In this post, I show you how to create isolated AWS Cloud9 environments for your developers without requiring ingress (inbound) access from the internet. I also walk you through optional steps to further isolate your AWS Cloud9 environment by removing egress (outbound) access. Until recently, AWS Cloud9 required you to allow ingress Secure Shell (SSH) access from authorized AWS Cloud9 IP addresses. Now AWS Cloud 9 allows you to create and run your development environments within your isolated Amazon Virtual Private Cloud (Amazon VPC), without direct connectivity from the internet, adding an additional layer of security.
AWS Cloud9 is an integrated development environment (IDE) that lets you write, run, edit, and debug code using only a web browser. Developers who use AWS Cloud9 have access to an isolated environment where they can innovate, experiment, develop, and perform early testing without impacting the overall security and stability of other environments. By using AWS Cloud9, you can store your code securely in a version control system (like AWS CodeCommit), configure your AWS Cloud9 EC2 development environments to use encrypted Amazon Elastic Block Store (Amazon EBS) volumes, and share your environments within the same account.
Before enhanced virtual private cloud (VPC) support was available, AWS Cloud9 required you to allow ingress Secure Shell (SSH) access from authorized AWS Cloud9 IP addresses in order to use the IDE. The addition of private VPC support enables you to create and run AWS Cloud9 environments in private subnets without direct connectivity from the internet. You can use VPC security groups to configure the ingress and egress traffic that you allow, or choose to disallow all traffic.
When you create an AWS Cloud9 no-ingress EC2 instance (with access via Systems Manager) into a private subnet, its security group doesn’t have an ingress rule to allow incoming network traffic. The security group does, however, have an egress rule that permits egress traffic from the instance. AWS Cloud9 requires this to download packages and libraries to keep the AWS Cloud9 IDE up to date.
If you want to prevent egress connectivity in addition to ingress traffic for the instance, you can configure Systems Manager to use an interface VPC endpoint. This allows you to restrict egress connections from your environment and ensure the encrypted connections between the AWS Cloud9 EC2 instance and Systems Manager are carried over the AWS global network. The architecture of accessing your AWS Cloud9 instance using Systems Manager and interface VPC endpoints is shown in Figure 1.
Figure 1: Accessing AWS Cloud9 environment via AWS Systems Manager and Interface VPC Endpoints
Note: The use of interface VPC endpoints incurs an additional charge for each hour your VPC endpoints remain provisioned. This is in addition to the AWS Cloud9 EC2 instance cost.
You must have a VPC configured with an attached internet gateway, public and private subnets, and a network address translation (NAT) gateway created in your public subnet. Your VPC must also have DNS resolution and DNS hostnames options enabled. To learn more, you can visit Working with VPCs and subnets, Internet gateways, and NAT gateways.
AWS Cloud9 requires egress access to the internet for some features, including downloading required libraries or packages needed for updates to the IDE and running AWS Lambda functions. If you don’t want to allow egress internet access for your environment, you can create your VPC without an attached internet gateway, public subnet, and NAT gateway.
Implement the solution
To set up AWS Cloud9 with access via Systems Manager:
Optionally, if no egress access is required, set up interface VPC endpoints for Session Manager
Create a no-ingress Amazon EC2 instance for your AWS Cloud9 environment
(Optional) Set up interface VPC endpoints for Session Manager
Note: For no-egress environments only.
You can skip this step if you don’t need your VPC to restrict egress access. If you need your environment to restrict egress access, continue.
Interface endpoints allow you to privately access Amazon EC2 and System Manager APIs by using a private IP address. This also restricts all traffic between your managed instances, Systems Manager, and Amazon EC2 to the Amazon network. Using the interface VPC endpoint, you don’t need to set up an internet gateway, a NAT device, or a virtual private gateway.
To set up interface VPC endpoints for Session Manager
Create a VPC security group to allow ingress access over HTTPS (port 443) from the subnet where you will deploy your AWS Cloud9 environment. This is applied to your interface VPC endpoints to allow connections from your AWS Cloud9 instance to use Systems Manager.
By default, your AWS Cloud9 environment is created with a VPC security group with no ingress access and allowing egress access so the AWS Cloud9 IDE can download required libraries or packages needed for urgent updates to IDE plugins. You can optionally configure your AWS Cloud9 environment to restrict egress access by removing the egress rules in the security group. If you restrict egress access, some features won’t work (for example, the AWS Lambda plugin and updates to IDE plugins).
To use the console to create your AWS Cloud9 environment
Select Create environment on the top right of the console.
Enter a Name and Description.
Select Next step.
Select Create a new no-ingress EC2 instance for your environment (access via Systems Manager) as shown in Figure 3.
Figure 3: AWS Cloud9 environment settings
Select your preferred Instance type, Platform, and Cost-saving setting.
