original start state.
    '''

    goToState = {'Type':'Choice', 'Choices':[{'Variable':'$.resuming', 'BooleanEquals':False, 'Next':originalStartAt}], 'Default':failedStateName}
    #Add GoToState to the set of states in the new state machine
    stateMachine['States']['GoToState'] = goToState
    #Add StartAt
    stateMachine['StartAt'] = 'GoToState'
    #Create new state machine
    try:
        response = client.create_state_machine(
            name=newName,
            definition=json.dumps(stateMachine),
            roleArn=roleArn
        )
    except:
        raise('Failed to create new state machine with GoToState')
    return response

Testing the script

Now that you understand how the script works, you can test it out.

The following screenshot shows an example state machine that has failed, called "TestMachine". This state machine successfully completed "FirstState" and "ChoiceState", but when it branched to "FirstMatchState", it failed.

Use the script to create a new state machine that allows you to rerun this state machine, but skip the "FirstState" and the "ChoiceState" steps that already succeeded. You can do this by calling the script as follows:

python gotostate.py --failedExecutionArn 'arn:aws:states:us-west-2:<AWS_ACCOUNT_ID>:execution:TestMachine-with-GoToState:b2578403-f41d-a2c7-e70c-7500045288595

This creates a new state machine called "TestMachine-with-GoToState", and returns its ARN, along with the input that had been sent to "FirstMatchState". You can then inspect the input to determine what caused the error. In this case, you notice that the input to "FirstMachState" was the following:

{
"foo": 1,
"Message": true
}

However, this state machine expects the "Message" field of the JSON to be a string rather than a Boolean. Execute the new "TestMachine-with-GoToState" state machine, change the input to be a string, and add the "resuming" variable that "GoToState" requires:

{
"foo": 1,
"Message": "Hello!",
"resuming":true
}

When you execute the new state machine, it skips "FirstState" and "ChoiceState", and goes directly to "FirstMatchState", which was the state that failed:

Look at what happens when you have a state machine with multiple parallel steps. This example is included in the GitHub repository associated with this post. The repo contains a CloudFormation template that sets up this state machine and provides instructions to replicate this solution.

The following state machine, "ParallelStateMachine", takes an input through two subsequent parallel states before doing some final processing and exiting, along with the JSON with the ASL definition of the state machine.

{
  "Comment": "An example of the Amazon States Language using a parallel state to execute two branches at the same time.",
  "StartAt": "Parallel",
  "States": {
    "Parallel": {
      "Type": "Parallel",
      "ResultPath":"$.output",
      "Next": "Parallel 2",
      "Branches": [
        {
          "StartAt": "Parallel Step 1, Process 1",
          "States": {
            "Parallel Step 1, Process 1": {
              "Type": "Task",
              "Resource": "arn:aws:lambda:us-west-2:XXXXXXXXXXXX:function:LambdaA",
              "End": true
            }
          }
        },
        {
          "StartAt": "Parallel Step 1, Process 2",
          "States": {
            "Parallel Step 1, Process 2": {
              "Type": "Task",
              "Resource": "arn:aws:lambda:us-west-2:XXXXXXXXXXXX:function:LambdaA",
              "End": true
            }
          }
        }
      ]
    },
    "Parallel 2": {
      "Type": "Parallel",
      "Next": "Final Processing",
      "Branches": [
        {
          "StartAt": "Parallel Step 2, Process 1",
          "States": {
            "Parallel Step 2, Process 1": {
              "Type": "Task",
              "Resource": "arn:aws:lambda:us-west-2:XXXXXXXXXXXXX:function:LambdaB",
              "End": true
            }
          }
        },
        {
          "StartAt": "Parallel Step 2, Process 2",
          "States": {
            "Parallel Step 2, Process 2": {
              "Type": "Task",
              "Resource": "arn:aws:lambda:us-west-2:XXXXXXXXXXXX:function:LambdaB",
              "End": true
            }
          }
        }
      ]
    },
    "Final Processing": {
      "Type": "Task",
      "Resource": "arn:aws:lambda:us-west-2:XXXXXXXXXXXX:function:LambdaC",
      "End": true
    }
  }
}

First, use an input that initially fails:

{
  "Message": "Hello!"
}

This fails because the state machine expects you to have a variable in the input JSON called "foo" in the second parallel state to run "Parallel Step 2, Process 1" and "Parallel Step 2, Process 2". Instead, the original input gets processed by the first parallel state and produces the following output to pass to the second parallel state:

{
"output": [
    {
      "Message": "Hello!"
    },
    {
      "Message": "Hello!"
    }
  ],
}

Run the script on the failed state machine to create a new state machine that allows it to resume directly at the second parallel state instead of having to redo the first parallel state. This creates a new state machine called "ParallelStateMachine-with-GoToState". The following JSON was created by the script to define the new state machine in ASL. It contains the "GoToState" value that was attached by the script.

{
   "Comment":"An example of the Amazon States Language using a parallel state to execute two branches at the same time.",
   "States":{
      "Final Processing":{
         "Resource":"arn:aws:lambda:us-west-2:XXXXXXXXXXXX:function:LambdaC",
         "End":true,
         "Type":"Task"
      },
      "GoToState":{
         "Default":"Parallel 2",
         "Type":"Choice",
         "Choices":[
            {
               "Variable":"$.resuming",
               "BooleanEquals":false,
               "Next":"Parallel"
            }
         ]
      },
      "Parallel":{
         "Branches":[
            {
               "States":{
                  "Parallel Step 1, Process 1":{
                     "Resource":"arn:aws:lambda:us-west-2:XXXXXXXXXXXX:function:LambdaA",
                     "End":true,
                     "Type":"Task"
                  }
               },
               "StartAt":"Parallel Step 1, Process 1"
            },
            {
               "States":{
                  "Parallel Step 1, Process 2":{
                     "Resource":"arn:aws:lambda:us-west-2:XXXXXXXXXXXX:LambdaA",
                     "End":true,
                     "Type":"Task"
                  }
               },
               "StartAt":"Parallel Step 1, Process 2"
            }
         ],
         "ResultPath":"$.output",
         "Type":"Parallel",
         "Next":"Parallel 2"
      },
      "Parallel 2":{
         "Branches":[
            {
               "States":{
                  "Parallel Step 2, Process 1":{
                     "Resource":"arn:aws:lambda:us-west-2:XXXXXXXXXXXX:function:LambdaB",
                     "End":true,
                     "Type":"Task"
                  }
               },
               "StartAt":"Parallel Step 2, Process 1"
            },
            {
               "States":{
                  "Parallel Step 2, Process 2":{
                     "Resource":"arn:aws:lambda:us-west-2:XXXXXXXXXXXX:function:LambdaB",
                     "End":true,
                     "Type":"Task"
                  }
               },
               "StartAt":"Parallel Step 2, Process 2"
            }
         ],
         "Type":"Parallel",
         "Next":"Final Processing"
      }
   },
   "StartAt":"GoToState"
}

You can then execute this state machine with the correct input by adding the "foo" and "resuming" variables:

{
  "foo": 1,
  "output": [
    {
      "Message": "Hello!"
    },
    {
      "Message": "Hello!"
    }
  ],
  "resuming": true
}

This yields the following result. Notice that this time, the state machine executed successfully to completion, and skipped the steps that had previously failed.


Conclusion

When you’re building out complex workflows, it’s important to be prepared for failure. You can do this by taking advantage of features such as automatic error retries in Step Functions and custom error handling of Lambda exceptions.

Nevertheless, state machines still have the possibility of failing. With the methodology and script presented in this post, you can resume a failed state machine from its point of failure. This allows you to skip the execution of steps in the workflow that had already succeeded, and recover the process from the point of failure.

To see more examples, please visit the Step Functions Getting Started page.

If you have questions or suggestions, please comment below.

Event-Driven Computing with Amazon SNS and AWS Compute, Storage, Database, and Networking Services

Post Syndicated from Christie Gifrin original https://aws.amazon.com/blogs/compute/event-driven-computing-with-amazon-sns-compute-storage-database-and-networking-services/

Contributed by Otavio Ferreira, Manager, Software Development, AWS Messaging

Like other developers around the world, you may be tackling increasingly complex business problems. A key success factor, in that case, is the ability to break down a large project scope into smaller, more manageable components. A service-oriented architecture guides you toward designing systems as a collection of loosely coupled, independently scaled, and highly reusable services. Microservices take this even further. To improve performance and scalability, they promote fine-grained interfaces and lightweight protocols.

However, the communication among isolated microservices can be challenging. Services are often deployed onto independent servers and don’t share any compute or storage resources. Also, you should avoid hard dependencies among microservices, to preserve maintainability and reusability.

If you apply the pub/sub design pattern, you can effortlessly decouple and independently scale out your microservices and serverless architectures. A pub/sub messaging service, such as Amazon SNS, promotes event-driven computing that statically decouples event publishers from subscribers, while dynamically allowing for the exchange of messages between them. An event-driven architecture also introduces the responsiveness needed to deal with complex problems, which are often unpredictable and asynchronous.

What is event-driven computing?

Given the context of microservices, event-driven computing is a model in which subscriber services automatically perform work in response to events triggered by publisher services. This paradigm can be applied to automate workflows while decoupling the services that collectively and independently work to fulfil these workflows. Amazon SNS is an event-driven computing hub, in the AWS Cloud, that has native integration with several AWS publisher and subscriber services.

Which AWS services publish events to SNS natively?

Several AWS services have been integrated as SNS publishers and, therefore, can natively trigger event-driven computing for a variety of use cases. In this post, I specifically cover AWS compute, storage, database, and networking services, as depicted below.

Compute services

  • Auto Scaling: Helps you ensure that you have the correct number of Amazon EC2 instances available to handle the load for your application. You can configure Auto Scaling lifecycle hooks to trigger events, as Auto Scaling resizes your EC2 cluster.As an example, you may want to warm up the local cache store on newly launched EC2 instances, and also download log files from other EC2 instances that are about to be terminated. To make this happen, set an SNS topic as your Auto Scaling group’s notification target, then subscribe two Lambda functions to this SNS topic. The first function is responsible for handling scale-out events (to warm up cache upon provisioning), whereas the second is in charge of handling scale-in events (to download logs upon termination).

