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ElasticSearch Cleanup

This function deletes old ElasticSearch indexes, as described in this blog post.

It is intended for older versions of Amazon's managed Elasticsearch service, which did not provide any way to manage indexes. Recent versions support Index State Management, which allows extensive control of indexes.

This Lambda is designed to be triggered by a CloudWatch scheduled event. I recommend triggering during a low-use period, although the deletion operation seems to run pretty quickly.

Lambda Configuration

Runtime: Python 3.6+

Required Memory: 256 MB

Timeout: 15 sec

Environment variables:

  • ELASTIC_SEARCH_HOSTNAME: hostname of the ElasticSearch cluster
  • NUM_INDEXES_TO_KEEP: the number of indexes to retain
  • INDEX_PREFIX: used to identify indexes to delete (eg: "logstash-")
  • IAM session identity (AWS_ACCESS_KEY_ID, AWS_SECRET_ACCESS_KEY, AWS_SESSION_TOKEN, and AWS_REGION): these are used to configure the aws-requests-auth module. They are provided by the Lambda runtime but must be explicitly configured if you want to run locally. If using long-term (user) credentials, you can omit AWS_SESSION_TOKEN.

Permissions:

  • AWSLambdaBasicExecutionRole
  • es:ESHttpGet
  • es:ESHttpDelete

Third-party Modules:

Building and Deploying

The easiest way to build and deploy this Lambda is with make. The provided Makefile has three relevant targets:

  • build: builds the deployment bundle (elasticsearch_index_cleanup.zip) and stores it in the project directory. You would normally invoke this target only if you're making changes and want to upload manually.

  • upload: builds the deployment bundle and then uploads it to an S3 bucket. You must provide the name of the bucket when invoking this target; you can optionally give the bundle a different name:

    # option 1, use predefined key
make upload S3_BUCKET=my_deployment_bucket

# option 2, use explicit key
make upload S3_BUCKET=my_deployment_bucket S3_KEY=my_bundle_name.zip

  • deploy: builds the deployment bundle, uploads it to S3, and then creates a CloudFormation stack (by default named ElasticsearchIndexCleanup, which is also the name of the created Lamdba) that creates the Lambda and all related resources. You must provide basic connectivity information, and may override the stack (Lambda) name, configured index pattern and number of indexes to keep.

    # option 1: use defaults
make deploy S3_BUCKET=my_deployment_bucket ES_HOSTNAME=search-example-3hpfi5df2mw5m7trqp5qjmespm.us-east-1.es.amazonaws.com ES_ARN=arn:aws:es:us-east-1:123456789012:domain/example

# option 2: specify everything
make deploy STACK_NAME=MyElasticsearchCleaner S3_BUCKET=my_deployment_bucket S3_KEY=my_bundle_name.zip ES_HOSTNAME=search-example-3hpfi5df2mw5m7trqp5qjmespm.us-east-1.es.amazonaws.com ES_ARN=arn:aws:es:us-east-1:123456789012:domain/example INDEX_PREFIX=elb- INDEX_COUNT=7

The one thing that you can't change via the Makefile is the invocation schedule. To do that, you'll need to either edit the template, deploy it manually, or edit after deployed.