You can optionally configure the Network settings to select the Network (VPC) and private Subnet to create your AWS Cloud9 instance.
Select Next step.
Your AWS Cloud9 environment is ready to use. You can access your AWS Cloud9 environment console via Session Manager using encrypted connections over the AWS global network as shown in Figure 4.
Figure 4: AWS Cloud9 instance console access
You can see that this AWS Cloud9 connection is using Session Manager by navigating to the Session Manager console and viewing the active sessions as shown in Figure 5.
Figure 5: AWS Systems Manager Session Manager active sessions
Security teams are charged with providing secure operating environments without inhibiting developer productivity. With the ability to deploy your AWS Cloud9 environment instances in a private subnet, you can provide a seamless experience for developing applications using the AWS Cloud9 IDE while enabling security teams to enforce key security controls to protect their corporate networks and intellectual property.
If you have feedback about this post, submit comments in the Comments section below. If you have questions about this post, start a new thread on the AWS Cloud9 forum or contact AWS Support.
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Amazon Simple Notification Service (SNS) now supports VPC Endpoints (VPCE) via AWS PrivateLink. You can use VPC Endpoints to privately publish messages to SNS topics, from an Amazon Virtual Private Cloud (VPC), without traversing the public internet. When you use AWS PrivateLink, you don’t need to set up an Internet Gateway (IGW), Network Address Translation (NAT) device, or Virtual Private Network (VPN) connection. You don’t need to use public IP addresses, either.
Here’s how VPC Endpoints for SNS works. The following example is based on a banking system that processes mortgage applications. This banking system, which has been deployed to a VPC, publishes each mortgage application to an SNS topic. The SNS topic then fans out the mortgage application message to two subscribing AWS Lambda functions:
Save-Mortgage-Application stores the application in an Amazon DynamoDB table. As the mortgage application contains personally identifiable information (PII), the message must not traverse the public internet.
Save-Credit-Report checks the applicant’s credit history against an external Credit Reporting Agency (CRA), then stores the final credit report in an Amazon S3 bucket.
The following diagram depicts the underlying architecture for this banking system:
To protect applicants’ data, the financial institution responsible for developing this banking system needed a mechanism to prevent PII data from traversing the internet when publishing mortgage applications from their VPC to the SNS topic. Therefore, they created a VPC endpoint to enable their publisher Amazon EC2 instance to privately connect to the SNS API. As shown in the diagram, when the VPC endpoint is created, an Elastic Network Interface (ENI) is automatically placed in the same VPC subnet as the publisher EC2 instance. This ENI exposes a private IP address that is used as the entry point for traffic destined to SNS. This ensures that traffic between the VPC and SNS doesn’t leave the Amazon network.
Set up VPC Endpoints for SNS
The process for creating a VPC endpoint to privately connect to SNS doesn’t require code changes: access the VPC Management Console, navigate to the Endpoints section, and create a new Endpoint. Three attributes are required:
The Security Group (SG) to be associated with the endpoint network interface. The Security Group controls the traffic to the endpoint network interface from resources in your VPC. If you don’t specify a Security Group, the default Security Group for your VPC will be associated.
The SNS API is served through HTTP Secure (HTTPS), and encrypts all messages in transit with Transport Layer Security (TLS) certificates issued by Amazon Trust Services (ATS). The certificates verify the identity of the SNS API server when encrypted connections are established. The certificates help establish proof that your SNS API client (SDK, CLI) is communicating securely with the SNS API server. A Certificate Authority (CA) issues the certificate to a specific domain. Hence, when a domain presents a certificate that’s issued by a trusted CA, the SNS API client knows it’s safe to make the connection.
VPC Endpoints can increase the security of your pub/sub messaging use cases by allowing you to publish messages to SNS topics, from instances in your VPC, without traversing the internet. Setting up VPC Endpoints for SNS doesn’t require any code changes because the SNS API address remains the same.
With the advent of AWS PrivateLink, you can provide services to AWS customers directly in their Virtual Private Networks by offering cross-account SaaS solutions on private IP addresses rather than over the Internet.
Traffic that flows to the services you provide does so over private AWS networking rather than over the Internet, offering security and performance enhancements, as well as convenience. PrivateLink can tie in with the AWS Marketplace, facilitating billing and providing a straightforward consumption model to your customers.
The use cases are myriad, but, for this blog post, we’ll demonstrate a fictional order-processing resource. The resource accepts JSON data over a RESTful API, simulating an interface. This could easily be an existing application being considered for a PrivateLink-based consumption model. Consumers of this resource send JSON payloads representing new orders and the system responds with order IDs corresponding to newly-created orders in the system. In a real-world scenario, additional APIs, such as authentication, might also represent critical aspects of the system. This example will not demonstrate these additional APIs because they could be consumed over PrivateLink in a similar fashion to the API constructed in the example.
