Gradle plugin support for dependencies in plugin descriptor properties

[rursprung]

Description

this is #17178 rebased and split in two commits, with better commit messages. all credits for the actual commit content go to @abseth-amzn (who doesn't seem to be working on OpenSearch anymore, thus the original PR has been abandoned for a long time).

the rest is copy & paste from the commit message:
PR #11441 added support for semver ranges in dependencies of plugins.
this now updates opensearchplugin (from
org.opensearch.gradle:build-tools) to support dependencies property
when building plugins. since most plugins do not create the
plugin-descriptor.properties file manually but instead use this gradle
plugin for it this means that so far dependencies was not really used.

dependencies also allows depending on opensearch (i.e. the core) and
it allows depending on a semver range - thus this finally allows
decoupling plugin releases from OpenSearch releases, i.e. plugins using
this instead of specifying an opensearch.version do not need a new
release for every new OpenSearch minor/patch release.

for existing plugins updating to the new gradle plugin version will just
generate an empty dependencies entry. so far, this would have then
caused the plugin to fail to load, however the previous commit has
modified this behaviour.
an alternative would be to not generate the entry at all if no
dependencies are specified, but then dependencies would be handled
differently to all other entries in the properties file. since the
gradle plugin is generally only updated together with the OpenSearch
version which the plugins support this should be ok to do (it's unlikely
that a plugin will use the gradle plugin 3.8.0 and generate a plugin
release for e.g. 3.7.0).

---

plugin info: support empty dependencies

so far, if a plugin provides a plugin-descriptor.properties with an
empty dependencies entry this will fail if opensearch.version is
also specified. however, an empty dependencies entry should not fail
this - it should behave as if it were not present.

Related Issues

resolves #13187
related to #11441

Check List

• Functionality includes testing.
• API changes companion pull request created, if applicable.
• Public documentation issue/PR created, if applicable.

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[github-actions]

PR Reviewer Guide 🔍

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🧪 PR contains tests

🔒 No security concerns identified

✅ No TODO sections

🔀 No multiple PR themes

⚡ Recommended focus areas for review Always-emitted empty dependencies The descriptor template now unconditionally writes dependencies=${dependencies}, which for existing plugins that don't set dependencies will produce dependencies= in the generated plugin-descriptor.properties. Combined with PluginInfo.readFromProperties treating a blank dependencies value as absent (via the new isBlank check), this works for the default case; however, if a plugin already sets opensearch.version via the extension AND leaves dependencies empty, the generated descriptor will contain both keys (one non-empty, one empty). The new logic handles this because isBlank is used, but note that any tooling consuming plugin-descriptor.properties externally may now see an unexpected empty dependencies= line. Confirm downstream tools tolerate the extra empty property. # 'dependencies': any dependencies specified by the plugin dependencies=${dependencies} Possible Issue When a plugin sets dependencies via the extension, opensearchVersion is forcibly cleared to ''. However, if a user has also set opensearch.version explicitly (e.g. via extension defaults), no error is raised at build time — the Gradle plugin silently drops it. This can mask misconfiguration; at minimum this should log a warning or fail the build, matching the runtime check in PluginInfo.readFromProperties which rejects specifying both. // Clear opensearch version if dependencies are specified if (extension1.dependencies != null && !extension1.dependencies.trim().isEmpty()) { properties.put('opensearchVersion', ''); }

[github-actions]

PR Code Suggestions ✨

Explore these optional code suggestions:

Category	Suggestion	Impact
General	Warn when overriding opensearchVersion silently When dependencies are specified, the code clears opensearchVersion but the plugin-descriptor.properties template still emits opensearch.version= with an empty value. Combined with a non-empty dependencies value, this correctly hits the new isBlank check in PluginInfo.readFromProperties. However, if a user provides both non-empty dependencies and an explicit opensearchVersion override at the extension level (currently sourced from VersionProperties), the silent overwrite may hide misconfigurations. Consider logging a warning when overriding, or fail the build if both are explicitly set by the user, to avoid surprising behavior. buildSrc/src/main/groovy/org/opensearch/gradle/plugin/PluginBuildPlugin.groovy [120-123] // Clear opensearch version if dependencies are specified if (extension1.dependencies != null && !extension1.dependencies.trim().isEmpty()) { + project.logger.info("Plugin '${extension1.name}' specifies 'dependencies'; clearing 'opensearchVersion' in plugin descriptor.") properties.put('opensearchVersion', ''); } Suggestion importance[1-10]: 4 __ Why: Adding a log message when clearing opensearchVersion is a minor improvement for observability but doesn't address functional issues. The suggestion is reasonable but low impact.	Low
	Normalize blank strings to null early Since opensearchVersionString may now be an empty/blank string (not just null), ensure downstream code paths and any later usages of opensearchVersionString treat blank as absent. The current branch is fine, but pass a normalized value (null when blank) to avoid subtle bugs in future maintenance. server/src/main/java/org/opensearch/plugins/PluginInfo.java [306-310] -if (!isBlank(opensearchVersionString)) { - opensearchVersionRanges.add(SemverRange.fromString(opensearchVersionString)); +final String normalizedOpenSearchVersion = isBlank(opensearchVersionString) ? null : opensearchVersionString; +if (normalizedOpenSearchVersion != null) { + opensearchVersionRanges.add(SemverRange.fromString(normalizedOpenSearchVersion)); } else { Map<String, String> dependenciesMap; try ( Suggestion importance[1-10]: 3 __ Why: Normalizing blank to null is a minor code quality improvement. The existing code with isBlank check is already correct, so this is a stylistic preference with limited impact.	Low

[cwperks]

Thank you for this PR @rursprung ! I have something similar open at #19680 and I think between the 2 of these they can help ease the maintenance burden on plugins.

[github-actions]

✅ Gradle check result for f013b87: SUCCESS

[codecov]

Codecov Report

❌ Patch coverage is 60.00000% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 73.58%. Comparing base (264b119) to head (f013b87).
⚠️ Report is 7 commits behind head on main.

Files with missing lines	Patch %	Lines
.../opensearch/gradle/plugin/PluginBuildPlugin.groovy	0.00%	1 Missing and 1 partial ⚠️
...earch/gradle/plugin/PluginPropertiesExtension.java	50.00%	2 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main   #22426      +/-   ##
============================================
+ Coverage     73.44%   73.58%   +0.13%     
- Complexity    76423    76543     +120     
============================================
  Files          6102     6102              
  Lines        346523   346530       +7     
  Branches      49875    49876       +1     
============================================
+ Hits         254504   254992     +488     
+ Misses        71800    71256     -544     
- Partials      20219    20282      +63     

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