release.yml

name: Release
on:
  pull_request:
    paths: ['internal/version/version.go']
  push:
    branches: ['main']
    paths: ['internal/version/version.go']

jobs:
  validate:
    runs-on: ubuntu-latest
    permissions:
      contents: write # To be able to create draft releases
    steps:
      - name: Checkout
        uses: actions/checkout@v4
      - name: Setup go
        uses: actions/setup-go@v5
        with:
          cache-dependency-path: '**/*.sum'

      # Obtains the current configured version tag from source, and verifies it is a valid tag name.
      # Also checks whether the tag already exists.
      - name: Determine version
        id: version
        run: |-
          set -euo pipefail
          # From https://semver.org/#is-there-a-suggested-regular-expression-regex-to-check-a-semver-string, with added v prefix.
          VERSION_TAG_REGEX='^v(0|[1-9]\d*)\.(0|[1-9]\d*)\.(0|[1-9]\d*)(?:-((?:0|[1-9]\d*|\d*[a-zA-Z-][0-9a-zA-Z-]*)(?:\.(?:0|[1-9]\d*|\d*[a-zA-Z-][0-9a-zA-Z-]*))*))?(?:\+([0-9a-zA-Z-]+(?:\.[0-9a-zA-Z-]+)*))?$'
          version=$(grep -E "${VERSION_TAG_REGEX}" <(go run . version))
          echo "tag=${version}" >> "${GITHUB_OUTPUT}"
          if gh release view "${version}" --json isDraft; then
            echo "exists=true" >> "${GITHUB_OUTPUT}"
          else
            echo "exists=false" >> "${GITHUB_OUTPUT}"
          fi
        env:
          GH_TOKEN: ${{ github.token }}

      # If this is a pull request, and the release does not yet exist, the PR title must be "release: <tag>"
      - name: 'Pull Request title must be "release: ${{ steps.version.outputs.tag }}"'
        if: "github.event_name == 'pull_request' && steps.version.outputs.exists == 'false' && github.event.pull_request.title != 'release: ${{ steps.version.outputs.tag }}'"
        run: |-
          echo 'Please update the PR title to "release: ${{ steps.version.outputs.tag }}" (instead of "${{ github.event.pull_request.title }}")'
          exit 1

      # If the release does not yet exist, create a draft release targeting this commit.
      - name: Create draft release
        if: github.event_name == 'push' && steps.version.outputs.exists == 'false'
        run: |-
          gh release create --draft --generate-notes --target="${{ github.sha }}" --title="${{ steps.version.outputs.tag }}" ${{ contains(steps.version.outputs.tag, '-') && '--prerelease' || '' }}
        env:
          GH_TOKEN: ${{ github.token }}