Further simplification of the ZIP publication implementation

A follow-up of PR opensearch-project#4156 that brings in further simplification of the ZIP publication implementation and new tests.

It is possible to remove some of the initialization code because the work is already handled by other library under the hood (most likely by NebulaPublishPlugin).

For instance the condition to test the `groupId` presence: `if (groupId == null)` was pointless. It was never `true`. If the `project.group` is not defined the publication task fails with an exception, if there is a custom `groupId` value setup in publication config then it overrides the `project.group` as well. Tests are provided to cover these use cases.

As for the new tests they cover the following cases:

- verify that the task "publishToMavenLocal" gets expected results. The inspiration for this comes from opensearch-project/opensearch-plugin-template-java#35

- verify that applying only the 'opensearch.pluginzip' is enough, because both the NebulaPublish and MavenPublishPlugin plugins are added explicitly and tasks are chained correctly

- verify that if the plugin is applied but no publication is defined then a message is printed for the user

Signed-off-by: Lukáš Vlček <lukas.vlcek@aiven.io>

CHANGELOG.md

@@ -44,6 +44,7 @@ Inspired from [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 - [Segment Replication] Update replicas to commit SegmentInfos instead of relying on SIS files from primary shards. ([#4402](https://github.com/opensearch-project/OpenSearch/pull/4402))
 - [CCR] Add getHistoryOperationsFromTranslog method to fetch the history snapshot from translogs ([#3948](https://github.com/opensearch-project/OpenSearch/pull/3948))
 - [Remote Store] Change behaviour in replica recovery for remote translog enabled indices ([#4318](https://github.com/opensearch-project/OpenSearch/pull/4318))
+- Further simplification of the ZIP publication implementation ([#4360](https://github.com/opensearch-project/OpenSearch/pull/4360))
 
 ### Deprecated
 
@@ -101,4 +102,4 @@ Inspired from [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 
 
 [Unreleased]: https://github.com/opensearch-project/OpenSearch/compare/2.2.0...HEAD
-[2.x]: https://github.com/opensearch-project/OpenSearch/compare/2.2.0...2.x
+[2.x]: https://github.com/opensearch-project/OpenSearch/compare/2.2.0...2.x

buildSrc/src/main/java/org/opensearch/gradle/pluginzip/Publish.java

@@ -9,83 +9,72 @@
 
 import org.gradle.api.Plugin;
 import org.gradle.api.Project;
-import org.gradle.api.logging.Logger;
-import org.gradle.api.logging.Logging;
 import org.gradle.api.publish.PublishingExtension;
 import org.gradle.api.publish.maven.MavenPublication;
-import org.gradle.api.publish.maven.plugins.MavenPublishPlugin;
 
 import java.nio.file.Path;
 import org.gradle.api.Task;
+import org.gradle.api.publish.maven.plugins.MavenPublishPlugin;
 
 public class Publish implements Plugin<Project> {
 
-    private static final Logger LOGGER = Logging.getLogger(Publish.class);
-
-    public final static String EXTENSION_NAME = "zipmavensettings";
+    // public final static String PLUGIN_ZIP_PUBLISH_POM_TASK = "generatePomFileForPluginZipPublication";
     public final static String PUBLICATION_NAME = "pluginZip";
     public final static String STAGING_REPO = "zipStaging";
-    public final static String PLUGIN_ZIP_PUBLISH_POM_TASK = "generatePomFileForPluginZipPublication";
-    public final static String LOCALMAVEN = "publishToMavenLocal";
     public final static String LOCAL_STAGING_REPO_PATH = "/build/local-staging-repo";
-    public String zipDistributionLocation = "/build/distributions/";
+    // TODO: Does the path ^^ need to use platform dependant file separators ?
+
+    private boolean isZipPublicationPresent(Project project) {
+        PublishingExtension pe = project.getExtensions().findByType(PublishingExtension.class);
+        if (pe == null) {
+            return false;
+        }
+        return pe.getPublications().findByName(PUBLICATION_NAME) != null;
+    }
 
