chore: add GitHub Actions to kick-off release and block manual creation of PRs to the release branch (#1821)

Author: ameter

.github/workflows/block_manual_pr_release.yml

@@ -0,0 +1,33 @@
+# Blocks PRs targeting the release branch that are not created by the release GHA workflow.
+#
+# This works because workflows cannot trigger other workflows unless they call them directly.
+# As a result, this workflow will only run with a PR targeting release is manually created.
+#
+# https://docs.github.com/en/actions/using-workflows/triggering-a-workflow#triggering-a-workflow-from-a-workflow
+
+name: Block Manual PR to Release
+
+on:
+  pull_request:
+    branches:
+      - release
+
+permissions:
+  pull-requests: write
+
+jobs:
+  check:
+    name: Block Manual PR to Release
+    runs-on: ubuntu-latest
+
+    steps:      
+      - uses: actions/checkout@a12a3943b4bdde767164f792f33f40b04645d846
+
+      - name: Close PR
+        shell: bash
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          PR_NUMBER: ${{ github.event.pull_request.number }}
+        run: |
+          gh pr close $PR_NUMBER --comment "Invalid PR!  PRs targeting the release branch must be created by the GHA release workflow."
+          exit 1

.github/workflows/release.yml

@@ -0,0 +1,21 @@
+# Creates a PR to push main to release branch to kick-off the CircleCI release workflow
+name: Release Amplify iOS 
+
+on:
+  workflow_dispatch:
+
+permissions:
+  pull-requests: write
+
+jobs:
+  release:
+    name: Release
+    runs-on: macos-latest
+
+    steps:
+      - uses: actions/checkout@a12a3943b4bdde767164f792f33f40b04645d846
+
+      - name: Create PR to push main to release branch
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: "gh pr create --title 'chore: kickoff release' --body 'kickoff release' --head main --base release"