Add Get QueryGroup API Logic

[ruai0511]

Description

This change introduces the Get QueryGroup API which we will use to enforce node level resiliency as part of this RFC: #12342. The draft PR opened for the API specs is: opensearch-project/opensearch-api-specification#356

The Get QueryGroup API schema is:

curl -XGET "localhost:9200/_wlm/query_group/"  // get all existing QueryGroups
curl -XGET "localhost:9200/_wlm/query_group/{name}"  // get the QueryGroup with name={name}

Check List

• New functionality includes testing.
  • All tests pass
• New functionality has been documented.
  • New functionality has javadoc added
• Failing checks are inspected and point to the corresponding known issue(s) (See: Troubleshooting Failing Builds)
• Commits are signed per the DCO using --signoff
• Commit changes are listed out in CHANGELOG.md file (See: Changelog)
• Public documentation issue/PR created

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.
For more information on following Developer Certificate of Origin and signing off your commits, please check here.

[github-actions]

✅ Gradle check result for d7a452a: SUCCESS

[github-actions]

✅ Gradle check result for 837a2bb: SUCCESS

[codecov]

Codecov Report

Attention: Patch coverage is 72.22222% with 20 lines in your changes missing coverage. Please review.

Project coverage is 71.96%. Comparing base (b316279) to head (d4615c7).
Report is 2 commits behind head on main.

Files	Patch %	Lines
...earch/plugin/wlm/rest/RestGetQueryGroupAction.java	0.00%	7 Missing ⚠️
...nsearch/plugin/wlm/action/GetQueryGroupAction.java	0.00%	3 Missing ⚠️
...search/plugin/wlm/action/GetQueryGroupRequest.java	76.92%	2 Missing and 1 partial ⚠️
...lugin/wlm/action/TransportGetQueryGroupAction.java	76.92%	2 Missing and 1 partial ⚠️
...pensearch/plugin/wlm/WorkloadManagementPlugin.java	0.00%	2 Missing ⚠️
...ugin/wlm/service/QueryGroupPersistenceService.java	88.88%	0 Missing and 1 partial ⚠️
...va/org/opensearch/cluster/metadata/QueryGroup.java	75.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main   #14709      +/-   ##
============================================
+ Coverage     71.80%   71.96%   +0.16%     
- Complexity    63090    63179      +89     
============================================
  Files          5207     5212       +5     
  Lines        295581   295649      +68     
  Branches      42690    42692       +2     
============================================
+ Hits         212248   212776     +528     
+ Misses        65901    65408     -493     
- Partials      17432    17465      +33     

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[github-actions]

❕ Gradle check result for 70eb0dc: UNSTABLE

Please review all flaky tests that succeeded after retry and create an issue if one does not already exist to track the flaky failure.

[github-actions]

❌ Gradle check result for 9379a6e: FAILURE

Please examine the workflow log, locate, and copy-paste the failure(s) below, then iterate to green. Is the failure a flaky test unrelated to your change?

[github-actions]

✅ Gradle check result for a7f8835: SUCCESS

[github-actions]

❌ Gradle check result for d4615c7: FAILURE

Please examine the workflow log, locate, and copy-paste the failure(s) below, then iterate to green. Is the failure a flaky test unrelated to your change?

[github-actions]

✅ Gradle check result for d4615c7: SUCCESS

[opensearch-trigger-bot]

The backport to 2.x failed:

The process '/usr/bin/git' failed with exit code 128

To backport manually, run these commands in your terminal:

# Navigate to the root of your repository
cd $(git rev-parse --show-toplevel)
# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add ../.worktrees/OpenSearch/backport-2.x 2.x
# Navigate to the new working tree
pushd ../.worktrees/OpenSearch/backport-2.x
# Create a new branch
git switch --create backport/backport-14709-to-2.x
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 a900a16ce8c076488324993ec963f6a6f0e9e269
# Push it to GitHub
git push --set-upstream origin backport/backport-14709-to-2.x
# Go back to the original working tree
popd
# Delete the working tree
git worktree remove ../.worktrees/OpenSearch/backport-2.x

Then, create a pull request where the base branch is 2.x and the compare/head branch is backport/backport-14709-to-2.x.

[jed326]

@ruai0511 please open a manual backport. Thanks!

[jainankitk]

@jed326 - Probably need to merge the create backport first? - #15227. We can trigger the backport workflow to see if it goes through then!

[jed326]

Makes sense, merged that one let me retrigger here

[jainankitk]

Nice, the trigger-bot succeeded after the create backport merge!