I’ll demonstrate how to expose the resource on a private IP address in a customer’s VPC. I’ll also explain an architecture leveraging PrivateLink and provide detailed instructions for how to set up such a service. Finally, I’ll provide an example of how a customer might consume such a service. I’ll focus not only on how to architect the solution, but also the considerations that drive architectural choices.
N.B.: Only two subnets and Availability Zones are shown per VPC for simplicity. Resources must cover all Availability Zones per Region, so that the application is available to all consumers in the region. The instructions in this post, which pertain to resources sitting in us-east-1 will detail the deployment of subnets in all six Availability Zones for this region.
This solution exposes an application’s HTTP-based API over PrivateLink in a provider’s AWS account. The application is a stateless web server running on Amazon Elastic Compute Cloud (EC2) instances. The provider places instances within a virtual private network (VPC) consisting of one private subnet per Availability Zone (AZ). Each AZ contains a subnet. Instances populate each subnet inside of Auto Scaling Groups (ASGs), maintaining a desired count per subnet. There is one ASG per subnet to ensure that the service is available in each AZ. An internal Network Load Balancer (NLB) sits in front of the entire fleet of application instances and an endpoint service is connected with the NLB.
In the customer’s AWS account, they create an endpoint that consumes the endpoint service from the provider’s account. The endpoint exposes an Elastic Network Interface (ENI) in each subnet the customer desires. Each ENI is assigned an IP address within the CIDR block associated with the subnet, for any number of subnets in any number of AZs within the region, for each customer.
PrivateLink facilitates cross-account access to services so the customer can use the provider’s service, feeding it data that exist within the customer’s account while using application logic and systems that run in the provider’s account. The routing between accounts is over private networking rather than over the Internet.
Though this example shows a simple, stateless service running on EC2 and sitting behind an NLB, many kinds of AWS services can be exposed through PrivateLink and can serve as pathways into a provider’s application, such as Amazon Kinesis Streams, Amazon EC2 Container Service, Amazon EC2 Systems Manager, and more.
Using PrivateLink to Establish a Service for Consumption
Building a service to be consumed through PrivateLink involves a few steps:
Build a VPC covering all AZs in region with private subnets
Create a NLB, listener, and target group for instances
Create a launch configuration and ASGs to manage the deployment of Amazon
EC2 instances in each subnet
Launch an endpoint service and connect it with the NLB
Tie endpoint-request approval with billing systems or the AWS Marketplace
Provide the endpoint service in multiple regions
Step 1: Build a VPC and private subnets
Start by determining the network you will need to serve the application. Keep in mind, that you will need to serve the application out of each AZ within any region you choose. Customers will expect to consume your service in multiple AZs because AWS recommends they architect their own applications to span across AZs for fault-tolerance purposes.
Additionally, anything less than full coverage across all AZs in a single region will not facilitate straightforward consumption of your service because AWS does not guarantee that a single AZ will carry the same name across accounts. In fact, AWS randomizes AZ names across accounts to ensure even distribution of independent workloads. Telling customers, for example, that you provide a service in us-east-1a may not give them sufficient information to connect with your service.
The solution is to serve your application in all AZs within a region because this guarantees that no matter what AZs a customer chooses for endpoint creation, that customer is guaranteed to find a running instance of your application with which to connect.
You can lay the foundations for doing this by creating a subnet in each AZ within the region of your choice. The subnets can be private because the service, exposed via PrivateLink, will not provide any publicly routable APIs.
This example uses the us-east-1 region. If you use a different region, the number of AZs may vary, which will change the number of subnets required, and thus the size of the IP address range for your VPC may require adjustments.
The example above creates a VPC with 128 IP addresses starting at 10.3.0.0. Each subnet will contain 16 IP addresses, using a total of 96 addresses in the space. Allocating a sufficient block of addresses requires some planning (though you can make adjustments later if needed). I’d suggest an equally-sized address space in each subnet because the provided service should embody the same performance, availability, and functionality regardless of which AZ your customers choose. Each subnet will need a sufficient address space to accommodate the number of instances you run within it. Additionally, you will need enough space to allow for one IP address per subnet to assign to that subnet’s NLB node’s Elastic Network Interface (ENI).
In this simple example, 16 IP addresses per subnet are enough because we will configure ASGs to maintain two instances each and the NLB requires one ENI. Each subnet reserves five IP addresses for internal purposes, for a total of eight IP addresses needed in each subnet to support the service.
Next, create the private subnets for each Availability Zone. The following demonstrates the creation of the first subnet, which sits in the us-east-1a AZ:
Repeat this step for each remaining AZ. If using the us-east-1 region, you will need to create private subnets in all AZs as follows:
For the purpose of this example, the subnets can leverage the default route table, as it contains a single rule for routing requests to private IP addresses in the VPC, as follows:
In a real-world case, additional routing may be required. For example, you may need additional routes to support VPC peering to access dependencies in other VPCs, connectivity to on-premises resources over DirectConnect or VPN, Internet-accessible dependencies via NAT, or other scenarios.
