[Extensions] REST API to initialize an extension and dynamically load it

[owaiskazi19]

Description

Currently, extensions are initialized in OpenSearch by creating an extensions.yml file. This allows OpenSearch to load the extensions only during the bootstrap. The approach created a chicken-egg problem when the hostAddress and hostPort of the OpenSearch cluster is unknown to extension to send a communication request.

This PR

• creates a REST API to initialize an extension dynamically. OpenSearch will load the extension based on the request body and then make a communication call to the specific extension and the rest of the workflow will follow.
• cleans up the old mechanism of creating an extensions.yml file and loading the extensions from it.

Request:
_extensions/initialize

Body:

{
    "name": "ad-extension",
    "uniqueId": "ad-extension",
    "hostAddress": "127.0.0.1",
    "port": "4532",
    "version": "1.0",
    "opensearchVersion": "3.0.0",
    "minimumCompatibleVersion": "3.0.0",
    "dependencies": [{"uniqueId": "test1", "version": "2.0.0"}, {"uniqueId": "test2", "version": "3.0.0"}]
}

Related Issues

Resolves opensearch-project/opensearch-sdk-java#782

Check List

• New functionality includes testing.
  • All tests pass
• New functionality has been documented.
  • New functionality has javadoc added
• Commits are signed per the DCO using --signoff
• Commit changes are listed out in CHANGELOG.md file (See: Changelog)

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 (Jenkins) Run Completed with:

• RESULT: FAILURE ❌
• URL: https://build.ci.opensearch.org/job/gradle-check/17388/
• CommitID: 37cc044
  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?

[joshpalis]

doing an initial pass

[github-actions]

Gradle Check (Jenkins) Run Completed with:

• RESULT: FAILURE ❌
• URL: https://build.ci.opensearch.org/job/gradle-check/17387/
• CommitID: 440ab97
  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 (Jenkins) Run Completed with:

• RESULT: UNSTABLE ❕
• TEST FAILURES:

      1 org.opensearch.indices.replication.SegmentReplicationIT.testReplicationPostDeleteAndForceMerge

• URL: https://build.ci.opensearch.org/job/gradle-check/17389/
• CommitID: 3b9dde4
  Please review all flaky tests that succeeded after retry and create an issue if one does not already exist to track the flaky failure.

[codecov]

Codecov Report

Merging #8029 (f6928dd) into main (2d9a88c) will decrease coverage by 0.13%.
The diff coverage is 65.87%.

@@             Coverage Diff              @@
##               main    #8029      +/-   ##
============================================
- Coverage     70.99%   70.87%   -0.13%     
+ Complexity    56683    56607      -76     
============================================
  Files          4720     4721       +1     
  Lines        267590   267614      +24     
  Branches      39208    39218      +10     
============================================
- Hits         189984   189661     -323     
- Misses        61635    61980     +345     
- Partials      15971    15973       +2     

Impacted Files	Coverage Δ
...c/main/java/org/opensearch/bootstrap/Security.java	33.09% <ø> (+0.23%)	⬆️
.../src/main/java/org/opensearch/env/Environment.java	87.78% <ø> (+0.66%)	⬆️
...rch/extensions/rest/RestActionsRequestHandler.java	100.00% <ø> (ø)
...rch/extensions/rest/RestSendToExtensionAction.java	46.66% <ø> (ø)
server/src/main/java/org/opensearch/node/Node.java	85.83% <0.00%> (-0.02%)	⬇️
.../main/java/org/opensearch/action/ActionModule.java	95.03% <33.33%> (-0.47%)	⬇️
...org/opensearch/extensions/ExtensionDependency.java	66.66% <60.00%> (-7.02%)	⬇️
...a/org/opensearch/extensions/ExtensionsManager.java	43.50% <60.52%> (-13.57%)	⬇️
...extensions/rest/RestInitializeExtensionAction.java	73.01% <73.01%> (ø)
...g/opensearch/extensions/NoopExtensionsManager.java	42.85% <100.00%> (-19.65%)	⬇️

... and 463 files with indirect coverage changes

[github-actions]

Gradle Check (Jenkins) Run Completed with:

• RESULT: UNSTABLE ❕
• TEST FAILURES:

      1 org.opensearch.remotestore.SegmentReplicationUsingRemoteStoreIT.testDropPrimaryDuringReplication

• URL: https://build.ci.opensearch.org/job/gradle-check/17391/
• CommitID: 1dfba83
  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 (Jenkins) Run Completed with:

• RESULT: FAILURE ❌
• URL: https://build.ci.opensearch.org/job/gradle-check/18118/
• CommitID: 183a157
  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 (Jenkins) Run Completed with:

• RESULT: ❌
• URL: https://build.ci.opensearch.org/job/gradle-check/18121/
• CommitID: 183a157
  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 (Jenkins) Run Completed with:

• RESULT: UNSTABLE ❕
• TEST FAILURES:

      1 org.opensearch.search.backpressure.SearchBackpressureIT.testSearchShardTaskCancellationWithHighCpu

• URL: https://build.ci.opensearch.org/job/gradle-check/18122/
• CommitID: f6928dd
  Please review all flaky tests that succeeded after retry and create an issue if one does not already exist to track the flaky failure.

[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:

# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add ../.worktrees/backport-2.x 2.x
# Navigate to the new working tree
pushd ../.worktrees/backport-2.x
# Create a new branch
git switch --create backport/backport-8029-to-2.x
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 f015e6a6cc205d1300c852fc731aac90bac3d930
# Push it to GitHub
git push --set-upstream origin backport/backport-8029-to-2.x
# Go back to the original working tree
popd
# Delete the working tree
git worktree remove ../.worktrees/backport-2.x

Then, create a pull request where the base branch is 2.x and the compare/head branch is backport/backport-8029-to-2.x.