  • AWS Elastic Beanstalk: An easy-to-use service for deploying and scaling web applications and web services developed in a number of programming languages. You can configure event notifications for your Elastic Beanstalk environment so that notable events can be automatically published to an SNS topic, then pushed to topic subscribers.As an example, you may use this event-driven architecture to coordinate your continuous integration pipeline (such as Jenkins CI). That way, whenever an environment is created, Elastic Beanstalk publishes this event to an SNS topic, which triggers a subscribing Lambda function, which then kicks off a CI job against your newly created Elastic Beanstalk environment.

  • Elastic Load Balancing: Automatically distributes incoming application traffic across Amazon EC2 instances, containers, or other resources identified by IP addresses.You can configure CloudWatch alarms on Elastic Load Balancing metrics, to automate the handling of events derived from Classic Load Balancers. As an example, you may leverage this event-driven design to automate latency profiling in an Amazon ECS cluster behind a Classic Load Balancer. In this example, whenever your ECS cluster breaches your load balancer latency threshold, an event is posted by CloudWatch to an SNS topic, which then triggers a subscribing Lambda function. This function runs a task on your ECS cluster to trigger a latency profiling tool, hosted on the cluster itself. This can enhance your latency troubleshooting exercise by making it timely.

Storage services

  • Amazon S3: Object storage built to store and retrieve any amount of data.You can enable S3 event notifications, and automatically get them posted to SNS topics, to automate a variety of workflows. For instance, imagine that you have an S3 bucket to store incoming resumes from candidates, and a fleet of EC2 instances to encode these resumes from their original format (such as Word or text) into a portable format (such as PDF).In this example, whenever new files are uploaded to your input bucket, S3 publishes these events to an SNS topic, which in turn pushes these messages into subscribing SQS queues. Then, encoding workers running on EC2 instances poll these messages from the SQS queues; retrieve the original files from the input S3 bucket; encode them into PDF; and finally store them in an output S3 bucket.

  • Amazon EFS: Provides simple and scalable file storage, for use with Amazon EC2 instances, in the AWS Cloud.You can configure CloudWatch alarms on EFS metrics, to automate the management of your EFS systems. For example, consider a highly parallelized genomics analysis application that runs against an EFS system. By default, this file system is instantiated on the “General Purpose” performance mode. Although this performance mode allows for lower latency, it might eventually impose a scaling bottleneck. Therefore, you may leverage an event-driven design to handle it automatically.Basically, as soon as the EFS metric “Percent I/O Limit” breaches 95%, CloudWatch could post this event to an SNS topic, which in turn would push this message into a subscribing Lambda function. This function automatically creates a new file system, this time on the “Max I/O” performance mode, then switches the genomics analysis application to this new file system. As a result, your application starts experiencing higher I/O throughput rates.

  • Amazon Glacier: A secure, durable, and low-cost cloud storage service for data archiving and long-term backup.You can set a notification configuration on an Amazon Glacier vault so that when a job completes, a message is published to an SNS topic. Retrieving an archive from Amazon Glacier is a two-step asynchronous operation, in which you first initiate a job, and then download the output after the job completes. Therefore, SNS helps you eliminate polling your Amazon Glacier vault to check whether your job has been completed, or not. As usual, you may subscribe SQS queues, Lambda functions, and HTTP endpoints to your SNS topic, to be notified when your Amazon Glacier job is done.

  • AWS Snowball: A petabyte-scale data transport solution that uses secure appliances to transfer large amounts of data.You can leverage Snowball notifications to automate workflows related to importing data into and exporting data from AWS. More specifically, whenever your Snowball job status changes, Snowball can publish this event to an SNS topic, which in turn can broadcast the event to all its subscribers.As an example, imagine a Geographic Information System (GIS) that distributes high-resolution satellite images to users via Web browser. In this example, the GIS vendor could capture up to 80 TB of satellite images; create a Snowball job to import these files from an on-premises system to an S3 bucket; and provide an SNS topic ARN to be notified upon job status changes in Snowball. After Snowball changes the job status from “Importing” to “Completed”, Snowball publishes this event to the specified SNS topic, which delivers this message to a subscribing Lambda function, which finally creates a CloudFront web distribution for the target S3 bucket, to serve the images to end users.

Database services

  • Amazon RDS: Makes it easy to set up, operate, and scale a relational database in the cloud.RDS leverages SNS to broadcast notifications when RDS events occur. As usual, these notifications can be delivered via any protocol supported by SNS, including SQS queues, Lambda functions, and HTTP endpoints.As an example, imagine that you own a social network website that has experienced organic growth, and needs to scale its compute and database resources on demand. In this case, you could provide an SNS topic to listen to RDS DB instance events. When the “Low Storage” event is published to the topic, SNS pushes this event to a subscribing Lambda function, which in turn leverages the RDS API to increase the storage capacity allocated to your DB instance. The provisioning itself takes place within the specified DB maintenance window.

  • Amazon ElastiCache: A web service that makes it easy to deploy, operate, and scale an in-memory data store or cache in the cloud.ElastiCache can publish messages using Amazon SNS when significant events happen on your cache cluster. This feature can be used to refresh the list of servers on client machines connected to individual cache node endpoints of a cache cluster. For instance, an ecommerce website fetches product details from a cache cluster, with the goal of offloading a relational database and speeding up page load times. Ideally, you want to make sure that each web server always has an updated list of cache servers to which to connect.To automate this node discovery process, you can get your ElastiCache cluster to publish events to an SNS topic. Thus, when ElastiCache event “AddCacheNodeComplete” is published, your topic then pushes this event to all subscribing HTTP endpoints that serve your ecommerce website, so that these HTTP servers can update their list of cache nodes.

  • Amazon Redshift: A fully managed data warehouse that makes it simple to analyze data using standard SQL and BI (Business Intelligence) tools.Amazon Redshift uses SNS to broadcast relevant events so that data warehouse workflows can be automated. As an example, imagine a news website that sends clickstream data to a Kinesis Firehose stream, which then loads the data into Amazon Redshift, so that popular news and reading preferences might be surfaced on a BI tool. At some point though, this Amazon Redshift cluster might need to be resized, and the cluster enters a ready-only mode. Hence, this Amazon Redshift event is published to an SNS topic, which delivers this event to a subscribing Lambda function, which finally deletes the corresponding Kinesis Firehose delivery stream, so that clickstream data uploads can be put on hold.At a later point, after Amazon Redshift publishes the event that the maintenance window has been closed, SNS notifies a subscribing Lambda function accordingly, so that this function can re-create the Kinesis Firehose delivery stream, and resume clickstream data uploads to Amazon Redshift.

  • AWS DMS: Helps you migrate databases to AWS quickly and securely. The source database remains fully operational during the migration, minimizing downtime to applications that rely on the database.DMS also uses SNS to provide notifications when DMS events occur, which can automate database migration workflows. As an example, you might create data replication tasks to migrate an on-premises MS SQL database, composed of multiple tables, to MySQL. Thus, if replication tasks fail due to incompatible data encoding in the source tables, these events can be published to an SNS topic, which can push these messages into a subscribing SQS queue. Then, encoders running on EC2 can poll these messages from the SQS queue, encode the source tables into a compatible character set, and restart the corresponding replication tasks in DMS. This is an event-driven approach to a self-healing database migration process.

Networking services

  • Amazon Route 53: A highly available and scalable cloud-based DNS (Domain Name System). Route 53 health checks monitor the health and performance of your web applications, web servers, and other resources.You can set CloudWatch alarms and get automated Amazon SNS notifications when the status of your Route 53 health check changes. As an example, imagine an online payment gateway that reports the health of its platform to merchants worldwide, via a status page. This page is hosted on EC2 and fetches platform health data from DynamoDB. In this case, you could configure a CloudWatch alarm for your Route 53 health check, so that when the alarm threshold is breached, and the payment gateway is no longer considered healthy, then CloudWatch publishes this event to an SNS topic, which pushes this message to a subscribing Lambda function, which finally updates the DynamoDB table that populates the status page. This event-driven approach avoids any kind of manual update to the status page visited by merchants.

  • AWS Direct Connect (AWS DX): Makes it easy to establish a dedicated network connection from your premises to AWS, which can reduce your network costs, increase bandwidth throughput, and provide a more consistent network experience than Internet-based connections.You can monitor physical DX connections using CloudWatch alarms, and send SNS messages when alarms change their status. As an example, when a DX connection state shifts to 0 (zero), indicating that the connection is down, this event can be published to an SNS topic, which can fan out this message to impacted servers through HTTP endpoints, so that they might reroute their traffic through a different connection instead. This is an event-driven approach to connectivity resilience.

More event-driven computing on AWS

In addition to SNS, event-driven computing is also addressed by Amazon CloudWatch Events, which delivers a near real-time stream of system events that describe changes in AWS resources. With CloudWatch Events, you can route each event type to one or more targets, including:

Many AWS services publish events to CloudWatch. As an example, you can get CloudWatch Events to capture events on your ETL (Extract, Transform, Load) jobs running on AWS Glue and push failed ones to an SQS queue, so that you can retry them later.

Conclusion

Amazon SNS is a pub/sub messaging service that can be used as an event-driven computing hub to AWS customers worldwide. By capturing events natively triggered by AWS services, such as EC2, S3 and RDS, you can automate and optimize all kinds of workflows, namely scaling, testing, encoding, profiling, broadcasting, discovery, failover, and much more. Business use cases presented in this post ranged from recruiting websites, to scientific research, geographic systems, social networks, retail websites, and news portals.

Start now by visiting Amazon SNS in the AWS Management Console, or by trying the AWS 10-Minute Tutorial, Send Fan-out Event Notifications with Amazon SNS and Amazon SQS.

 

Capturing Custom, High-Resolution Metrics from Containers Using AWS Step Functions and AWS Lambda

Post Syndicated from Nathan Taber original https://aws.amazon.com/blogs/compute/capturing-custom-high-resolution-metrics-from-containers-using-aws-step-functions-and-aws-lambda/

Contributed by Trevor Sullivan, AWS Solutions Architect

When you deploy containers with Amazon ECS, are you gathering all of the key metrics so that you can correctly monitor the overall health of your ECS cluster?

