helm: add Kubernetes discovery support

[adelcast]

The K8 discovery mechanism, enabled by the druid-kubernetes-extension, relies on each pod advertising its name and namespace on the env variables POD_NAME and POD_NAMESPACE [1]. Add env variables to all deployments/statefulsets.

[1] https://druid.apache.org/docs/latest/development/extensions-core/kubernetes.html

Signed-off-by: Alejandro del Castillo alejandro.delcastillo@ni.com

Description

Helm deployment is not compatible with the druid-kubernetes-extension since the extension relies on each pod advertising its name and namespace on the env variables POD_NAME and POD_NAMESPACE

Add POD_NAME and POD_NAMESPACE env variables to all deployments/statefulsets.

Release note

• Add K8 discovery support to helm charts.

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This PR has:

• [X ] been self-reviewed.
  • using the concurrency checklist (Remove this item if the PR doesn't have any relation to concurrency.)
• added documentation for new or modified features or behaviors.
• [ X] a release note entry in the PR description.
• added Javadocs for most classes and all non-trivial methods. Linked related entities via Javadoc links.
• added or updated version, license, or notice information in licenses.yaml
• added comments explaining the "why" and the intent of the code wherever would not be obvious for an unfamiliar reader.
• added unit tests or modified existing tests to cover new code paths, ensuring the threshold for code coverage is met.
• added integration tests.
• [ X] been tested in a test Druid cluster.

[abhishekagarwal87]

thank you for your contribution @adelcast