update-rust.yml

# A GitHub Actions workflow that regularly checks for new Rust toolchain release
# and creates a PR on new versions.
name: Rust Update

on:
  schedule:
    # check for new rust versions weekly
    - cron:  '30 3 * * FRI'

jobs:
  rust-update:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4

        # First, check rust GitHub releases for a new version. We assume that the
        # latest version's tag name is the version.
      - name: Check new rust version
        id: update
        run: |
          current_rust_version=$(cat ./rust-toolchain.toml | sed -n 's/^channel[[:space:]]*=[[:space:]]"\(.*\)"/\1/p')
          echo "current rust version '$current_rust_version'"
          release_data=$(curl --silent -H 'Accept: application/vnd.github.v3+json' https://api.github.com/repos/rust-lang/rust/releases/latest)
          latest_rust_version=$(echo -n "$release_data" | jq -cMr .tag_name)

          # The GitHub API has some hiccups, so we check the value before going further
          if [ -z "$latest_rust_version" ] || [ "$latest_rust_version" = "null" ]
          then
            echo "expected a rust version, got '$latest_rust_version'"
            echo "data received from API:"
            echo "$release_data"
            exit 1
          fi

          echo "latest rust version '$latest_rust_version'"

          if [ "$current_rust_version" != "$latest_rust_version" ]
          then
            echo rust toolchain needs an update
            sed -i -e "s/$current_rust_version/$latest_rust_version/g" ./rust-toolchain.toml
            echo "updated=1" >> "$GITHUB_OUTPUT"
          else
            echo "updated=0" >> "$GITHUB_OUTPUT"
          fi

          cat ./rust-toolchain.toml

        # If the rust-toolchain was updated, create a PR.
      - name: Create Pull Request
        if: ${{ steps.update.outputs.updated == '1' }}
        uses: peter-evans/create-pull-request@v6
        with:
          token: ${{ secrets.GIX_BOT_PAT }}
          base: main
          add-paths: ./rust-toolchain.toml
          commit-message: Update rust version
          committer: GitHub <noreply@github.com>
          author: gix-bot <gix-bot@users.noreply.github.com>
          branch: bot-rust-update
          delete-branch: true
          title: 'Update rust version'

        # Since the this is a scheduled job, a failure won't be shown on any
        # PR status. To notify the team, we send a message to our Slack channel on failure.
      - name: Notify Slack on failure
        uses: ./.github/actions/slack
        if: ${{ failure() }}
        with:
          WEBHOOK_URL: ${{ secrets.SLACK_WEBHOOK_URL }}
          MESSAGE: "Rust update failed"