-    public static void configMaven(Project project) {
+    private void addLocalMavenRepo(Project project) {
         final Path buildDirectory = project.getRootDir().toPath();
-        project.getPluginManager().apply(MavenPublishPlugin.class);
         project.getExtensions().configure(PublishingExtension.class, publishing -> {
             publishing.repositories(repositories -> {
                 repositories.maven(maven -> {
                     maven.setName(STAGING_REPO);
                     maven.setUrl(buildDirectory.toString() + LOCAL_STAGING_REPO_PATH);
                 });
             });
+        });
+    }
+
+    private void addZipArtifact(Project project) {
+        project.getExtensions().configure(PublishingExtension.class, publishing -> {
             publishing.publications(publications -> {
                 MavenPublication mavenZip = (MavenPublication) publications.findByName(PUBLICATION_NAME);
-
-                if (mavenZip == null) {
-                    mavenZip = publications.create(PUBLICATION_NAME, MavenPublication.class);
+                if (mavenZip != null) {
+                    mavenZip.artifact(project.getTasks().named("bundlePlugin"));
                 }
-
-                String groupId = mavenZip.getGroupId();
-                if (groupId == null) {
-                    // The groupId is not customized thus we get the value from "project.group".
-                    // See https://docs.gradle.org/current/userguide/publishing_maven.html#sec:identity_values_in_the_generated_pom
-                    groupId = getProperty("group", project);
-                }
-
-                String artifactId = project.getName();
-                String pluginVersion = getProperty("version", project);
-                mavenZip.artifact(project.getTasks().named("bundlePlugin"));
-                mavenZip.setGroupId(groupId);
-                mavenZip.setArtifactId(artifactId);
-                mavenZip.setVersion(pluginVersion);
             });
         });
     }
 
-    static String getProperty(String name, Project project) {
-        if (project.hasProperty(name)) {
-            Object property = project.property(name);
-            if (property != null) {
-                return property.toString();
-            }
-        }
-        return null;
-    }
-
     @Override
     public void apply(Project project) {
+        project.getPluginManager().apply("nebula.maven-base-publish");
+        project.getPluginManager().apply(MavenPublishPlugin.class);
         project.afterEvaluate(evaluatedProject -> {
-            configMaven(project);
-            Task validatePluginZipPom = project.getTasks().findByName("validatePluginZipPom");
-            if (validatePluginZipPom != null) {
-                project.getTasks().getByName("validatePluginZipPom").dependsOn("generatePomFileForNebulaPublication");
-            }
-            Task publishPluginZipPublicationToZipStagingRepository = project.getTasks()
-                .findByName("publishPluginZipPublicationToZipStagingRepository");
-            if (publishPluginZipPublicationToZipStagingRepository != null) {
-                publishPluginZipPublicationToZipStagingRepository.dependsOn("generatePomFileForNebulaPublication");
+            if (isZipPublicationPresent(project)) {
+                addLocalMavenRepo(project);
+                addZipArtifact(project);
+                Task validatePluginZipPom = project.getTasks().findByName("validatePluginZipPom");
+                if (validatePluginZipPom != null) {
+                    validatePluginZipPom.dependsOn("generatePomFileForNebulaPublication");
+                }
+                Task publishPluginZipPublicationToZipStagingRepository = project.getTasks()
+                    .findByName("publishPluginZipPublicationToZipStagingRepository");
+                if (publishPluginZipPublicationToZipStagingRepository != null) {
+                    publishPluginZipPublicationToZipStagingRepository.dependsOn("generatePomFileForNebulaPublication");
+                }
+            } else {
+                project.getLogger()
+                    .warn(String.format("Plugin 'opensearch.pluginzip' is applied but no '%s' publication is defined.", PUBLICATION_NAME));
             }
         });
     }