Security Group Creation
Instances will need to be placed in a security group that allows traffic from the NLB nodes that sit in each subnet.
All instances running the service should be in a security group accepting TCP traffic on the traffic port from any other IP address in the VPC. This will allow the NLB to forward traffic to those instances because the NLB nodes sit in the VPC and are assigned IP addresses in the subnets. In this example, the order processing server running on each instance exposes a service on port 3000, so the security group rule covers this port.
Create a security group for instances:
aws ec2 create-security-group \
--group-name "service-sg" \
--description "Security group for service instances" \
Step 2: Create a Network Load Balancer, Listener, and Target Group
The service integrates with PrivateLink using an internal NLB which sits in front of instances that run the service.
Step 3: Create a Launch Configuration and Auto Scaling Groups
Each private subnet in the VPC will require its own ASG in order to ensure that there is always a minimum number of instances in each subnet.
A single ASG spanning all subnets will not guarantee that every subnet contains the appropriate number of instances. For example, while a single ASG could be configured to work across six subnets and maintain twelve instances, there is no guarantee that each of the six subnets will contain two instances. To guarantee the appropriate number of instances on a per-subnet basis, each subnet must be configured with its own ASG.
New instances should be automatically created within each ASG based on a single launch configuration. The launch configuration should be set up to use an existing Amazon Machine Image (AMI).
This post presupposes you have an AMI that can be used to create new instances that serve the application. There are only a few basic assumptions to how this image is configured:
1. The image containes a web server that serves traffic (in this case, on port 3000) 2. The image is configured to automatically launch the web server as a daemon when the instance starts.
Repeat this process to create an ASG in each remaining subnet, using the same launch configuration and target group.
In this example, only two instances are created in each subnet. In a real-world scenario, additional instances would likely be recommended for both availability and scale. The ASGs use the provided launch configuration as a template for creating new instances.
When creating the ASGs, the ARN of the target group for the NLB is provided. This way, the ASGs automatically register newly-created instances with the target group so that the NLB can begin sending traffic to them.
Step 4: Launch an endpoint service and connect with NLB
Now, expose the service via PrivateLink with an endpoint service, providing the ARN of the NLB:
This endpoint service is configured to require acceptance. This means that new consumers who attempt to add endpoints that consume it will have to wait for the provider to allow access. This provides an opportunity to control access and integrate with billing systems that monetize the provided service.
Step 5: Tie endpoint request approval with billing system or the AWS Marketplace
If you’re maintaining your service as a private service, any account that is intended to have access must be whitelisted before it can find the endpoint service and create an endpoint to consume it.
For more information on listing a PrivateLink service in the AWS Marketplace, see How to List Your Product in AWS Marketplace (https://aws.amazon.com/blogs/apn/how-to-list-your-product-in-aws-marketplace/).
Most production-ready services offered through PrivateLink will require acceptance of Endpoint requests before customers can consume them. Typically, some level of automation around processing approvals is helpful. PrivateLink can publish on a Simple Notification Service (SNS) topic when customers request approval.
Setting this up requires two steps:
1. Create a new SNS topic 2. Create an endpoint connection notification that publishes to the SNS topic.
Each is discussed below.
Create an SNS Topic
First, create a new SNS Topic that can receive messages relating to endpoint service access requests:
A billing system may ultimately tie in with request approval. This can also be done manually, which may be less useful, but is illustrative. As an example, assume that a customer account has already requested an endpoint to consume the service. The customer can be accepted manually, as follows:
At this point, the consumer can begin consuming the service.
Step 6: Take the Service Across Regions
In distributing SaaS via PrivateLink, providers may have to have to think about how to make their services available in different regions because Endpoint Services are only available within the region where they are created. Customers who attempt to consume Endpoint Services will not be able to create Endpoints across regions.
Rather than saddling consumers with the responsibility of making the jump across regions, we recommend providers work to make services available where their customers consume. They are in a better position to adapt their architectures to multiple regions than customers who do not know the internals of how providers have designed their services.
There are several architectural options that can support multi-region adaptation. Selection among them will depend on a number of factors, including read-to-write ratio, latency requirements, budget, amenability to re-architecture, and preference for simplicity.
Generally, the challenge in providing multi-region SaaS is in instantiating stateful components in multiple regions because the data on which such components depend are hard to replicate, synchronize, and access with low latency over large geographical distances.
Of all stateful components, perhaps the most frequently encountered will be databases. Some solutions for overcoming this challenge with respect to databases are as follows:
1. Provide a master in a single region; provide read replicas in every region. 2. Provide a master in every region; assign each tenant to one master only. 3. Create a full multi-master architecture; replicate data efficiently. 4. Rely on a managed service for replicating data cross-regionally (e.g., DynamoDB Global Tables).
