Upgrade the exporter to support OpenSearch 2.12.0

[cesium147]

Description

Describe your PR and add links to relevant issues.

---

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[lukas-vlcek]

I need to look at it, it might be related to java version used in CI. Currently, it is JDK 14
https://github.com/Aiven-Open/prometheus-exporter-plugin-for-opensearch/blob/main/.github/workflows/CI.yml#L15
but we might want to upgrade to 17 or 21.

[amirkkn]

Hi @lukas-vlcek,
we use this exporter in all of our infrastructure and due to a lot of bugs in opensearch v2.11 we must upgrade ASAP. Could you please give me an ETA for the release for 2.12.0? Thanks

[lukas-vlcek]

I am on it...

[lukas-vlcek]

LGTM

[lukas-vlcek]

@cesium147 I had to do one merge from main during review and now the PR passes but can not be merged... I am not sure why...

[lukas-vlcek]

@cesium147 What happened is that I had to upgrade to gradle 8.5 and at the same time I upgraded CI to JDK 17. See https://github.com/Aiven-Open/prometheus-exporter-plugin-for-opensearch/pull/253/commits
Now, your PR somehow does not want to be merged (and rebased) because I did one merge commit...

Do you think you can open a new PR and we will close this one? I am not really sure what is going on. I should not have been using GitHub web UI to manipulate commits... I am sorry.

If you create a new PR, you can add the Java 21 to the CI array like this:

jobs:
  build:
    strategy:
      matrix:
        os: [ubuntu-latest]
        java: [17, 21]

Or you can keep it just on Java 17. Both should be ok.

Other than that the upgrade is looking good.

[lukas-vlcek]

Great, thanks @cesium147 !

[grechaw]

Thank you all for your work on this. We love upgrading and the exporter is a critical piece of it.

[lukas-vlcek]

FYI: Plugin version 2.12.0.0 has been released. The following is a forum announcement: https://forum.opensearch.org/t/prometheus-exporter-plugin-2-12-0-0-released/18105