release.yml

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

permissions: read-all

jobs:
  validate:
    name: Validate Release
    runs-on: ubuntu-latest
    permissions:
      contents: write # To be able to create draft releases
    steps:
      - name: Checkout
        uses: actions/checkout@eef61447b9ff4aafe5dcd4e0bbf5d482be7e7871 # v4
      - name: Setup go
        uses: actions/setup-go@0a12ed9d6a96ab950c8f026ed9f722fe0da7ef32 # v5
        with:
          go-version: stable
          cache-dependency-path: '**/go.mod'

      # 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 "${VERSION_TAG_REGEX}" <(go run . version | cut -d' ' -f 2))
          echo "tag=${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' && !fromJSON(steps.version.outputs.exists) && format('release: {0}', steps.version.outputs.tag) != github.event.pull_request.title"
        run: |-
          echo "Please update the PR title to \"release: ${{ steps.version.outputs.tag }}\" (instead of ${EVENT_PR_TITLE})"
          exit 1
        env:
          EVENT_PR_TITLE: ${{ toJSON(github.event.pull_request.title) }}

      # Release must not already exist (if the PR title suggests this is intended to be a release)
      - name: Release ${{ steps.version.outputs.tag }} already exists
        if: github.event_name == 'pull_request' && fromJSON(steps.version.outputs.exists) && startsWith(github.event.pull_request.title, 'release:')
        run: |-
          echo 'A release already exists for tag ${{ steps.version.outputs.tag }}. Please update to another version.'
          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 '${{ steps.version.outputs.tag }}' --draft --generate-notes --target='${{ github.sha }}' --title='${{ steps.version.outputs.tag }}' ${{ contains(steps.version.outputs.tag, '-') && '--prerelease' || '' }}
        env:
          GH_TOKEN: ${{ github.token }}