Add support for index level slice count setting

[Gankris96]

Description

Adds support for index level slice count setting. This slice count value will take precedence over the cluster level slice count value if set.

Related Issues

Resolves #15268

Check List

• [x ] Functionality includes testing.
• API changes companion pull request created, if applicable.
• Public documentation issue/PR created, if applicable. Created the issue here : [DOC] Document support for index level max_slice_count setting and search.concurrent_segment_search.mode setting documentation-website#8068

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For more information on following Developer Certificate of Origin and signing off your commits, please check here.

[github-actions]

❌ Gradle check result for e671e35: 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?

[neetikasinghal]

@Gankris96 looks like the gradle precommit is failing - u will have to run ./gradlew :server:spotlessApply to fix it.
Also, add a change log entry for this change.

[Gankris96]

Tested out locally by setting the setting as follows:

Index setting before update:

curl --location 'localhost:9200/movies/_settings?include_defaults=null' \
--data ''

{
    "movies": {
        "settings": {
            "index": {
                "replication": {
                    "type": "DOCUMENT"
                },
                "number_of_shards": "1",
                "provided_name": "movies",
                "creation_date": "1724263596286",
                "number_of_replicas": "1",
                "uuid": "AdlJhZC3ShqP1ZL9BRwqYg",
                "version": {
                    "created": "137217827"
                }
            }
        }
    }
}

curl --location --request PUT 'localhost:9200/movies/_settings' \
--header 'Content-Type: application/json' \
--data '{
    "index": {
    "search.concurrent.max_slice_count": 2
  }
}'

{
    "acknowledged": true
}

After update the index setting would look like:

curl --location 'localhost:9200/movies/_settings' \
--data ''

{
    "movies": {
        "settings": {
            "index": {
                "replication": {
                    "type": "DOCUMENT"
                },
                "search": {
                    "concurrent": {
                        "max_slice_count": "2"
                    }
                },
                "number_of_shards": "1",
                "provided_name": "movies",
                "creation_date": "1724263095594",
                "number_of_replicas": "1",
                "uuid": "Y6IkbrSkQbu2B6Orc6gnzQ",
                "version": {
                    "created": "137217827"
                }
            }
        }
    }
}

[jed326]

Can you add a changelog entry as well?

[Gankris96]

@jed326 Opened a docs issue here opensearch-project/documentation-website#8068

[github-actions]

❌ Gradle check result for c2f2401:

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 84071f2: 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?

[jed326]

❌ Gradle check result for 84071f2: 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?

@Gankris96 can you try to rebase from main to see if that fixes these?

[harishbhakuni]

Changes LGTM.

[github-actions]

❕ Gradle check result for 1b6be03: 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.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 71.93%. Comparing base (abb1041) to head (1b6be03).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##               main   #15336   +/-   ##
=========================================
  Coverage     71.93%   71.93%           
+ Complexity    63223    63221    -2     
=========================================
  Files          5214     5214           
  Lines        295938   295943    +5     
  Branches      42754    42754           
=========================================
+ Hits         212876   212887   +11     
+ Misses        65601    65514   -87     
- Partials      17461    17542   +81     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[neetikasinghal]

Other changes look good to me, please ensure to check my comment #15336 (comment) as a follow-up!

[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-15336-to-2.x
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 b6b04039ab9b05de4da50863503b68f6be74e424
# Push it to GitHub
git push --set-upstream origin backport/backport-15336-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-15336-to-2.x.

[jed326]

@Gankris96 can you manually backport?

[Gankris96]

@jed326 backport to 2.x pr #15371