Stateless components can be provisioned in multiple regions more easily. In this example, you will have to re-create all of the VPC resources—including subnets, Routing Tables, Security Groups, and Endpoint Services—as well as all EC2 resources—including instances, NLBs, Listeners, Target Groups, ASGs, and Launch Configurations—in each additional region. Because of the complexity in doing so, in addition to the significant need to keep regional configurations in-sync, you may wish to explore an orchestration tool such as CloudFormation, rather than the command line.
Regardless of what orchestration tooling you choose, you will need to copy your AMI to each region in which you wish to deploy it. Once available, you can build out your service in that region much as you did in the first one.
The response will include an attribute called VpcEndpoint.DnsEntries. The service can be accessed at each of the DNS names in the output under any of the entries there. Before the consumer can access the endpoint service, the provider has to accept the Endpoint.
Access Endpoint Via Custom DNS Names
When creating a new Endpoint, the consumer will receive named endpoint addresses in each AZ where the Endpoint is created, plus a named endpoint that is AZ-agnostic. For example:
The consumer can use Route53 to provide a custom DNS name for the service. This not only allows for using cleaner service names, but also enables the consumer to leverage the traffic management features of Route53, such as fail-over routing.
First, the the consumer must enable DNS Hostnames and DNS Support on the VPC within which the Endpoint was created. The consumer should start by enabling DNS Hostnames:
After the VPC is properly configured to work with Route53, the consumer should either select an existing hosted zone or create a new one. Assuming one has not already been created, the consumer should create one as follows:
In the request, the consumer specifies the DNS name, VPC ID, region, and flags the hosted zone as private. Additionally, the consumer must provide a “caller reference” which is a unique ID of the request that can be used to identify it in subsequent actions if the request fails.
Next, the consumer should create a JSON file corresponding to a batch of record change requests. In this file, the consumer can specify the name of the endpoint, as well as a CNAME pointing to the AZ-agnostic DNS name of the Endpoint:
At this point, the Endpoint can be consumed at http://order-processor.endpoints.internal.
AWS PrivateLink is an exciting way to expose SaaS services to customers. This article demonstrated how to expose an existing application on EC2 via PrivateLink in a customer’s VPC, as well as recommended architecture. Finally, it walked through the steps that a customer would have to go through to consume the service.
A customer has been successfully creating and running multiple Amazon Elasticsearch Service (Amazon ES) domains to support their business users’ search needs across products, orders, support documentation, and a growing suite of similar needs. The service has become heavily used across the organization. This led to some domains running at 100% capacity during peak times, while others began to run low on storage space. Because of this increased usage, the technical teams were in danger of missing their service level agreements. They contacted me for help.
This post shows how you can set up automated alarms to warn when domains need attention.
Amazon ES is a fully managed service that delivers Elasticsearch’s easy-to-use APIs and real-time analytics capabilities along with the availability, scalability, and security that production workloads require. The service offers built-in integrations with a number of other components and AWS services, enabling customers to go from raw data to actionable insights quickly and securely.
One of these other integrated services is Amazon CloudWatch. CloudWatch is a monitoring service for AWS Cloud resources and the applications that you run on AWS. You can use CloudWatch to collect and track metrics, collect and monitor log files, set alarms, and automatically react to changes in your AWS resources.
CloudWatch collects metrics for Amazon ES. You can use these metrics to monitor the state of your Amazon ES domains, and set alarms to notify you about high utilization of system resources. For more information, see Amazon Elasticsearch Service Metrics and Dimensions.
While the metrics are automatically collected, the missing piece is how to set alarms on these metrics at appropriate levels for each of your domains. This post includes sample Python code to evaluate the current state of your Amazon ES environment, and to set up alarms according to AWS recommendations and best practices.
There are two components to the sample solution:
es-check-cwalarms.py: This Python script checks the CloudWatch alarms that have been set, for all Amazon ES domains in a given account and region.
The sample code can also be found in the amazon-es-check-cw-alarms GitHub repo. The scripts are easy to extend or combine, as described in the section “Extensions and Adaptations”.
Assessing the current state
The first script, es-check-cwalarms.py, is used to give an overview of the configurations and alarm settings for all the Amazon ES domains in the given region. The script takes the following parameters:
python es-checkcwalarms.py -h
usage: es-checkcwalarms.py [-h] [-e ESPREFIX] [-n NOTIFY] [-f FREE][-p PROFILE] [-r REGION]
Checks a set of recommended CloudWatch alarms for Amazon Elasticsearch Service domains (optionally, those beginning with a given prefix).