By default, ECS writes metrics to Amazon CloudWatch in 5-minute increments. For complex or large services, this may not be sufficient to make scaling decisions quickly. You may want to respond immediately to changes in workload or to identify application performance problems. Last July, CloudWatch announced support for high-resolution metrics, up to a per-second basis.

These high-resolution metrics can be used to give you a clearer picture of the load and performance for your applications, containers, clusters, and hosts. In this post, I discuss how you can use AWS Step Functions, along with AWS Lambda, to cost effectively record high-resolution metrics into CloudWatch. You implement this solution using a serverless architecture, which keeps your costs low and makes it easier to troubleshoot the solution.

To show how this works, you retrieve some useful metric data from an ECS cluster running in the same AWS account and region (Oregon, us-west-2) as the Step Functions state machine and Lambda function. However, you can use this architecture to retrieve any custom application metrics from any resource in any AWS account and region.

Why Step Functions?

Step Functions enables you to orchestrate multi-step tasks in the AWS Cloud that run for any period of time, up to a year. Effectively, you’re building a blueprint for an end-to-end process. After it’s built, you can execute the process as many times as you want.

For this architecture, you gather metrics from an ECS cluster, every five seconds, and then write the metric data to CloudWatch. After your ECS cluster metrics are stored in CloudWatch, you can create CloudWatch alarms to notify you. An alarm can also trigger an automated remediation activity such as scaling ECS services, when a metric exceeds a threshold defined by you.

When you build a Step Functions state machine, you define the different states inside it as JSON objects. The bulk of the work in Step Functions is handled by the common task state, which invokes Lambda functions or Step Functions activities. There is also a built-in library of other useful states that allow you to control the execution flow of your program.

One of the most useful state types in Step Functions is the parallel state. Each parallel state in your state machine can have one or more branches, each of which is executed in parallel. Another useful state type is the wait state, which waits for a period of time before moving to the next state.

In this walkthrough, you combine these three states (parallel, wait, and task) to create a state machine that triggers a Lambda function, which then gathers metrics from your ECS cluster.

Step Functions pricing

This state machine is executed every minute, resulting in 60 executions per hour, and 1,440 executions per day. Step Functions is billed per state transition, including the Start and End state transitions, and giving you approximately 37,440 state transitions per day. To reach this number, I’m using this estimated math:

26 state transitions per-execution x 60 minutes x 24 hours

Based on current pricing, at $0.000025 per state transition, the daily cost of this metric gathering state machine would be $0.936.

Step Functions offers an indefinite 4,000 free state transitions every month. This benefit is available to all customers, not just customers who are still under the 12-month AWS Free Tier. For more information and cost example scenarios, see Step Functions pricing.

Why Lambda?

The goal is to capture metrics from an ECS cluster, and write the metric data to CloudWatch. This is a straightforward, short-running process that makes Lambda the perfect place to run your code. Lambda is one of the key services that makes up “Serverless” application architectures. It enables you to consume compute capacity only when your code is actually executing.

The process of gathering metric data from ECS and writing it to CloudWatch takes a short period of time. In fact, my average Lambda function execution time, while developing this post, is only about 250 milliseconds on average. For every five-second interval that occurs, I’m only using 1/20th of the compute time that I’d otherwise be paying for.

Lambda pricing

For billing purposes, Lambda execution time is rounded up to the nearest 100-ms interval. In general, based on the metrics that I observed during development, a 250-ms runtime would be billed at 300 ms. Here, I calculate the cost of this Lambda function executing on a daily basis.

Assuming 31 days in each month, there would be 535,680 five-second intervals (31 days x 24 hours x 60 minutes x 12 five-second intervals = 535,680). The Lambda function is invoked every five-second interval, by the Step Functions state machine, and runs for a 300-ms period. At current Lambda pricing, for a 128-MB function, you would be paying approximately the following:

Total compute

Total executions = 535,680
Total compute = total executions x (3 x $0.000000208 per 100 ms) = $0.334 per day

Total requests

Total requests = (535,680 / 1000000) * $0.20 per million requests = $0.11 per day

Total Lambda Cost

$0.11 requests + $0.334 compute time = $0.444 per day

Similar to Step Functions, Lambda offers an indefinite free tier. For more information, see Lambda Pricing.

Walkthrough

In the following sections, I step through the process of configuring the solution just discussed. If you follow along, at a high level, you will:

  • Configure an IAM role and policy
  • Create a Step Functions state machine to control metric gathering execution
  • Create a metric-gathering Lambda function
  • Configure a CloudWatch Events rule to trigger the state machine
  • Validate the solution

Prerequisites

You should already have an AWS account with a running ECS cluster. If you don’t have one running, you can easily deploy a Docker container on an ECS cluster using the AWS Management Console. In the example produced for this post, I use an ECS cluster running Windows Server (currently in beta), but either a Linux or Windows Server cluster works.

Create an IAM role and policy

First, create an IAM role and policy that enables Step Functions, Lambda, and CloudWatch to communicate with each other.

  • The CloudWatch Events rule needs permissions to trigger the Step Functions state machine.
  • The Step Functions state machine needs permissions to trigger the Lambda function.
  • The Lambda function needs permissions to query ECS and then write to CloudWatch Logs and metrics.

When you create the state machine, Lambda function, and CloudWatch Events rule, you assign this role to each of those resources. Upon execution, each of these resources assumes the specified role and executes using the role’s permissions.

  1. Open the IAM console.
  2. Choose Roles, create New Role.
  3. For Role Name, enter WriteMetricFromStepFunction.
  4. Choose Save.

Create the IAM role trust relationship
The trust relationship (also known as the assume role policy document) for your IAM role looks like the following JSON document. As you can see from the document, your IAM role needs to trust the Lambda, CloudWatch Events, and Step Functions services. By configuring your role to trust these services, they can assume this role and inherit the role permissions.

  1. Open the IAM console.
  2. Choose Roles and select the IAM role previously created.
  3. Choose Trust RelationshipsEdit Trust Relationships.
  4. Enter the following trust policy text and choose Save.
{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Principal": {
        "Service": "lambda.amazonaws.com"
      },
      "Action": "sts:AssumeRole"
    },
    {
      "Effect": "Allow",
      "Principal": {
        "Service": "events.amazonaws.com"
      },
      "Action": "sts:AssumeRole"
    },
    {
      "Effect": "Allow",
      "Principal": {
        "Service": "states.us-west-2.amazonaws.com"
      },
      "Action": "sts:AssumeRole"
    }
  ]
}

Create an IAM policy

After you’ve finished configuring your role’s trust relationship, grant the role access to the other AWS resources that make up the solution.

The IAM policy is what gives your IAM role permissions to access various resources. You must whitelist explicitly the specific resources to which your role has access, because the default IAM behavior is to deny access to any AWS resources.

I’ve tried to keep this policy document as generic as possible, without allowing permissions to be too open. If the name of your ECS cluster is different than the one in the example policy below, make sure that you update the policy document before attaching it to your IAM role. You can attach this policy as an inline policy, instead of creating the policy separately first. However, either approach is valid.

  1. Open the IAM console.
  2. Select the IAM role, and choose Permissions.
  3. Choose Add in-line policy.
  4. Choose Custom Policy and then enter the following policy. The inline policy name does not matter.
{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Allow",
            "Action": [ "logs:*" ],
            "Resource": "*"
        },
        {
            "Effect": "Allow",
            "Action": [ "cloudwatch:PutMetricData" ],
            "Resource": "*"
        },
        {
            "Effect": "Allow",
            "Action": [ "states:StartExecution" ],
            "Resource": [
                "arn:aws:states:*:*:stateMachine:WriteMetricFromStepFunction"
            ]
        },
        {
            "Effect": "Allow",
            "Action": [ "lambda:InvokeFunction" ],
            "Resource": "arn:aws:lambda:*:*:function:WriteMetricFromStepFunction"
        },
        {
            "Effect": "Allow",
            "Action": [ "ecs:Describe*" ],
            "Resource": "arn:aws:ecs:*:*:cluster/ECSEsgaroth"
        }
    ]
}

Create a Step Functions state machine

In this section, you create a Step Functions state machine that invokes the metric-gathering Lambda function every five (5) seconds, for a one-minute period. If you divide a minute (60) seconds into equal parts of five-second intervals, you get 12. Based on this math, you create 12 branches, in a single parallel state, in the state machine. Each branch triggers the metric-gathering Lambda function at a different five-second marker, throughout the one-minute period. After all of the parallel branches finish executing, the Step Functions execution completes and another begins.

Follow these steps to create your Step Functions state machine:

