From b9400283fc04883920ad1ec03924c36cb3b4784e Mon Sep 17 00:00:00 2001
From: Peter Nied <petern@amazon.com>
Date: Tue, 1 Aug 2023 20:19:34 +0000
Subject: [PATCH] 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 <petern@amazon.com>
---
 .github/workflows/detect-breaking-change.yml | 19 +++++++++++
 CHANGELOG.md                                 |  1 +
 server/build.gradle                          | 36 ++++++++++++++++++++
 3 files changed, 56 insertions(+)
 create mode 100644 .github/workflows/detect-breaking-change.yml

diff --git a/.github/workflows/detect-breaking-change.yml b/.github/workflows/detect-breaking-change.yml
new file mode 100644
index 0000000000000..4472920ba6d54
--- /dev/null
+++ b/.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
\ No newline at end of file
diff --git a/CHANGELOG.md b/CHANGELOG.md
index a37976462b38e..79e06b9e09843 100644
--- a/CHANGELOG.md
+++ b/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))
diff --git a/server/build.gradle b/server/build.gradle
index 3fde1b745c546..3a458c2e22152 100644
--- a/server/build.gradle
+++ b/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"
+}
\ No newline at end of file