rust-toolchain-update.yml

name: Rust Toolchain Update Bot

on:
  schedule:
    # Run weekly on Mondays at 00:00 UTC
    - cron: '0 0 * * 1'

jobs:
  check-and-update:
    name: Check for Rust toolchain updates
    runs-on: ubuntu-24.04

    permissions:
      contents: write
      pull-requests: write
      actions: write

    steps:
      - name: Checkout Repository
        uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # 5.0.0
        with:
          token: ${{ secrets.GITHUB_TOKEN }}

      - name: Configure git
        run: |
          git config user.name "github-actions[bot]"
          git config user.email "41898282+github-actions[bot]@users.noreply.github.com"

      - name: Check for Rust toolchain update
        id: rust-check
        run: |
          set -e

          # Get latest stable Rust version
          curl -s "https://static.rust-lang.org/dist/channel-rust-stable.toml" > channel.toml
          LATEST_FULL=$(yq '.pkg.rust.version' channel.toml | sed 's/ (.*//')
          LATEST_MINOR=$(echo "$LATEST_FULL" | cut -d. -f1,2)

          # Get current version
          CURRENT=$(yq '.toolchain.channel' rust-toolchain.toml)

          echo "Current: $CURRENT, Latest: $LATEST_MINOR"

          if [ "$LATEST_MINOR" != "$CURRENT" ]; then
            echo "needs_update=true" >> $GITHUB_OUTPUT
            echo "new_version=$LATEST_MINOR" >> $GITHUB_OUTPUT
            echo "full_version=$LATEST_FULL" >> $GITHUB_OUTPUT
            echo "✅ Update available: $CURRENT → $LATEST_MINOR"
          else
            echo "needs_update=false" >> $GITHUB_OUTPUT
            echo "⭐ Already on latest version: $CURRENT"
          fi

      - name: Update toolchain file and create branch
        id: rust-update
        if: steps.rust-check.outputs.needs_update == 'true'
        env:
          NEW_VERSION: ${{ steps.rust-check.outputs.new_version }}
        run: |
          # Define commit title
          COMMIT_TITLE="build(rust): Update Rust toolchain to $NEW_VERSION"

          # Update rust-toolchain.toml
          sed -i 's/channel = "[0-9.]*"/channel = "'$NEW_VERSION'"/' rust-toolchain.toml

          # Create branch and commit
          BRANCH_NAME="rust-toolchain/update-to-$NEW_VERSION"
          git checkout -B "$BRANCH_NAME"
          git add rust-toolchain.toml
          git commit -m "$COMMIT_TITLE"
          git push origin "$BRANCH_NAME" --force

          # Set outputs for next step
          echo "branch_name=$BRANCH_NAME" >> $GITHUB_OUTPUT
          echo "commit_title=$COMMIT_TITLE" >> $GITHUB_OUTPUT

      - name: Create pull request
        if: steps.rust-check.outputs.needs_update == 'true'
        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # 8.0.0
        with:
          script: |
            const newVersion = '${{ steps.rust-check.outputs.new_version }}';
            const fullVersion = '${{ steps.rust-check.outputs.full_version }}';
            const branchName = '${{ steps.rust-update.outputs.branch_name }}';
            const commitTitle = '${{ steps.rust-update.outputs.commit_title }}';

            // Check if PR already exists
            try {
              const { data: existingPRs } = await github.rest.pulls.list({
                owner: context.repo.owner,
                repo: context.repo.repo,
                head: `${context.repo.owner}:${branchName}`,
                state: 'open'
              });

              if (existingPRs.length > 0) {
                console.log(`PR already exists: #${existingPRs[0].number}`);
                return;
              }
            } catch (error) {
              console.log('No existing PR found, creating new one');
            }

            // Create new PR
            const { data: pr } = await github.rest.pulls.create({
              owner: context.repo.owner,
              repo: context.repo.repo,
              title: commitTitle,
              head: branchName,
              base: '${{ github.ref_name }}',
              body: `Update Rust toolchain to ${newVersion} (${fullVersion}).

              **Changes:**
              - Update \`rust-toolchain.toml\` channel to \`${newVersion}\`

              **Release Notes:** https://github.com/rust-lang/rust/releases/tag/${fullVersion}

              ---
              🤖 *This PR was created automatically by the Rust toolchain update bot.*`
            });

            // Add labels
            await github.rest.issues.addLabels({
              owner: context.repo.owner,
              repo: context.repo.repo,
              issue_number: pr.number,
              labels: ['github_actions']
            });

            console.log(`Created PR #${pr.number}: ${pr.title}`);

            // Run the CI workflow on the PR branch. Needed because GITHUB_TOKEN
            // doesn't trigger workflows, except for workflow_dispatch.
            await github.rest.actions.createWorkflowDispatch({
              owner: context.repo.owner,
              repo: context.repo.repo,
              workflow_id: 'ci.yml',
              ref: branchName,
            });