Auto-generate release note (#2878)

.github/generate_release_note.sh

@@ -0,0 +1,19 @@
+#!/bin/bash
+
+# It checks if the tag is annotated, otherwise it fails.
+[ "$(git describe)" != "$(git describe --tags)" ] && echo "Tag must be annotated." && exit 1
+
+CHANGELOG=$1
+CURRENT_TAG=$(git describe --abbrev=0)
+PREVIOUS_TAG=$(git describe --abbrev=0 "$CURRENT_TAG"^)
+
+cat <<EOF > "$CHANGELOG"
+$(git tag -l --format='%(contents)' "$CURRENT_TAG")
+
+<details><summary><b>Changes</b></summary>
+
+$(git log --oneline --no-decorate "$PREVIOUS_TAG".."$CURRENT_TAG")
+
+**Full Changelog**: https://github.com/Azure/ARO-RP/compare/$PREVIOUS_TAG...$CURRENT_TAG
+</details>
+EOF

.github/workflows/release-note.yml

@@ -0,0 +1,29 @@
+name: release-note
+on:
+  push:
+    tags:
+      - v*
+permissions:
+  contents: write
+
+jobs:
+  build:
+    name: Create Release
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v3
+        with:
+          ref: ${{ github.ref }}
+          fetch-depth: 0
+          # ref and fetch-depth: 0 are required to retrieve tag annotations.
+          # (see https://github.com/actions/runner-images/issues/1717)
+      - name: Generate Changelog
+        run: ./.github/generate_release_note.sh ${{ github.workspace }}/CHANGELOG.txt
+      - name: Release
+        uses: softprops/action-gh-release@v1
+        with:
+          body_path: ${{ github.workspace }}/CHANGELOG.txt
+          name: Release ${{ github.ref_name }}
+          draft: false
+          prerelease: false