Add workflow to auto-update codegen

Signed-off-by: Thomas Farr <tsfarr@amazon.com>

.github/workflows/code-generation.yml

@@ -1,10 +1,15 @@
 name: Code Generation
 
-on: [pull_request]
+on:
+  pull_request:
+  workflow_dispatch:
+  schedule:
+    - cron: '0 0 * * 1' # 00:00 UTC Weekly on Mondays
 
 jobs:
   up_to_date:
-    name: Ensure Generated Code Up To Date
+    name: Ensure Generated Code Is Up To Date
+    if: github.event_name == 'pull_request'
     runs-on: ubuntu-latest
     steps:
       - name: Checkout Java Client
@@ -18,9 +23,9 @@ jobs:
           cache: 'gradle'
 
       - name: Run Code Generator
-        run: ./gradlew clean :java-codegen:run
+        run: ./gradlew :java-codegen:run
 
-      - name: Check Has No Changes
+      - name: Check For Uncommitted Changes
         shell: bash -eo pipefail {0}
         run: |
           output=$(git status --porcelain)
@@ -31,4 +36,53 @@ jobs:
             echo "Dirty working directory"
             echo "$output"
             exit 1
-          fi
+          fi
+
+
+  update_spec:
+    name: Update Specification and Re-generate Code
+    if: github.event_name == 'workflow_dispatch' || (github.event_name == 'schedule' && github.repository == 'opensearch-project/opensearch-java')
+    runs-on: ubuntu-latest
+    permissions:
+      contents: write
+      pull-requests: write
+    steps:
+      - name: Checkout Java Client
+        uses: actions/checkout@v4
+
+      - name: Set up JDK
+        uses: actions/setup-java@v4
+        with:
+          java-version: 11
+          distribution: 'temurin'
+          cache: 'gradle'
+
+      - name: Download Latest Spec && Run Code Generator
+        run: ./gradlew :java-codegen:downloadLatestSpec :java-codegen:run
+
+      - name: Get Current Date
+        id: date
+        run: echo "date=$(date +'%Y-%m-%d')" >> $GITHUB_OUTPUT
+
+      - name: Generate GitHub App Token
+        if: github.repository == 'opensearch-project/opensearch-java'
+        id: github_app_token
+        uses: tibdex/github-app-token@v1.5.0
+        with:
+          app_id: ${{ secrets.APP_ID }}
+          private_key: ${{ secrets.APP_PRIVATE_KEY }}
+          installation_id: 22958780
+
+      - name: Create Pull Request
+        uses: peter-evans/create-pull-request@v6
+        with:
+          token: ${{ steps.github_app_token.outputs.token || secrets.GITHUB_TOKEN }}
+          commit-message: Re-generate client code using latest OpenSearch API specification (${{ steps.date.outputs.date }})
+          title: Re-generated client code using latest OpenSearch API specification
+          body: |
+            Re-generated client code using latest OpenSearch API specification.
+            Date: ${{ steps.date.outputs.date }}
+          branch: code-gen/${{ github.ref_name }}/update
+          signoff: true
+          labels: |
+            autocut

java-codegen/build.gradle.kts

@@ -13,6 +13,7 @@
 
 import com.github.jk1.license.ProjectData
 import com.github.jk1.license.render.ReportRenderer
+import de.undercouch.gradle.tasks.download.Download
 import java.io.FileWriter
 
 buildscript {
@@ -32,6 +33,7 @@ plugins {
     id("com.github.jk1.dependency-license-report") version "2.8"
     id("org.owasp.dependencycheck") version "9.2.0"
     id("com.diffplug.spotless") version "6.25.0"
+    id("de.undercouch.download") version "5.6.0"
 }
 apply(plugin = "opensearch.repositories")
 apply(plugin = "org.owasp.dependencycheck")
@@ -66,9 +68,16 @@ application {
     )
 }
 
+val localSpecification = "$projectDir/opensearch-openapi.yaml"
+
+tasks.create<Download>("downloadLatestSpec") {
+    src("https://github.com/opensearch-project/opensearch-api-specification/releases/download/main-latest/opensearch-openapi.yaml")
+    dest(localSpecification)
+}
+
 tasks.named<JavaExec>("run") {
     args = listOf(
-        "--input", "$projectDir/opensearch-openapi.yaml",
+        "--input", localSpecification,
         "--eclipse-config", "$rootDir/buildSrc/formatterConfig-generated.xml",
         "--output", "${project(":java-client").projectDir}/src/generated/java/"
     )