prepare-release.yml

name: Prepare release

on:
  workflow_dispatch:
    inputs:
      bump:
        description: "Which component of the version to increment"
        required: true
        default: "patch"
        type: choice
        options:
          - major
          - minor
          - patch

env:
  CARGO_TERM_COLOR: always

jobs:
  prepare-release:
    name: Prepare Release
    runs-on: pub-hk-ubuntu-22.04-small
    steps:
      - name: Get token for GH application (Linguist)
        uses: heroku/use-app-token-action@main
        id: generate-token
        with:
          app_id: ${{ vars.LINGUIST_GH_APP_ID }}
          private_key: ${{ secrets.LINGUIST_GH_PRIVATE_KEY }}

      - name: Checkout
        uses: actions/checkout@v4
        with:
          # We always want the version bump/changelog and resultant PR to target main, not the branch of the workflow_dispatch.
          ref: main
          # Using the GH application token here will configure the local git config for this repo with credentials
          # that can be used to make signed commits that are attributed to the GH application user
          token: ${{ steps.generate-token.outputs.app_token }}

      - name: Update Rust toolchain
        run: rustup update

      - name: Rust Cache
        uses: Swatinem/rust-cache@v2.7.3

      - name: Install cargo-edit
        run: cargo install cargo-edit

      - name: Record old crate version
        id: old-version
        run: echo "version=$(yq '.workspace.package.version' Cargo.toml)" >> "${GITHUB_OUTPUT}"

      - name: Bump crate versions
        # We use `--package libcnb` here to prevent the example and test buildpack crates from
        # having their versions bumped too. Since the libcnb package's version is set via the
        # root Cargo.toml's `workspace.package.version` field, all other publishable crates will
        # still have their versions bumped, even though they are not explicitly listed here.
        run: cargo set-version --package libcnb --bump '${{ inputs.bump }}'

      - name: Record new crate version
        id: new-version
        run: echo "version=$(yq '.workspace.package.version' Cargo.toml)" >> "${GITHUB_OUTPUT}"

      - name: Update changelog
        run: |
          OLD_VERSION='${{ steps.old-version.outputs.version }}'
          NEW_VERSION='${{ steps.new-version.outputs.version }}'
          DATE_TODAY="$(date --utc --iso-8601)"
          UNRELEASED_URL="https://github.com/${{ github.repository }}/compare/v${NEW_VERSION}...HEAD"
          NEW_VERSION_URL="https://github.com/${{ github.repository }}/compare/v${OLD_VERSION}...v${NEW_VERSION}"

          sed --in-place --regexp-extended \
            --expression "s~(^## \[Unreleased\])$~\1\n\n\n## [${NEW_VERSION}] - ${DATE_TODAY}~" \
            --expression "s~(^\[unreleased\]:) .*$~\1 ${UNRELEASED_URL}\n[${NEW_VERSION}]: ${NEW_VERSION_URL}~" \
            CHANGELOG.md

      - name: Upgrade in-range dependency versions
        run: cargo upgrade
    
      - name: Create pull request
        id: pr
        uses: peter-evans/create-pull-request@v6.0.0
        with:
          token: ${{ steps.generate-token.outputs.app_token }}
          title: Prepare release v${{ steps.new-version.outputs.version }}
          body: |
            Changes:
            https://github.com/${{ github.repository }}/compare/v${{ steps.old-version.outputs.version }}...main
          commit-message: Prepare release v${{ steps.new-version.outputs.version }}
          branch: prepare-release
          delete-branch: true
          committer: ${{ vars.LINGUIST_GH_APP_USERNAME }} <${{ vars.LINGUIST_GH_APP_EMAIL }}>
          author: ${{ vars.LINGUIST_GH_APP_USERNAME }} <${{ vars.LINGUIST_GH_APP_EMAIL }}>

      - name: Configure pull request
        if: steps.pr.outputs.pull-request-operation == 'created'
        run: gh pr merge --auto --squash "${{ steps.pr.outputs.pull-request-number }}"
        env:
          GH_TOKEN: ${{ steps.generate-token.outputs.app_token }}