-h, – help show this help message and exit
-e ESPREFIX, – esprefix ESPREFIX Only check Amazon Elasticsearch Service domains that begin with this prefix.
-n NOTIFY, – notify NOTIFY List of CloudWatch alarm actions; e.g. ['arn:aws:sns:xxxx']
-f FREE, – free FREE Minimum free storage (MB) on which to alarm
-p PROFILE, – profile PROFILE IAM profile name to use
-r REGION, – region REGION AWS region for the domain. Default: us-east-1
The script first identifies all the domains in the given region (or, optionally, limits them to the subset that begins with a given prefix). It then starts running a set of checks against each one.
The script can be run from the command line or set up as a scheduled Lambda function. For example, for one customer, it was deemed appropriate to regularly run the script to check that alarms were correctly set for all domains. In addition, because configuration changes—cluster size increases to accommodate larger workloads being a common change—might require updates to alarms, this approach allowed the automatic identification of alarms no longer appropriately set as the domain configurations changed.
The output shown below is the output for one domain in my account.
Starting checks for Elasticsearch domain iotfleet , version is 53
Iotfleet Automated snapshot hour (UTC): 0
Iotfleet Instance configuration: 1 instances; type:m3.medium.elasticsearch
Iotfleet Instance storage definition is: 4 GB; free storage calced to: 819.2 MB
iotfleet Desired free storage set to (in MB): 819.2
iotfleet WARNING: Not using VPC Endpoint
iotfleet WARNING: Does not have Zone Awareness enabled
iotfleet WARNING: Instance count is ODD. Best practice is for an even number of data nodes and zone awareness.
iotfleet WARNING: Does not have Dedicated Masters.
iotfleet WARNING: Neither index nor search slow logs are enabled.
iotfleet WARNING: EBS not in use. Using instance storage only.
iotfleet Alarm ok; definition matches. Test-Elasticsearch-iotfleet-ClusterStatus.yellow-Alarm ClusterStatus.yellow
iotfleet Alarm ok; definition matches. Test-Elasticsearch-iotfleet-ClusterStatus.red-Alarm ClusterStatus.red
iotfleet Alarm ok; definition matches. Test-Elasticsearch-iotfleet-CPUUtilization-Alarm CPUUtilization
iotfleet Alarm ok; definition matches. Test-Elasticsearch-iotfleet-JVMMemoryPressure-Alarm JVMMemoryPressure
iotfleet WARNING: Missing alarm!! ('ClusterIndexWritesBlocked', 'Maximum', 60, 5, 'GreaterThanOrEqualToThreshold', 1.0)
iotfleet Alarm ok; definition matches. Test-Elasticsearch-iotfleet-AutomatedSnapshotFailure-Alarm AutomatedSnapshotFailure
iotfleet Alarm: Threshold does not match: Test-Elasticsearch-iotfleet-FreeStorageSpace-Alarm Should be: 819.2 ; is 3000.0
The output messages fall into the following categories:
System overview, Informational: The Amazon ES version and configuration, including instance type and number, storage, automated snapshot hour, etc.
Free storage: A calculation for the appropriate amount of free storage, based on the recommended 20% of total storage.
Warnings: best practices that are not being followed for this domain. (For more about this, read on.)
Alarms: An assessment of the CloudWatch alarms currently set for this domain, against a recommended set.
The script contains an array of recommended CloudWatch alarms, based on best practices for these metrics and statistics. Using the array allows alarm parameters (such as free space) to be updated within the code based on current domain statistics and configurations.
For a given domain, the script checks if each alarm has been set. If the alarm is set, it checks whether the values match those in the array esAlarms. In the output above, you can see three different situations being reported:
Alarm ok; definition matches. The alarm set for the domain matches the settings in the array.
Alarm: Threshold does not match. An alarm exists, but the threshold value at which the alarm is triggered does not match.
WARNING: Missing alarm!! The recommended alarm is missing.
All in all, the list above shows that this domain does not have a configuration that adheres to best practices, nor does it have all the recommended alarms.
Setting up alarms
Now that you know that the domains in their current state are missing critical alarms, you can correct the situation.
To demonstrate the script, set up a new domain named “ver”, in us-west-2. Specify 1 node, and a 10-GB EBS disk. Also, create an SNS topic in us-west-2 with a name of “sendnotification”, which sends you an email.
Run the second script, es-create-cwalarms.py, from the command line. This script creates (or updates) the desired CloudWatch alarms for the specified Amazon ES domain, “ver”.
python es-create-cwalarms.py -r us-west-2 -e test -c ver -n "['arn:aws:sns:us-west-2:xxxxxxxxxx:sendnotification']"
EBS enabled: True type: gp2 size (GB): 10 No Iops 10240 total storage (MB)
Desired free storage set to (in MB): 2048.0
Successfully finished creating alarms!
