Use canonical hostname instead of ip by default

[aho135]

Fixes #16352

Description

druid.indexer.task.restoreTasksOnRestart does not work by default for Docker based deployments on Kubernetes

Updates druid.sh to use canonical hostname for druid.host by default. Allows users to set environment variable DRUID_SET_HOST_IP=1 to use IP instead

Release note

---

Key changed/added classes in this PR

• druid.sh

---

This PR has:

• been self-reviewed.
• added documentation for new or modified features or behaviors.
• a release note entry in the PR description.
• 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.
• been tested in a test Druid cluster.

[FrankChen021]

This changes the default behavior, need more people to review it.
IMO, in K8S deployment, it's reasonable to use host name instead of ip, changing to host name by default makes sense.

[cryptoe]

@georgew5656 could you please review this ?

[georgew5656]

@aho135 does this new default work okay with a raw docker run? i'm not exactly sure what
InetAddress.getLocalHost().getCanonicalHostName() returns there? i think it might be the container-id which might not work that well since its not reachable

[aho135]

@georgew5656 What did you have in mind as a raw docker run? The integration tests docker setup also uses InetAddress.getLocalHost().getCanonicalHostName() which just resolves to the name set in the docker-compose

[georgew5656]

if the integration tests are passing then this seems fine to me

[aho135]

Thanks for the review and approval @georgew5656! Do you know who would be the right person to tag for review and merge?

[georgew5656]

Thanks for the review and approval @georgew5656! Do you know who would be the right person to tag for review and merge?

i'd say if @FrankChen021 also thinks this is good to go I can merge it