  1. Open the Step Functions console.
  2. Choose DashboardCreate State Machine.
  3. For State Machine Name, enter WriteMetricFromStepFunction.
  4. Enter the state machine code below into the editor. Make sure that you insert your own AWS account ID for every instance of “676655494xxx”
  5. Choose Create State Machine.
  6. Select the WriteMetricFromStepFunction IAM role that you previously created.
{
    "Comment": "Writes ECS metrics to CloudWatch every five seconds, for a one-minute period.",
    "StartAt": "ParallelMetric",
    "States": {
      "ParallelMetric": {
        "Type": "Parallel",
        "Branches": [
          {
            "StartAt": "WriteMetricLambda",
            "States": {
             	"WriteMetricLambda": {
                  "Type": "Task",
				  "Resource": "arn:aws:lambda:us-west-2:676655494xxx:function:WriteMetricFromStepFunction",
                  "End": true
                } 
            }
          },
    	  {
            "StartAt": "WaitFive",
            "States": {
            	"WaitFive": {
            		"Type": "Wait",
            		"Seconds": 5,
            		"Next": "WriteMetricLambdaFive"
          		},
             	"WriteMetricLambdaFive": {
                  "Type": "Task",
				  "Resource": "arn:aws:lambda:us-west-2:676655494xxx:function:WriteMetricFromStepFunction",
                  "End": true
                } 
            }
          },
    	  {
            "StartAt": "WaitTen",
            "States": {
            	"WaitTen": {
            		"Type": "Wait",
            		"Seconds": 10,
            		"Next": "WriteMetricLambda10"
          		},
             	"WriteMetricLambda10": {
                  "Type": "Task",
                  "Resource": "arn:aws:lambda:us-west-2:676655494xxx:function:WriteMetricFromStepFunction",
                  "End": true
                } 
            }
          },
    	  {
            "StartAt": "WaitFifteen",
            "States": {
            	"WaitFifteen": {
            		"Type": "Wait",
            		"Seconds": 15,
            		"Next": "WriteMetricLambda15"
          		},
             	"WriteMetricLambda15": {
                  "Type": "Task",
                  "Resource": "arn:aws:lambda:us-west-2:676655494xxx:function:WriteMetricFromStepFunction",
                  "End": true
                } 
            }
          },
          {
            "StartAt": "Wait20",
            "States": {
            	"Wait20": {
            		"Type": "Wait",
            		"Seconds": 20,
            		"Next": "WriteMetricLambda20"
          		},
             	"WriteMetricLambda20": {
                  "Type": "Task",
                  "Resource": "arn:aws:lambda:us-west-2:676655494xxx:function:WriteMetricFromStepFunction",
                  "End": true
                } 
            }
          },
          {
            "StartAt": "Wait25",
            "States": {
            	"Wait25": {
            		"Type": "Wait",
            		"Seconds": 25,
            		"Next": "WriteMetricLambda25"
          		},
             	"WriteMetricLambda25": {
                  "Type": "Task",
                  "Resource": "arn:aws:lambda:us-west-2:676655494xxx:function:WriteMetricFromStepFunction",
                  "End": true
                } 
            }
          },
          {
            "StartAt": "Wait30",
            "States": {
            	"Wait30": {
            		"Type": "Wait",
            		"Seconds": 30,
            		"Next": "WriteMetricLambda30"
          		},
             	"WriteMetricLambda30": {
                  "Type": "Task",
                  "Resource": "arn:aws:lambda:us-west-2:676655494xxx:function:WriteMetricFromStepFunction",
                  "End": true
                } 
            }
          },
          {
            "StartAt": "Wait35",
            "States": {
            	"Wait35": {
            		"Type": "Wait",
            		"Seconds": 35,
            		"Next": "WriteMetricLambda35"
          		},
             	"WriteMetricLambda35": {
                  "Type": "Task",
                  "Resource": "arn:aws:lambda:us-west-2:676655494xxx:function:WriteMetricFromStepFunction",
                  "End": true
                } 
            }
          },
          {
            "StartAt": "Wait40",
            "States": {
            	"Wait40": {
            		"Type": "Wait",
            		"Seconds": 40,
            		"Next": "WriteMetricLambda40"
          		},
             	"WriteMetricLambda40": {
                  "Type": "Task",
                  "Resource": "arn:aws:lambda:us-west-2:676655494xxx:function:WriteMetricFromStepFunction",
                  "End": true
                } 
            }
          },
          {
            "StartAt": "Wait45",
            "States": {
            	"Wait45": {
            		"Type": "Wait",
            		"Seconds": 45,
            		"Next": "WriteMetricLambda45"
          		},
             	"WriteMetricLambda45": {
                  "Type": "Task",
                  "Resource": "arn:aws:lambda:us-west-2:676655494xxx:function:WriteMetricFromStepFunction",
                  "End": true
                } 
            }
          },
          {
            "StartAt": "Wait50",
            "States": {
            	"Wait50": {
            		"Type": "Wait",
            		"Seconds": 50,
            		"Next": "WriteMetricLambda50"
          		},
             	"WriteMetricLambda50": {
                  "Type": "Task",
                  "Resource": "arn:aws:lambda:us-west-2:676655494xxx:function:WriteMetricFromStepFunction",
                  "End": true
                } 
            }
          },
          {
            "StartAt": "Wait55",
            "States": {
            	"Wait55": {
            		"Type": "Wait",
            		"Seconds": 55,
            		"Next": "WriteMetricLambda55"
          		},
             	"WriteMetricLambda55": {
                  "Type": "Task",
                  "Resource": "arn:aws:lambda:us-west-2:676655494xxx:function:WriteMetricFromStepFunction",
                  "End": true
                } 
            }
          }
        ],
        "End": true
      }
  }
}

Now you’ve got a shiny new Step Functions state machine! However, you might ask yourself, “After the state machine has been created, how does it get executed?” Before I answer that question, create the Lambda function that writes the custom metric, and then you get the end-to-end process moving.

Create a Lambda function

The meaty part of the solution is a Lambda function, written to consume the Python 3.6 runtime, that retrieves metric values from ECS, and then writes them to CloudWatch. This Lambda function is what the Step Functions state machine is triggering every five seconds, via the Task states. Key points to remember:

The Lambda function needs permission to:

  • Write CloudWatch metrics (PutMetricData API).
  • Retrieve metrics from ECS clusters (DescribeCluster API).
  • Write StdOut to CloudWatch Logs.

Boto3, the AWS SDK for Python, is included in the Lambda execution environment for Python 2.x and 3.x.

Because Lambda includes the AWS SDK, you don’t have to worry about packaging it up and uploading it to Lambda. You can focus on writing code and automatically take a dependency on boto3.

As for permissions, you’ve already created the IAM role and attached a policy to it that enables your Lambda function to access the necessary API actions. When you create your Lambda function, make sure that you select the correct IAM role, to ensure it is invoked with the correct permissions.

The following Lambda function code is generic. So how does the Lambda function know which ECS cluster to gather metrics for? Your Step Functions state machine automatically passes in its state to the Lambda function. When you create your CloudWatch Events rule, you specify a simple JSON object that passes the desired ECS cluster name into your Step Functions state machine, which then passes it to the Lambda function.

Use the following property values as you create your Lambda function:

Function Name: WriteMetricFromStepFunction
Description: This Lambda function retrieves metric values from an ECS cluster and writes them to Amazon CloudWatch.
Runtime: Python3.6
Memory: 128 MB
IAM Role: WriteMetricFromStepFunction

import boto3

def handler(event, context):
    cw = boto3.client('cloudwatch')
    ecs = boto3.client('ecs')
    print('Got boto3 client objects')
    
    Dimension = {
        'Name': 'ClusterName',
        'Value': event['ECSClusterName']
    }

    cluster = get_ecs_cluster(ecs, Dimension['Value'])
    
    cw_args = {
       'Namespace': 'ECS',
       'MetricData': [
           {
               'MetricName': 'RunningTask',
               'Dimensions': [ Dimension ],
               'Value': cluster['runningTasksCount'],
               'Unit': 'Count',
               'StorageResolution': 1
           },
           {
               'MetricName': 'PendingTask',
               'Dimensions': [ Dimension ],
               'Value': cluster['pendingTasksCount'],
               'Unit': 'Count',
               'StorageResolution': 1
           },
           {
               'MetricName': 'ActiveServices',
               'Dimensions': [ Dimension ],
               'Value': cluster['activeServicesCount'],
               'Unit': 'Count',
               'StorageResolution': 1
           },
           {
               'MetricName': 'RegisteredContainerInstances',
               'Dimensions': [ Dimension ],
               'Value': cluster['registeredContainerInstancesCount'],
               'Unit': 'Count',
               'StorageResolution': 1
           }
        ]
    }
    cw.put_metric_data(**cw_args)
    print('Finished writing metric data')
    
def get_ecs_cluster(client, cluster_name):
    cluster = client.describe_clusters(clusters = [ cluster_name ])
    print('Retrieved cluster details from ECS')
    return cluster['clusters'][0]

Create the CloudWatch Events rule

Now you’ve created an IAM role and policy, Step Functions state machine, and Lambda function. How do these components actually start communicating with each other? The final step in this process is to set up a CloudWatch Events rule that triggers your metric-gathering Step Functions state machine every minute. You have two choices for your CloudWatch Events rule expression: rate or cron. In this example, use the cron expression.

A couple key learning points from creating the CloudWatch Events rule:

  • You can specify one or more targets, of different types (for example, Lambda function, Step Functions state machine, SNS topic, and so on).
  • You’re required to specify an IAM role with permissions to trigger your target.
    NOTE: This applies only to certain types of targets, including Step Functions state machines.
  • Each target that supports IAM roles can be triggered using a different IAM role, in the same CloudWatch Events rule.
  • Optional: You can provide custom JSON that is passed to your target Step Functions state machine as input.

Follow these steps to create the CloudWatch Events rule:

  1. Open the CloudWatch console.
  2. Choose Events, RulesCreate Rule.
  3. Select Schedule, Cron Expression, and then enter the following rule:
    0/1 * * * ? *
  4. Choose Add Target, Step Functions State MachineWriteMetricFromStepFunction.
  5. For Configure Input, select Constant (JSON Text).
  6. Enter the following JSON input, which is passed to Step Functions, while changing the cluster name accordingly:
    { "ECSClusterName": "ECSEsgaroth" }
  7. Choose Use Existing Role, WriteMetricFromStepFunction (the IAM role that you previously created).

After you’ve completed with these steps, your screen should look similar to this:

Validate the solution

Now that you have finished implementing the solution to gather high-resolution metrics from ECS, validate that it’s working properly.

  1. Open the CloudWatch console.
  2. Choose Metrics.
  3. Choose custom and select the ECS namespace.
  4. Choose the ClusterName metric dimension.

You should see your metrics listed below.

Troubleshoot configuration issues

If you aren’t receiving the expected ECS cluster metrics in CloudWatch, check for the following common configuration issues. Review the earlier procedures to make sure that the resources were properly configured.

  • The IAM role’s trust relationship is incorrectly configured.
    Make sure that the IAM role trusts Lambda, CloudWatch Events, and Step Functions in the correct region.
  • The IAM role does not have the correct policies attached to it.
    Make sure that you have copied the IAM policy correctly as an inline policy on the IAM role.
  • The CloudWatch Events rule is not triggering new Step Functions executions.
    Make sure that the target configuration on the rule has the correct Step Functions state machine and IAM role selected.
  • The Step Functions state machine is being executed, but failing part way through.
    Examine the detailed error message on the failed state within the failed Step Functions execution. It’s possible that the
  • IAM role does not have permissions to trigger the target Lambda function, that the target Lambda function may not exist, or that the Lambda function failed to complete successfully due to invalid permissions.
    Although the above list covers several different potential configuration issues, it is not comprehensive. Make sure that you understand how each service is connected to each other, how permissions are granted through IAM policies, and how IAM trust relationships work.

