Support jvmArgumentOverrides

[siegfriedweber]

Description

Support jvmArgumentOverrides, see https://docs.stackable.tech/home/stable/concepts/overrides/#jvm-argument-overrides.

Users are accustomed from other operators to being able to set JVM arguments via jvmArgumentOverrides. When they intuitively try this with the OpenSearch operator, it has no effect.

Workaround

Additional JVM arguments can currently set with the environment variable OPENSEARCH_JAVA_OPTS. The arguments are just appended to the other ones. Removing or changing arguments is not possible at the moment.

For example, the Java heap memory is set to 1 GB by default. It can be increased as follows:

---
apiVersion: opensearch.stackable.tech/v1alpha1
kind: OpenSearchCluster
spec:
  nodes:
    roleGroups:
      data:
        config:
          resources:
            memory:
              limit: 4Gi
        envOverrides:
          OPENSEARCH_JAVA_OPTS: "-Xms3g -Xmx3g"