As with the first script, this script contains an array of recommended CloudWatch alarms, based on best practices for these metrics and statistics. This approach allows you to add or modify alarms based on your use case (more on that below).
After running the script, navigate to Alarms on the CloudWatch console. You can see the set of alarms set up on your domain.
Because the “ver” domain has only a single node, cluster status is yellow, and that alarm is in an “ALARM” state. It’s already sent a notification that the alarm has been triggered.
In most cases, the alarm triggers due to an increased workload. The likely action is to reconfigure the system to handle the increased workload, rather than reducing the incoming workload. Reconfiguring any backend store—a category of systems that includes Elasticsearch—is best performed when the system is quiescent or lightly loaded. Reconfigurations such as setting zone awareness or modifying the disk type cause Amazon ES to enter a “processing” state, potentially disrupting client access.
Other changes, such as increasing the number of data nodes, may cause Elasticsearch to begin moving shards, potentially impacting search performance on these shards while this is happening. These actions should be considered in the context of your production usage. For the same reason I also do not recommend running a script that resets all domains to match best practices.
Avoid the need to reconfigure during heavy workload by setting alarms at a level that allows a considered approach to making the needed changes. For example, if you identify that each weekly peak is increasing, you can reconfigure during a weekly quiet period.
While Elasticsearch can be reconfigured without being quiesced, it is not a best practice to automatically scale it up and down based on usage patterns. Unlike some other AWS services, I recommend against setting a CloudWatch action that automatically reconfigures the system when alarms are triggered.
There are other situations where the planned reconfiguration approach may not work, such as low or zero free disk space causing the domain to reject writes. If the business is dependent on the domain continuing to accept incoming writes and deleting data is not an option, the team may choose to reconfigure immediately.
Extensions and adaptations
You may wish to modify the best practices encoded in the scripts for your own environment or workloads. It’s always better to avoid situations where alerts are generated but routinely ignored. All alerts should trigger a review and one or more actions, either immediately or at a planned date. The following is a list of common situations where you may wish to set different alarms for different domains:
Dev/test vs. production You may have a different set of configuration rules and alarms for your dev environment configurations than for test. For example, you may require zone awareness and dedicated masters for your production environment, but not for your development domains. Or, you may not have any alarms set in dev. For test environments that mirror your potential peak load, test to ensure that the alarms are appropriately triggered.
Differing workloads or SLAs for different domains You may have one domain with a requirement for superfast search performance, and another domain with a heavy ingest load that tolerates slower search response. Your reaction to slow response for these two workloads is likely to be different, so perhaps the thresholds for these two domains should be set at a different level. In this case, you might add a “max CPU utilization” alarm at 100% for 1 minute for the fast search domain, while the other domain only triggers an alarm when the average has been higher than 60% for 5 minutes. You might also add a “free space” rule with a higher threshold to reflect the need for more space for the heavy ingest load if there is danger that it could fill the available disk quickly.
“Normal” alarms versus “emergency” alarms If, for example, free disk space drops to 25% of total capacity, an alarm is triggered that indicates action should be taken as soon as possible, such as cleaning up old indexes or reconfiguring at the next quiet period for this domain. However, if free space drops below a critical level (20% free space), action must be taken immediately in order to prevent Amazon ES from setting the domain to read-only. Similarly, if the “ClusterIndexWritesBlocked” alarm triggers, the domain has already stopped accepting writes, so immediate action is needed. In this case, you may wish to set “laddered” alarms, where one threshold causes an alarm to be triggered to review the current workload for a planned reconfiguration, but a different threshold raises a “DefCon 3” alarm that immediate action is required.
The sample scripts provided here are a starting point, intended for you to adapt to your own environment and needs.
Running the scripts one time can identify how far your current state is from your desired state, and create an initial set of alarms. Regularly re-running these scripts can capture changes in your environment over time and adjusting your alarms for changes in your environment and configurations. One customer has set them up to run nightly, and to automatically create and update alarms to match their preferred settings.
Removing unwanted alarms
Each CloudWatch alarm costs approximately $0.10 per month. You can remove unwanted alarms in the CloudWatch console, under Alarms. If you set up a “ver” domain above, remember to remove it to avoid continuing charges.
Setting CloudWatch alarms appropriately for your Amazon ES domains can help you avoid suboptimal performance and allow you to respond to workload growth or configuration issues well before they become urgent. This post gives you a starting point for doing so. The additional sleep you’ll get knowing you don’t need to be concerned about Elasticsearch domain performance will allow you to focus on building creative solutions for your business and solving problems for your customers.
Dr. Veronika Megler is a senior consultant at Amazon Web Services. She works with our customers to implement innovative big data, AI and ML projects, helping them accelerate their time-to-value when using AWS.