Conclusion

In this post, you implemented a Serverless solution to gather and record high-resolution application metrics from containers running on Amazon ECS into CloudWatch. The solution consists of a Step Functions state machine, Lambda function, CloudWatch Events rule, and an IAM role and policy. The data that you gather from this solution helps you rapidly identify issues with an ECS cluster.

To gather high-resolution metrics from any service, modify your Lambda function to gather the correct metrics from your target. If you prefer not to use Python, you can implement a Lambda function using one of the other supported runtimes, including Node.js, Java, or .NET Core. However, this post should give you the fundamental basics about capturing high-resolution metrics in CloudWatch.

If you found this post useful, or have questions, please comment below.

Updated AWS SOC Reports Are Now Available with 19 Additional Services in Scope

Post Syndicated from Chad Woolf original https://aws.amazon.com/blogs/security/updated-aws-soc-reports-are-now-available-with-19-additional-services-in-scope/

AICPA SOC logo

Newly updated reports are available for AWS System and Organization Control Report 1 (SOC 1), formerly called AWS Service Organization Control Report 1, and AWS SOC 2: Security, Availability, & Confidentiality Report. You can download both reports for free and on demand in the AWS Management Console through AWS Artifact. The updated AWS SOC 3: Security, Availability, & Confidentiality Report also was just released. All three reports cover April 1, 2017, through September 30, 2017.

With the addition of the following 19 services, AWS now supports 51 SOC-compliant AWS services and is committed to increasing the number:

  • Amazon API Gateway
  • Amazon Cloud Directory
  • Amazon CloudFront
  • Amazon Cognito
  • Amazon Connect
  • AWS Directory Service for Microsoft Active Directory
  • Amazon EC2 Container Registry
  • Amazon EC2 Container Service
  • Amazon EC2 Systems Manager
  • Amazon Inspector
  • AWS IoT Platform
  • Amazon Kinesis Streams
  • AWS Lambda
  • AWS [email protected]
  • AWS Managed Services
  • Amazon S3 Transfer Acceleration
  • AWS Shield
  • AWS Step Functions
  • AWS WAF

With this release, we also are introducing a separate spreadsheet, eliminating the need to extract the information from multiple PDFs.

If you are not yet an AWS customer, contact AWS Compliance to access the SOC Reports.

– Chad

Using AWS Step Functions State Machines to Handle Workflow-Driven AWS CodePipeline Actions

Post Syndicated from Marcilio Mendonca original https://aws.amazon.com/blogs/devops/using-aws-step-functions-state-machines-to-handle-workflow-driven-aws-codepipeline-actions/

AWS CodePipeline is a continuous integration and continuous delivery service for fast and reliable application and infrastructure updates. It offers powerful integration with other AWS services, such as AWS CodeBuildAWS CodeDeployAWS CodeCommit, AWS CloudFormation and with third-party tools such as Jenkins and GitHub. These services make it possible for AWS customers to successfully automate various tasks, including infrastructure provisioning, blue/green deployments, serverless deployments, AMI baking, database provisioning, and release management.

Developers have been able to use CodePipeline to build sophisticated automation pipelines that often require a single CodePipeline action to perform multiple tasks, fork into different execution paths, and deal with asynchronous behavior. For example, to deploy a Lambda function, a CodePipeline action might first inspect the changes pushed to the code repository. If only the Lambda code has changed, the action can simply update the Lambda code package, create a new version, and point the Lambda alias to the new version. If the changes also affect infrastructure resources managed by AWS CloudFormation, the pipeline action might have to create a stack or update an existing one through the use of a change set. In addition, if an update is required, the pipeline action might enforce a safety policy to infrastructure resources that prevents the deletion and replacement of resources. You can do this by creating a change set and having the pipeline action inspect its changes before updating the stack. Change sets that do not conform to the policy are deleted.

This use case is a good illustration of workflow-driven pipeline actions. These are actions that run multiple tasks, deal with async behavior and loops, need to maintain and propagate state, and fork into different execution paths. Implementing workflow-driven actions directly in CodePipeline can lead to complex pipelines that are hard for developers to understand and maintain. Ideally, a pipeline action should perform a single task and delegate the complexity of dealing with workflow-driven behavior associated with that task to a state machine engine. This would make it possible for developers to build simpler, more intuitive pipelines and allow them to use state machine execution logs to visualize and troubleshoot their pipeline actions.

In this blog post, we discuss how AWS Step Functions state machines can be used to handle workflow-driven actions. We show how a CodePipeline action can trigger a Step Functions state machine and how the pipeline and the state machine are kept decoupled through a Lambda function. The advantages of using state machines include:

  • Simplified logic (complex tasks are broken into multiple smaller tasks).
  • Ease of handling asynchronous behavior (through state machine wait states).
  • Built-in support for choices and processing different execution paths (through state machine choices).
  • Built-in visualization and logging of the state machine execution.

The source code for the sample pipeline, pipeline actions, and state machine used in this post is available at https://github.com/awslabs/aws-codepipeline-stepfunctions.

Overview

This figure shows the components in the CodePipeline-Step Functions integration that will be described in this post. The pipeline contains two stages: a Source stage represented by a CodeCommit Git repository and a Prod stage with a single Deploy action that represents the workflow-driven action.

This action invokes a Lambda function (1) called the State Machine Trigger Lambda, which, in turn, triggers a Step Function state machine to process the request (2). The Lambda function sends a continuation token back to the pipeline (3) to continue its execution later and terminates. Seconds later, the pipeline invokes the Lambda function again (4), passing the continuation token received. The Lambda function checks the execution state of the state machine (5,6) and communicates the status to the pipeline. The process is repeated until the state machine execution is complete. Then the Lambda function notifies the pipeline that the corresponding pipeline action is complete (7). If the state machine has failed, the Lambda function will then fail the pipeline action and stop its execution (7). While running, the state machine triggers various Lambda functions to perform different tasks. The state machine and the pipeline are fully decoupled. Their interaction is handled by the Lambda function.

The Deploy State Machine

The sample state machine used in this post is a simplified version of the use case, with emphasis on infrastructure deployment. The state machine will follow distinct execution paths and thus have different outcomes, depending on:

  • The current state of the AWS CloudFormation stack.
  • The nature of the code changes made to the AWS CloudFormation template and pushed into the pipeline.

If the stack does not exist, it will be created. If the stack exists, a change set will be created and its resources inspected by the state machine. The inspection consists of parsing the change set results and detecting whether any resources will be deleted or replaced. If no resources are being deleted or replaced, the change set is allowed to be executed and the state machine completes successfully. Otherwise, the change set is deleted and the state machine completes execution with a failure as the terminal state.

Let’s dive into each of these execution paths.

Path 1: Create a Stack and Succeed Deployment

The Deploy state machine is shown here. It is triggered by the Lambda function using the following input parameters stored in an S3 bucket.

Create New Stack Execution Path

{
    "environmentName": "prod",
    "stackName": "sample-lambda-app",
    "templatePath": "infra/Lambda-template.yaml",
    "revisionS3Bucket": "codepipeline-us-east-1-418586629775",
    "revisionS3Key": "StepFunctionsDrivenD/CodeCommit/sjcmExZ"
}

Note that some values used here are for the use case example only. Account-specific parameters like revisionS3Bucket and revisionS3Key will be different when you deploy this use case in your account.

These input parameters are used by various states in the state machine and passed to the corresponding Lambda functions to perform different tasks. For example, stackName is used to create a stack, check the status of stack creation, and create a change set. The environmentName represents the environment (for example, dev, test, prod) to which the code is being deployed. It is used to prefix the name of stacks and change sets.

With the exception of built-in states such as wait and choice, each state in the state machine invokes a specific Lambda function.  The results received from the Lambda invocations are appended to the state machine’s original input. When the state machine finishes its execution, several parameters will have been added to its original input.

The first stage in the state machine is “Check Stack Existence”. It checks whether a stack with the input name specified in the stackName input parameter already exists. The output of the state adds a Boolean value called doesStackExist to the original state machine input as follows:

{
  "doesStackExist": true,
  "environmentName": "prod",
  "stackName": "sample-lambda-app",
  "templatePath": "infra/lambda-template.yaml",
  "revisionS3Bucket": "codepipeline-us-east-1-418586629775",
  "revisionS3Key": "StepFunctionsDrivenD/CodeCommit/sjcmExZ",
}

The following stage, “Does Stack Exist?”, is represented by Step Functions built-in choice state. It checks the value of doesStackExist to determine whether a new stack needs to be created (doesStackExist=true) or a change set needs to be created and inspected (doesStackExist=false).

If the stack does not exist, the states illustrated in green in the preceding figure are executed. This execution path creates the stack, waits until the stack is created, checks the status of the stack’s creation, and marks the deployment successful after the stack has been created. Except for “Stack Created?” and “Wait Stack Creation,” each of these stages invokes a Lambda function. “Stack Created?” and “Wait Stack Creation” are implemented by using the built-in choice state (to decide which path to follow) and the wait state (to wait a few seconds before proceeding), respectively. Each stage adds the results of their Lambda function executions to the initial input of the state machine, allowing future stages to process them.

Path 2: Safely Update a Stack and Mark Deployment as Successful

Safely Update a Stack and Mark Deployment as Successful Execution Path

If the stack indicated by the stackName parameter already exists, a different path is executed. (See the green states in the figure.) This path will create a change set and use wait and choice states to wait until the change set is created. Afterwards, a stage in the execution path will inspect  the resources affected before the change set is executed.

The inspection procedure represented by the “Inspect Change Set Changes” stage consists of parsing the resources affected by the change set and checking whether any of the existing resources are being deleted or replaced. The following is an excerpt of the algorithm, where changeSetChanges.Changes is the object representing the change set changes:

...
var RESOURCES_BEING_DELETED_OR_REPLACED = "RESOURCES-BEING-DELETED-OR-REPLACED";
var CAN_SAFELY_UPDATE_EXISTING_STACK = "CAN-SAFELY-UPDATE-EXISTING-STACK";
for (var i = 0; i < changeSetChanges.Changes.length; i++) {
    var change = changeSetChanges.Changes[i];
    if (change.Type == "Resource") {
        if (change.ResourceChange.Action == "Delete") {
            return RESOURCES_BEING_DELETED_OR_REPLACED;
        }
        if (change.ResourceChange.Action == "Modify") {
            if (change.ResourceChange.Replacement == "True") {
                return RESOURCES_BEING_DELETED_OR_REPLACED;
            }
        }
    }
}
return CAN_SAFELY_UPDATE_EXISTING_STACK;

The algorithm returns different values to indicate whether the change set can be safely executed (CAN_SAFELY_UPDATE_EXISTING_STACK or RESOURCES_BEING_DELETED_OR_REPLACED). This value is used later by the state machine to decide whether to execute the change set and update the stack or interrupt the deployment.

