Micronaut provides two ways of accessing Elasticsearch: via the lower level RestClient or via the RestHighLevelClient. To initialize Elasticsearch in your project’s cluster so that it can be accessed by a Micronaut application, it is necessary to modify two files.

1. Add the Elasticsearch service 

In your .platform/services.yaml file, include Elasticsearch with a valid supported version:

    type: elasticsearch:7.9
    disk: 256

2. Add the Elasticsearch relationship 

In your .platform.app.yaml file, use the service name searchelastic to grant the application access to Elasticsearch via a relationship:

    essearch: "searchelastic:elasticsearch"

3. Export connection credentials to the environment 

Connection credentials for Elasticsearch, like any service, are exposed to the application container through the PLATFORM_RELATIONSHIPS environment variable from the deploy hook onward. Since this variable is a base64 encoded JSON object of all of your project’s services, you’ll likely want a clean way to extract the information specific to Elasticsearch into it’s own environment variables that can be easily used by Micronaut. On Platform.sh, custom environment variables can be defined programmatically in a .environment file using jq to do just that:

export ES_HOST=$(echo $PLATFORM_RELATIONSHIPS | base64 --decode | jq -r ".essearch[0].host")
export ES_PORT=$(echo $PLATFORM_RELATIONSHIPS | base64 --decode | jq -r ".essearch[0].port")
export JAVA_OPTS="-Xmx$(jq .info.limits.memory /run/config.json)m -XX:+ExitOnOutOfMemoryError"

4. Connect to Elasticsearch 

Commit that code and push. The Elasticsearch instance is ready to be connected from within the Micronaut application.