Creating Links Between AWS Elastic Beanstalk Environments
As your application grows in size and complexity, you may want to split it into components that have different development and operational lifecycles. This allows you to manage and scale each component independently providing you with greater agility. One of the challenges of this approach is the requirement for sharing connection information between components. This can be solved with AWS Elastic Beanstalk environment links.
Elastic Beanstalk currently supports environment links for all platforms except Multicontainer Docker.
With environment links, you can specify the connections between your application’s component environments as named references. When you create an environment that defines a link, Elastic Beanstalk sets an environment variable with the same name as the link. The value of the variable is the endpoint that you can use to connect to the other component, which can be a web server or worker environment.
For example, if your application consists of a frontend that collects email addresses and a worker that sends a welcome email to the email addresses collected by the frontend, you can create a link to the worker in your frontend and have the frontend automatically discover the endpoint (queue URL) for your worker.
Define links to other environments in an environment manifest, a YAML formatted file named
env.yaml in the
root of your application source. The following manifest defines a link to an environment named
AWSConfigurationTemplateVersion: 220.127.116.11 EnvironmentLinks: "WORKERQUEUE": "worker"
When you create an environment with an application version that includes the above
environment manifest, Elastic Beanstalk looks for an environment named
worker that belongs to
the same application. If that environment exists, Elastic Beanstalk creates an environment property named
WORKERQUEUE. The value of
WORKERQUEUE is the Amazon SQS queue URL. The
frontend application can read this property in the same manner as an environment variable.
See Using Elastic Beanstalk Saved Configurations for details.
To use environment links, add an environment manifest to your application source and upload
it with the EB CLI, AWS CLI or an SDK. If you use the AWS CLI or an SDK, set the
process flag when you call
$ aws elasticbeanstalk create-application-version
--process--application-name my-app --version-label frontend-v1 --source-bundle S3Bucket="my-bucket",S3Key="front-v1.zip"
This option tells Elastic Beanstalk to validate the environment manifest and configuration files in your source bundle when you create the application version. The EB CLI sets this flag automatically when you have an environment manifest in your project directory.
Create your environments normally using any client. When you need to terminate environments,
terminate the environment with the link first. If an environment is linked to by another
environment, Elastic Beanstalk will prevent the linked environment from being terminated. To override this
protection, use the
ForceTerminate flag. This parameter is available in the AWS CLI
$ aws elasticbeanstalk terminate-environment