The output of the “Inspect Change Set” stage is shown here.

{
  "environmentName": "prod",
  "stackName": "sample-lambda-app",
  "templatePath": "infra/lambda-template.yaml",
  "revisionS3Bucket": "codepipeline-us-east-1-418586629775",
  "revisionS3Key": "StepFunctionsDrivenD/CodeCommit/sjcmExZ",
  "doesStackExist": true,
  "changeSetName": "prod-sample-lambda-app-change-set-545",
  "changeSetCreationStatus": "complete",
  "changeSetAction": "CAN-SAFELY-UPDATE-EXISTING-STACK"
}

At this point, these parameters have been added to the state machine’s original input:

  • changeSetName, which is added by the “Create Change Set” state.
  • changeSetCreationStatus, which is added by the “Get Change Set Creation Status” state.
  • changeSetAction, which is added by the “Inspect Change Set Changes” state.

The “Safe to Update Infra?” step is a choice state (its JSON spec follows) that simply checks the value of the changeSetAction parameter. If the value is equal to “CAN-SAFELY-UPDATE-EXISTING-STACK“, meaning that no resources will be deleted or replaced, the step will execute the change set by proceeding to the “Execute Change Set” state. The deployment is successful (the state machine completes its execution successfully).

"Safe to Update Infra?": {
      "Type": "Choice",
      "Choices": [
        {
          "Variable": "$.taskParams.changeSetAction",
          "StringEquals": "CAN-SAFELY-UPDATE-EXISTING-STACK",
          "Next": "Execute Change Set"
        }
      ],
      "Default": "Deployment Failed"
 }

Path 3: Reject Stack Update and Fail Deployment

Reject Stack Update and Fail Deployment Execution Path

If the changeSetAction parameter is different from “CAN-SAFELY-UPDATE-EXISTING-STACK“, the state machine will interrupt the deployment by deleting the change set and proceeding to the “Deployment Fail” step, which is a built-in Fail state. (Its JSON spec follows.) This state causes the state machine to stop in a failed state and serves to indicate to the Lambda function that the pipeline deployment should be interrupted in a fail state as well.

 "Deployment Failed": {
      "Type": "Fail",
      "Cause": "Deployment Failed",
      "Error": "Deployment Failed"
    }

In all three scenarios, there’s a state machine’s visual representation available in the AWS Step Functions console that makes it very easy for developers to identify what tasks have been executed or why a deployment has failed. Developers can also inspect the inputs and outputs of each state and look at the state machine Lambda function’s logs for details. Meanwhile, the corresponding CodePipeline action remains very simple and intuitive for developers who only need to know whether the deployment was successful or failed.

The State Machine Trigger Lambda Function

The Trigger Lambda function is invoked directly by the Deploy action in CodePipeline. The CodePipeline action must pass a JSON structure to the trigger function through the UserParameters attribute, as follows:

{
  "s3Bucket": "codepipeline-StepFunctions-sample",
  "stateMachineFile": "state_machine_input.json"
}

The s3Bucket parameter specifies the S3 bucket location for the state machine input parameters file. The stateMachineFile parameter specifies the file holding the input parameters. By being able to specify different input parameters to the state machine, we make the Trigger Lambda function and the state machine reusable across environments. For example, the same state machine could be called from a test and prod pipeline action by specifying a different S3 bucket or state machine input file for each environment.

The Trigger Lambda function performs two main tasks: triggering the state machine and checking the execution state of the state machine. Its core logic is shown here:

exports.index = function (event, context, callback) {
    try {
        console.log("Event: " + JSON.stringify(event));
        console.log("Context: " + JSON.stringify(context));
        console.log("Environment Variables: " + JSON.stringify(process.env));
        if (Util.isContinuingPipelineTask(event)) {
            monitorStateMachineExecution(event, context, callback);
        }
        else {
            triggerStateMachine(event, context, callback);
        }
    }
    catch (err) {
        failure(Util.jobId(event), callback, context.invokeid, err.message);
    }
}

Util.isContinuingPipelineTask(event) is a utility function that checks if the Trigger Lambda function is being called for the first time (that is, no continuation token is passed by CodePipeline) or as a continuation of a previous call. In its first execution, the Lambda function will trigger the state machine and send a continuation token to CodePipeline that contains the state machine execution ARN. The state machine ARN is exposed to the Lambda function through a Lambda environment variable called stateMachineArn. Here is the code that triggers the state machine:

function triggerStateMachine(event, context, callback) {
    var stateMachineArn = process.env.stateMachineArn;
    var s3Bucket = Util.actionUserParameter(event, "s3Bucket");
    var stateMachineFile = Util.actionUserParameter(event, "stateMachineFile");
    getStateMachineInputData(s3Bucket, stateMachineFile)
        .then(function (data) {
            var initialParameters = data.Body.toString();
            var stateMachineInputJSON = createStateMachineInitialInput(initialParameters, event);
            console.log("State machine input JSON: " + JSON.stringify(stateMachineInputJSON));
            return stateMachineInputJSON;
        })
        .then(function (stateMachineInputJSON) {
            return triggerStateMachineExecution(stateMachineArn, stateMachineInputJSON);
        })
        .then(function (triggerStateMachineOutput) {
            var continuationToken = { "stateMachineExecutionArn": triggerStateMachineOutput.executionArn };
            var message = "State machine has been triggered: " + JSON.stringify(triggerStateMachineOutput) + ", continuationToken: " + JSON.stringify(continuationToken);
            return continueExecution(Util.jobId(event), continuationToken, callback, message);
        })
        .catch(function (err) {
            console.log("Error triggering state machine: " + stateMachineArn + ", Error: " + err.message);
            failure(Util.jobId(event), callback, context.invokeid, err.message);
        })
}

The Trigger Lambda function fetches the state machine input parameters from an S3 file, triggers the execution of the state machine using the input parameters and the stateMachineArn environment variable, and signals to CodePipeline that the execution should continue later by passing a continuation token that contains the state machine execution ARN. In case any of these operations fail and an exception is thrown, the Trigger Lambda function will fail the pipeline immediately by signaling a pipeline failure through the putJobFailureResult CodePipeline API.

If the Lambda function is continuing a previous execution, it will extract the state machine execution ARN from the continuation token and check the status of the state machine, as shown here.

function monitorStateMachineExecution(event, context, callback) {
    var stateMachineArn = process.env.stateMachineArn;
    var continuationToken = JSON.parse(Util.continuationToken(event));
    var stateMachineExecutionArn = continuationToken.stateMachineExecutionArn;
    getStateMachineExecutionStatus(stateMachineExecutionArn)
        .then(function (response) {
            if (response.status === "RUNNING") {
                var message = "Execution: " + stateMachineExecutionArn + " of state machine: " + stateMachineArn + " is still " + response.status;
                return continueExecution(Util.jobId(event), continuationToken, callback, message);
            }
            if (response.status === "SUCCEEDED") {
                var message = "Execution: " + stateMachineExecutionArn + " of state machine: " + stateMachineArn + " has: " + response.status;
                return success(Util.jobId(event), callback, message);
            }
            // FAILED, TIMED_OUT, ABORTED
            var message = "Execution: " + stateMachineExecutionArn + " of state machine: " + stateMachineArn + " has: " + response.status;
            return failure(Util.jobId(event), callback, context.invokeid, message);
        })
        .catch(function (err) {
            var message = "Error monitoring execution: " + stateMachineExecutionArn + " of state machine: " + stateMachineArn + ", Error: " + err.message;
            failure(Util.jobId(event), callback, context.invokeid, message);
        });
}

If the state machine is in the RUNNING state, the Lambda function will send the continuation token back to the CodePipeline action. This will cause CodePipeline to call the Lambda function again a few seconds later. If the state machine has SUCCEEDED, then the Lambda function will notify the CodePipeline action that the action has succeeded. In any other case (FAILURE, TIMED-OUT, or ABORT), the Lambda function will fail the pipeline action.

This behavior is especially useful for developers who are building and debugging a new state machine because a bug in the state machine can potentially leave the pipeline action hanging for long periods of time until it times out. The Trigger Lambda function prevents this.

Also, by having the Trigger Lambda function as a means to decouple the pipeline and state machine, we make the state machine more reusable. It can be triggered from anywhere, not just from a CodePipeline action.

The Pipeline in CodePipeline

Our sample pipeline contains two simple stages: the Source stage represented by a CodeCommit Git repository and the Prod stage, which contains the Deploy action that invokes the Trigger Lambda function. When the state machine decides that the change set created must be rejected (because it replaces or deletes some the existing production resources), it fails the pipeline without performing any updates to the existing infrastructure. (See the failed Deploy action in red.) Otherwise, the pipeline action succeeds, indicating that the existing provisioned infrastructure was either created (first run) or updated without impacting any resources. (See the green Deploy stage in the pipeline on the left.)

The Pipeline in CodePipeline

The JSON spec for the pipeline’s Prod stage is shown here. We use the UserParameters attribute to pass the S3 bucket and state machine input file to the Lambda function. These parameters are action-specific, which means that we can reuse the state machine in another pipeline action.