Previously, applications running inside a VPC required internet access to connect to AWS KMS. This meant managing internet connectivity through internet gateways, Network Address Translation (NAT) devices, or firewall proxies. With support for Amazon VPC endpoints, you can now keep all traffic between your VPC and AWS KMS within the AWS network and avoid management of internet connectivity. In this blog post, I show you how to create and use an Amazon VPC endpoint for AWS KMS, audit the use of AWS KMS keys through the Amazon VPC endpoint, and build stricter access controls using key policies.
Create and use an Amazon VPC endpoint with AWS KMS
To get started, I will show you how to use the Amazon VPC console to create an endpoint in the US East (N. Virginia) Region, also known as us-east-1.
To create an endpoint in the US East (N. Virginia) Region:
Navigate to the Amazon VPC console. In the navigation pane, choose Endpoints, and then choose Create Endpoint.
Choose AWS services for Service category.
Choose the AWS KMS endpoint service, com.amazonaws.us-east-1.kms, from the Service Name list, as shown in the following screenshot.
Your VPC endpoint can span multiple Availability Zones, providing isolation and fault tolerance. Choose a subnet from each Availability Zone from which you want to connect. An elastic network interface for the VPC endpoint is created in each subnet that you choose, each with its own DNS hostname and private IP address.
If your VPC has DNS hostnames and DNS support enabled, choose Enable for this endpoint under Enable Private DNS Name to have applications use the VPC endpoint by default.
You use security groups to control access to your endpoint. Choose a security group from the list, or create a new one.
To finish creating the endpoint, choose Create endpoint. The console returns a VPC Endpoint ID. In our example, the VPC Endpoint ID is vpce-0c0052e3fbffdb450.
To connect to this endpoint, you need a DNS hostname that is generated for this endpoint. You can view these DNS hostnames by choosing the VPC Endpoint ID and then choosing the Details tab of the endpoint in the Amazon VPC console. One of the DNS hostnames for the endpoint that I created in the previous step is vpce-0c0052e3fbffdb450-afmosqu8.kms.us-east-1.vpce.amazonaws.com.
You can connect to AWS KMS through the VPC endpoint by using the AWS CLI or an AWS SDK. In this example, I use the following AWS CLI command to list all AWS KMS keys in the account in us-east-1.
If your VPC has DNS hostnames and DNS support enabled and you enabled private DNS names in the preceding steps, you can connect to your VPC endpoint by using the standard AWS KMS DNS hostname (https://kms.<region>.amazonaws.com), instead of manually configuring the endpoints in the AWS CLI or AWS SDKs. The AWS CLI and SDKs use this hostname by default to connect to KMS, so there’s nothing to change in your application to begin using the VPC endpoint.
You can monitor and audit AWS KMS usage through your VPC endpoint. Every request made to AWS KMS is logged by AWS CloudTrail. Now, when you use a VPC endpoint to make requests to AWS KMS, the endpoint ID appears in the CloudTrail log entries.
Restrict access using key policies
A good security practice to follow is least privilege: granting the fewest permissions required to complete a task. You can control access to your AWS KMS keys from a specific VPC endpoint by using AWS KMS key policies and AWS Identity and Access Management (IAM) policies. The aws:sourceVpce condition key lets you grant or restrict access to AWS KMS keys based on the VPC endpoint used. For example, the following example key policy allows a user to perform encryption operations with a key only when the request comes through the specified VPC endpoint (replace the placeholder AWS account ID with your own account ID, and the placeholder VPC endpoint ID with your own endpoint ID).
This policy works by including a Deny statement with a StringNotEquals condition. When a user makes a request to AWS KMS through a VPC endpoint, the endpoint’s ID is compared to the aws:sourceVpce value specified in the policy. If the two values are not the same, the request is denied. You can modify AWS KMS key policies in the AWS KMS console. For more information, see Modifying a Key Policy.
You also can control access to your AWS KMS keys from any endpoint running in one or more VPCs by using the aws:sourceVpc policy condition key. Suppose you have an application that is running in one VPC, but uses a second VPC for resource management functions. In the following example policy, AWS KMS key administrative actions can only be made from VPC vpc-12345678, and the key can only be used for cryptographic operations from VPC vpc-2b2b2b2b.
The previous examples show how you can limit access to AWS KMS API actions that are attached to a key policy. If you want to limit access to AWS KMS API actions that are not attached to a specific key, you have to use these VPC-related conditions in an IAM policy that refers to the desired AWS KMS API actions.
In this post, I have demonstrated how to create and use a VPC endpoint for AWS KMS, and how to use the aws:sourceVpc and aws:sourceVpce policy conditions to scope permissions to call various AWS KMS APIs. AWS KMS VPC endpoints provide you with more control over how your applications connect to AWS KMS and can save you from managing internet connectivity from your VPC.
If you have questions about this feature or anything else related to AWS KMS, start a new thread in the AWS KMS forum.
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