Detect breaking changes on pull requests

Adds a gradle task and github action to check for breaking changes made
to the APIs in server by running comparison against most resent snapshot
build on sonotype maven repository.

Uses japicmp to perform the comparison against the jar files, learn
more https://siom79.github.io/japicmp/

Signed-off-by: Peter Nied <[email protected]>

.github/workflows/detect-breaking-change.yml

@@ -0,0 +1,19 @@
+name: "Detect Breaking Changes"
+on: [push, pull_request]
+jobs:
+  detect-breaking-change:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v2
+    - uses: actions/setup-java@v2
+      with:
+        distribution: temurin # Temurin is a distribution of adoptium
+        java-version: 17
+    - uses: gradle/gradle-build-action@v2
+      with:
+        arguments: japicmp
+        gradle-version: 8.2.1
+        build-root-directory: server
+
+    - if: failure()
+      run: cat server/build/reports/japi.txt

CHANGELOG.md

@@ -81,6 +81,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Start replication checkpointTimers on primary before segments upload to remote store. ([#8221]()https://github.com/opensearch-project/OpenSearch/pull/8221)
 - [distribution/archives] [Linux] [x64] Provide the variant of the distributions bundled with JRE ([#8195]()https://github.com/opensearch-project/OpenSearch/pull/8195)
 - Add configuration for file cache size to max remote data ratio to prevent oversubscription of file cache ([#8606](https://github.com/opensearch-project/OpenSearch/pull/8606))
+- Detect breaking changes on pull requests ([#9044](https://github.com/opensearch-project/OpenSearch/pull/9044))
 
 ### Dependencies
 - Bump `org.apache.logging.log4j:log4j-core` from 2.17.1 to 2.20.0 ([#8307](https://github.com/opensearch-project/OpenSearch/pull/8307))

server/build.gradle

@@ -36,6 +36,7 @@ plugins {
   id('opensearch.publish')
   id('opensearch.internal-cluster-test')
   id('opensearch.optional-dependencies')
+  id('me.champeau.gradle.japicmp') version '0.4.2'
 }
 
 publishing {
@@ -408,3 +409,38 @@ tasks.named("sourcesJar").configure {
     duplicatesStrategy = DuplicatesStrategy.EXCLUDE
   }
 }
+
+/** Compares the current build against a snapshot build */
+tasks.register("japicmp", me.champeau.gradle.japicmp.JapicmpTask) {
+    oldClasspath.from(files("${buildDir}/snapshot/opensearch-${version}.jar"))
+    newClasspath.from(tasks.named('jar'))
+    onlyModified = true
+    failOnModification = true
+    ignoreMissingClasses = true
+    txtOutputFile = layout.buildDirectory.file("reports/japi.txt")
+    dependsOn downloadSnapshot
+}
+
+/** Downloads latest snapshot from maven repository */
+tasks.register("downloadSnapshot", Copy) {
+    def mavenSnapshotRepoUrl = "https://aws.oss.sonatype.org/content/repositories/snapshots/"
+    def groupId = "org.opensearch"
+    def artifactId = "opensearch"
+
+    repositories {
+        maven {
+            url mavenSnapshotRepoUrl
+        }
+    }
+
+    configurations {
+        snapshotArtifact
+    }
+
+    dependencies {
+        snapshotArtifact("${groupId}:${artifactId}:${version}:")
+    }
+
+    from configurations.snapshotArtifact
+    into "$buildDir/snapshot"
+}