{
  "name": "Prod",
  "actions": [
      {
          "inputArtifacts": [
              {
                  "name": "CodeCommitOutput"
              }
          ],
          "name": "Deploy",
          "actionTypeId": {
              "category": "Invoke",
              "owner": "AWS",
              "version": "1",
              "provider": "Lambda"
          },
          "outputArtifacts": [],
          "configuration": {
              "FunctionName": "StateMachineTriggerLambda",
              "UserParameters": "{\"s3Bucket\": \"codepipeline-StepFunctions-sample\", \"stateMachineFile\": \"state_machine_input.json\"}"
          },
          "runOrder": 1
      }
  ]
}

Conclusion

In this blog post, we discussed how state machines in AWS Step Functions can be used to handle workflow-driven actions. We showed how a Lambda function can be used to fully decouple the pipeline and the state machine and manage their interaction. The use of a state machine greatly simplified the associated CodePipeline action, allowing us to build a much simpler and cleaner pipeline while drilling down into the state machine’s execution for troubleshooting or debugging.

Here are two exercises you can complete by using the source code.

Exercise #1: Do not fail the state machine and pipeline action after inspecting a change set that deletes or replaces resources. Instead, create a stack with a different name (think of blue/green deployments). You can do this by creating a state machine transition between the “Safe to Update Infra?” and “Create Stack” stages and passing a new stack name as input to the “Create Stack” stage.

Exercise #2: Add wait logic to the state machine to wait until the change set completes its execution before allowing the state machine to proceed to the “Deployment Succeeded” stage. Use the stack creation case as an example. You’ll have to create a Lambda function (similar to the Lambda function that checks the creation status of a stack) to get the creation status of the change set.

Have fun and share your thoughts!

About the Author

Marcilio Mendonca is a Sr. Consultant in the Canadian Professional Services Team at Amazon Web Services. He has helped AWS customers design, build, and deploy best-in-class, cloud-native AWS applications using VMs, containers, and serverless architectures. Before he joined AWS, Marcilio was a Software Development Engineer at Amazon. Marcilio also holds a Ph.D. in Computer Science. In his spare time, he enjoys playing drums, riding his motorcycle in the Toronto GTA area, and spending quality time with his family.

Things Go Better With Step Functions

Post Syndicated from Jeff Barr original https://aws.amazon.com/blogs/aws/things-go-better-with-step-functions/

I often give presentations on Amazon’s culture of innovation, and start out with a slide that features a revealing quote from Amazon founder Jeff Bezos:

I love to sit down with our customers and to learn how we have empowered their creativity and to pursue their dreams. Earlier this year I chatted with Patrick from The Coca-Cola Company in order to learn how they used AWS Step Functions and other AWS services to support the Coke.com Vending Pass program. This program includes drink rewards earned by purchasing products at vending machines equipped to support mobile payments using the Coca-Cola Vending Pass. Participants swipe their NFC-enabled phones to complete an Apple Pay or Android Pay purchase, identifying themselves to the vending machine and earning credit towards future free vending purchases in the process

After the swipe, a combination of SNS topics and AWS Lambda functions initiated a pair of calls to some existing backend code to count the vending points and update the participant’s record. Unfortunately, the backend code was slow to react and had some timing dependencies, leading to missing updates that had the potential to confuse Vending Pass participants. The initial solution to this issue was very simple: modify the Lambda code to include a 90 second delay between the two calls. This solved the problem, but ate up process time for no good reason (billing for the use of Lambda functions is based on the duration of the request, in 100 ms intervals).

In order to make their solution more cost-effective, the team turned to AWS Step Functions, building a very simple state machine. As I wrote in an earlier blog post, Step Functions coordinate the components of distributed applications and microservices at scale, using visual workflows that are easy to build.

Coke built a very simple state machine to simplify their business logic and reduce their costs. Yours can be equally simple, or they can make use of other Step Function features such as sequential and parallel execution and the ability to make decisions and choose alternate states. The Coke state machine looks like this:

The FirstState and the SecondState states (Task states) call the appropriate Lambda functions while Step Functions implements the 90 second delay (a Wait state). This modification simplified their logic and reduced their costs. Here’s how it all fits together:

 

What’s Next
This initial success led them to take a closer look at serverless computing and to consider using it for other projects. Patrick told me that they have already seen a boost in productivity and developer happiness. Developers no longer need to wait for servers to be provisioned, and can now (as Jeff says) unleash their creativity and pursue their dreams. They expect to use Step Functions to improve the scalability, functionality, and reliability of their applications, going far beyond the initial use for the Coca-Cola Vending Pass. For example, Coke has built a serverless solution for publishing nutrition information to their food service partners using Lambda, Step Functions, and API Gateway.

Patrick and his team are now experimenting with machine learning and artificial intelligence. They built a prototype application to analyze a stream of photos from Instagram and extract trends in tastes and flavors. The application (built as a quick, one-day prototype) made use of Lambda, Amazon DynamoDB, Amazon API Gateway, and Amazon Rekognition and was, in Patrick’s words, a “big win and an enabler.”

In order to build serverless applications even more quickly, the development team has created an internal CI/CD reference architecture that builds on the Serverless Application Framework. The architecture includes a guided tour of Serverless and some boilerplate code to access internal services and assets. Patrick told me that this model allows them to easily scale promising projects from “a guy with a computer” to an entire development team.

Patrick will be on stage at AWS re:Invent next to my colleague Tim Bray. To meet them in person, be sure to attend SRV306 – State Machines in the Wild! How Customers Use AWS Step Functions.

Jeff;

Automating Amazon EBS Snapshot Management with AWS Step Functions and Amazon CloudWatch Events

Post Syndicated from Andy Katz original https://aws.amazon.com/blogs/compute/automating-amazon-ebs-snapshot-management-with-aws-step-functions-and-amazon-cloudwatch-events/

Brittany Doncaster, Solutions Architect

Business continuity is important for building mission-critical workloads on AWS. As an AWS customer, you might define recovery point objectives (RPO) and recovery time objectives (RTO) for different tier applications in your business. After the RPO and RTO requirements are defined, it is up to your architects to determine how to meet those requirements.

You probably store persistent data in Amazon EBS volumes, which live within a single Availability Zone. And, following best practices, you take snapshots of your EBS volumes to back up the data on Amazon S3, which provides 11 9’s of durability. If you are following these best practices, then you’ve probably recognized the need to manage the number of snapshots you keep for a particular EBS volume and delete older, unneeded snapshots. Doing this cleanup helps save on storage costs.

Some customers also have policies stating that backups need to be stored a certain number of miles away as part of a disaster recovery (DR) plan. To meet these requirements, customers copy their EBS snapshots to the DR region. Then, the same snapshot management and cleanup has to also be done in the DR region.

All of this snapshot management logic consists of different components. You would first tag your snapshots so you could manage them. Then, determine how many snapshots you currently have for a particular EBS volume and assess that value against a retention rule. If the number of snapshots was greater than your retention value, then you would clean up old snapshots. And finally, you might copy the latest snapshot to your DR region. All these steps are just an example of a simple snapshot management workflow. But how do you automate something like this in AWS? How do you do it without servers?

One of the most powerful AWS services released in 2016 was Amazon CloudWatch Events. It enables you to build event-driven IT automation, based on events happening within your AWS infrastructure. CloudWatch Events integrates with AWS Lambda to let you execute your custom code when one of those events occurs. However, the actions to take based on those events aren’t always composed of a single Lambda function. Instead, your business logic may consist of multiple steps (like in the case of the example snapshot management flow described earlier). And you may want to run those steps in sequence or in parallel. You may also want to have retry logic or exception handling for each step.

AWS Step Functions serves just this purpose―to help you coordinate your functions and microservices. Step Functions enables you to simplify your effort and pull the error handling, retry logic, and workflow logic out of your Lambda code. Step Functions integrates with Lambda to provide a mechanism for building complex serverless applications. Now, you can kick off a Step Functions state machine based on a CloudWatch event.

In this post, I discuss how you can target Step Functions in a CloudWatch Events rule. This allows you to have event-driven snapshot management based on snapshot completion events firing in CloudWatch Event rules.

As an example of what you could do with Step Functions and CloudWatch Events, we’ve developed a reference architecture that performs management of your EBS snapshots.

Automating EBS Snapshot Management with Step Functions

This architecture assumes that you have already set up CloudWatch Events to create the snapshots on a schedule or that you are using some other means of creating snapshots according to your needs.

This architecture covers the pieces of the workflow that need to happen after a snapshot has been created.

  • It creates a CloudWatch Events rule to invoke a Step Functions state machine execution when an EBS snapshot is created.
  • The state machine then tags the snapshot, cleans up the oldest snapshots if the number of snapshots is greater than the defined number to retain, and copies the snapshot to a DR region.
  • When the DR region snapshot copy is completed, another state machine kicks off in the DR region. The new state machine has a similar flow and uses some of the same Lambda code to clean up the oldest snapshots that are greater than the defined number to retain.
  • Also, both state machines demonstrate how you can use Step Functions to handle errors within your workflow. Any errors that are caught during execution result in the execution of a Lambda function that writes a message to an SNS topic. Therefore, if any errors occur, you can subscribe to the SNS topic and get notified.

The following is an architecture diagram of the reference architecture:

Creating the Lambda functions and Step Functions state machines

First, pull the code from GitHub and use the AWS CLI to create S3 buckets for the Lambda code in the primary and DR regions. For this example, assume that the primary region is us-west-2 and the DR region is us-east-2. Run the following commands, replacing the italicized text in <> with your own unique bucket names.

git clone https://github.com/awslabs/aws-step-functions-ebs-snapshot-mgmt.git

cd aws-step-functions-ebs-snapshot-mgmt/

aws s3 mb s3://<primary region bucket name> --region us-west-2

aws s3 mb s3://<DR region bucket name> --region us-east-2

Next, use the Serverless Application Model (SAM), which uses AWS CloudFormation to deploy the Lambda functions and Step Functions state machines in the primary and DR regions. Replace the italicized text in <> with the S3 bucket names that you created earlier.

aws cloudformation package --template-file PrimaryRegionTemplate.yaml --s3-bucket <primary region bucket name>  --output-template-file tempPrimary.yaml --region us-west-2

aws cloudformation deploy --template-file tempPrimary.yaml --stack-name ebsSnapshotMgmtPrimary --capabilities CAPABILITY_IAM --region us-west-2

aws cloudformation package --template-file DR_RegionTemplate.yaml --s3-bucket <DR region bucket name> --output-template-file tempDR.yaml  --region us-east-2

aws cloudformation deploy --template-file tempDR.yaml --stack-name ebsSnapshotMgmtDR --capabilities CAPABILITY_IAM --region us-east-2

CloudWatch event rule verification

The CloudFormation templates deploy the following resources:

  • The Lambda functions that are coordinated by Step Functions
  • The Step Functions state machine
  • The SNS topic
  • The CloudWatch Events rules that trigger the state machine execution

So, all of the CloudWatch event rules have been created for you by performing the preceding commands. The next section demonstrates how you could create the CloudWatch event rule manually. To jump straight to testing the workflow, see the “Testing in your Account” section. Otherwise, you begin by setting up the CloudWatch event rule in the primary region for the createSnapshot event and also the CloudWatch event rule in the DR region for the copySnapshot command.

