Only run release build when PR has certain label

Author: hasufell

.github/workflows/release.yaml

@@ -2,8 +2,6 @@ name: Build and release
 
 on:
   push:
-    branches:
-      - master
     tags:
       - 'v*'
       - 'cabal-install-*'
@@ -14,8 +12,35 @@ on:
     - cron: '0 0 * * *'
   workflow_dispatch:
 
+permissions:
+  pull-requests: read
+
+env:
+  BUILD_LABEL: "run release build"
+
 jobs:
+  check-pr-labels:
+    name: check PR labels
+    runs-on: ubuntu-latest
+    outputs:
+      run_release_workflow: ${{ steps.gen_output.outputs.run_release_workflow }}
+    steps:
+      - id: gen_output
+        run: |
+          if [ "${{ github.event_name }}" = 'pull_request' ] ; then
+            run_it=$(if gh api --jq '.labels.[].name' /repos/${{ github.repository }}/pulls/${{ github.event.number }} | grep --quiet '^${{ env.BUILD_LABEL }}$' ; then printf "%s" "yes" ; else printf "%s" "no" ; fi)
+            echo "${run_it}"
+            echo run_release_workflow="${run_it}" >> "$GITHUB_OUTPUT"
+          else
+            echo run_release_workflow="yes" >> "$GITHUB_OUTPUT"
+          fi
+        shell: bash
+        env:
+          GH_TOKEN: ${{ github.token }}
+
   release-workflow:
+    needs: ["check-pr-labels"]
+    if: ${{ needs.check-pr-labels.outputs.run_release_workflow == 'yes' }}
     uses: ./.github/workflows/reusable-release.yml
     with:
       branches: '["${{ github.ref }}"]'