First, open the CloudWatch console in the primary region.

Choose Create Rule and create a rule for the createSnapshot command, with your newly created Step Function state machine as the target.

For Event Source, choose Event Pattern and specify the following values:

  • Service Name: EC2
  • Event Type: EBS Snapshot Notification
  • Specific Event: createSnapshot

For Target, choose Step Functions state machine, then choose the state machine created by the CloudFormation commands. Choose Create a new role for this specific resource. Your completed rule should look like the following:

Choose Configure Details and give the rule a name and description.

Choose Create Rule. You now have a CloudWatch Events rule that triggers a Step Functions state machine execution when the EBS snapshot creation is complete.

Now, set up the CloudWatch Events rule in the DR region as well. This looks almost same, but is based off the copySnapshot event instead of createSnapshot.

In the upper right corner in the console, switch to your DR region. Choose CloudWatch, Create Rule.

For Event Source, choose Event Pattern and specify the following values:

  • Service Name: EC2
  • Event Type: EBS Snapshot Notification
  • Specific Event: copySnapshot

For Target, choose Step Functions state machine, then select the state machine created by the CloudFormation commands. Choose Create a new role for this specific resource. Your completed rule should look like in the following:

As in the primary region, choose Configure Details and then give this rule a name and description. Complete the creation of the rule.

Testing in your account

To test this setup, open the EC2 console and choose Volumes. Select a volume to snapshot. Choose Actions, Create Snapshot, and then create a snapshot.

This results in a new execution of your state machine in the primary and DR regions. You can view these executions by going to the Step Functions console and selecting your state machine.

From there, you can see the execution of the state machine.

Primary region state machine:

DR region state machine:

I’ve also provided CloudFormation templates that perform all the earlier setup without using git clone and running the CloudFormation commands. Choose the Launch Stack buttons below to launch the primary and DR region stacks in Dublin and Ohio, respectively. From there, you can pick up at the Testing in Your Account section above to finish the example. All of the code for this example architecture is located in the aws-step-functions-ebs-snapshot-mgmt AWSLabs repo.

Launch EBS Snapshot Management into Ireland with CloudFormation
Primary Region eu-west-1 (Ireland)

Launch EBS Snapshot Management into Ohio with CloudFormation
DR Region us-east-2 (Ohio)

Summary

This reference architecture is just an example of how you can use Step Functions and CloudWatch Events to build event-driven IT automation. The possibilities are endless:

  • Use this pattern to perform other common cleanup type jobs such as managing Amazon RDS snapshots, old versions of Lambda functions, or old Amazon ECR images—all triggered by scheduled events.
  • Use Trusted Advisor events to identify unused EC2 instances or EBS volumes, then coordinate actions on them, such as alerting owners, stopping, or snapshotting.

Happy coding and please let me know what useful state machines you build!

Automate Your IT Operations Using AWS Step Functions and Amazon CloudWatch Events

Post Syndicated from Andy Katz original https://aws.amazon.com/blogs/compute/automate-your-it-operations-using-aws-step-functions-and-amazon-cloudwatch-events/


Rob Percival, Associate Solutions Architect

Are you interested in reducing the operational overhead of your AWS Cloud infrastructure? One way to achieve this is to automate the response to operational events for resources in your AWS account.

Amazon CloudWatch Events provides a near real-time stream of system events that describe the changes and notifications for your AWS resources. From this stream, you can create rules to route specific events to AWS Step Functions, AWS Lambda, and other AWS services for further processing and automated actions.

In this post, learn how you can use Step Functions to orchestrate serverless IT automation workflows in response to CloudWatch events sourced from AWS Health, a service that monitors and generates events for your AWS resources. As a real-world example, I show automating the response to a scenario where an IAM user access key has been exposed.

Serverless workflows with Step Functions and Lambda

Step Functions makes it easy to develop and orchestrate components of operational response automation using visual workflows. Building automation workflows from individual Lambda functions that perform discrete tasks lets you develop, test, and modify the components of your workflow quickly and seamlessly. As serverless services, Step Functions and Lambda also provide the benefits of more productive development, reduced operational overhead, and no costs incurred outside of when the workflows are actively executing.

Example workflow

As an example, this post focuses on automating the response to an event generated by AWS Health when an IAM access key has been publicly exposed on GitHub. This is a diagram of the automation workflow:

AWS proactively monitors popular code repository sites for IAM access keys that have been publicly exposed. Upon detection of an exposed IAM access key, AWS Health generates an AWS_RISK_CREDENTIALS_EXPOSED event in the AWS account related to the exposed key. A configured CloudWatch Events rule detects this event and invokes a Step Functions state machine. The state machine then orchestrates the automated workflow that deletes the exposed IAM access key, summarizes the recent API activity for the exposed key, and sends the summary message to an Amazon SNS topic to notify the subscribers―in that order.

The corresponding Step Functions state machine diagram of this automation workflow can be seen below:

While this particular example focuses on IT automation workflows in response to the AWS_RISK_CREDENTIALS_EXPOSEDevent sourced from AWS Health, it can be generalized to integrate with other events from these services, other event-generating AWS services, and even run on a time-based schedule.

Walkthrough

To follow along, use the code and resources found in the aws-health-tools GitHub repo. The code and resources include an AWS CloudFormation template, in addition to instructions on how to use it.

Launch Stack into N. Virginia with CloudFormation

The Step Functions state machine execution starts with the exposed keys event details in JSON, a sanitized example of which is provided below:

{
    "version": "0",
    "id": "121345678-1234-1234-1234-123456789012",
    "detail-type": "AWS Health Event",
    "source": "aws.health",
    "account": "123456789012",
    "time": "2016-06-05T06:27:57Z",
    "region": "us-east-1",
    "resources": [],
    "detail": {
        "eventArn": "arn:aws:health:us-east-1::event/AWS_RISK_CREDENTIALS_EXPOSED_XXXXXXXXXXXXXXXXX",
        "service": "RISK",
        "eventTypeCode": "AWS_RISK_CREDENTIALS_EXPOSED",
        "eventTypeCategory": "issue",
        "startTime": "Sat, 05 Jun 2016 15:10:09 GMT",
        "eventDescription": [
            {
                "language": "en_US",
                "latestDescription": "A description of the event is provided here"
            }
        ],
        "affectedEntities": [
            {
                "entityValue": "ACCESS_KEY_ID_HERE"
            }
        ]
    }
}

After it’s invoked, the state machine execution proceeds as follows.

Step 1: Delete the exposed IAM access key pair

The first thing you want to do when you determine that an IAM access key has been exposed is to delete the key pair so that it can no longer be used to make API calls. This Step Functions task state deletes the exposed access key pair detailed in the incoming event, and retrieves the IAM user associated with the key to look up API activity for the user in the next step. The user name, access key, and other details about the event are passed to the next step as JSON.

This state contains a powerful error-handling feature offered by Step Functions task states called a catch configuration. Catch configurations allow you to reroute and continue state machine invocation at new states depending on potential errors that occur in your task function. In this case, the catch configuration skips to Step 3. It immediately notifies your security team that errors were raised in the task function of this step (Step 1), when attempting to look up the corresponding IAM user for a key or delete the user’s access key.

Note: Step Functions also offers a retry configuration for when you would rather retry a task function that failed due to error, with the option to specify an increasing time interval between attempts and a maximum number of attempts.

Step 2: Summarize recent API activity for key

After you have deleted the access key pair, you’ll want to have some immediate insight into whether it was used for malicious activity in your account. Another task state, this step uses AWS CloudTrail to look up and summarize the most recent API activity for the IAM user associated with the exposed key. The summary is in the form of counts for each API call made and resource type and name affected. This summary information is then passed to the next step as JSON. This step requires information that you obtained in Step 1. Step Functions ensures the successful completion of Step 1 before moving to Step 2.

Step 3: Notify security

The summary information gathered in the last step can provide immediate insight into any malicious activity on your account made by the exposed key. To determine this and further secure your account if necessary, you must notify your security team with the gathered summary information.

This final task state generates an email message providing in-depth detail about the event using the API activity summary, and publishes the message to an SNS topic subscribed to by the members of your security team.

If the catch configuration of the task state in Step 1 was triggered, then the security notification email instead directs your security team to log in to the console and navigate to the Personal Health Dashboard to view more details on the incident.

Lessons learned

When implementing this use case with Step Functions and Lambda, consider the following:

  • One of the most important parts of implementing automation in response to operational events is to ensure visibility into the response and resolution actions is retained. Step Functions and Lambda enable you to orchestrate your granular response and resolution actions that provides direct visibility into the state of the automation workflow.
  • This basic workflow currently executes these steps serially with a catch configuration for error handling. More sophisticated workflows can leverage the parallel execution, branching logic, and time delay functionality provided by Step Functions.
  • Catch and retry configurations for task states allow for orchestrating reliable workflows while maintaining the granularity of each Lambda function. Without leveraging a catch configuration in Step 1, you would have had to duplicate code from the function in Step 3 to ensure that your security team was notified on failure to delete the access key.
  • Step Functions and Lambda are serverless services, so there is no cost for these services when they are not running. Because this IT automation workflow only runs when an IAM access key is exposed for this account (which is hopefully rare!), the total monthly cost for this workflow is essentially $0.

Conclusion

Automating the response to operational events for resources in your AWS account can free up the valuable time of your engineers. Step Functions and Lambda enable granular IT automation workflows to achieve this result while gaining direct visibility into the orchestration and state of the automation.

For more examples of how to use Step Functions to automate the operations of your AWS resources, or if you’d like to see how Step Functions can be used to build and orchestrate serverless applications, visit Getting Started on the Step Functions website.