combine-prs.yml

# Origin: https://github.com/hrvey/combine-prs-workflow
# Adapted to suit our purposes over time.

name: 'Combine PRs'

# Controls when the action will run - in this case triggered manually
on:
  workflow_dispatch:
    inputs:
      mustBeGreen:
        description: 'Only combine PRs that are green (status is success)'
        type: boolean
        required: true
        default: true
      combineBranchName:
        description: 'Name of the branch to combine PRs into'
        required: true
        default: 'combine-prs-branch'
      ignoreLabel:
        description: 'Exclude PRs with this label'
        required: true
        default: 'blocked'

# https://docs.github.com/en/actions/security-guides/automatic-token-authentication#permissions-for-the-github_token
permissions:
  contents: write
  pull-requests: write
  actions: write

# A workflow run is made up of one or more jobs that can run sequentially or in parallel
jobs:
  # This workflow contains a single job called "combine-prs"
  combine-prs:
    # The type of runner that the job will run on
    runs-on: ubuntu-latest

    # Steps represent a sequence of tasks that will be executed as part of the job
    steps:
      - uses: actions/github-script@v6
        id: fetch-branch-names
        name: Fetch branch names
        # Use GitHub's GraphQL API to minimize API calls.
        with:
          github-token: ${{secrets.GITHUB_TOKEN}}
          script: |
            // Construct the search to return the PRs that match our conditions.
            const searchString = `repo:${context.repo.owner}/${context.repo.repo} is:pr is:open label:dependencies label:python -label:${{ github.event.inputs.ignoreLabel }}`;
            console.log('Search string: ' + searchString);
            // We pick the first 100 results, which should be enough for most
            // cases, and prevents the API calls from being too large (slow). 
            const matchingPullRequestQuery = `query {
              search(
                query: "${searchString}",
                type: ISSUE,
                first: 100
              ) {
                edges {
                  node {
                    ... on PullRequest {
                      number
                      title
                      headRefOid
                      mergeable
                      commits(last: 1) {
                        nodes {
                          commit {
                            statusCheckRollup {
                              state
                            }
                          }
                        }
                      }
                    }
                  }
                }
              }
            }`;
            // console.debug('Query: ' + matchingPullRequestQuery);
            // Run the query and get the results.
            const matchingPullRequests = await github.graphql(matchingPullRequestQuery);
            // log the results
            // console.debug('Matching PRs: ' + JSON.stringify(matchingPullRequests));
            // Get the PRs from the results.
            const pullRequests = matchingPullRequests.search.edges;
            // console.debug('PRs: ' + JSON.stringify(pullRequests));
            // Create an array to hold the branch names.
            let branches = [];
            // Create an array to hold the PRs.
            let prs = [];
            // Create a variable to hold the base branch.
            let baseBranch = null;
            // Sort the PRs by number, since the API response is tricky.
            pullRequests.sort((a, b) => a.node.number - b.node.number);
            // Loop through the PRs.
            for (const pull of pullRequests) {
              const prLogString = 'Pull #' + pull.node.number + ' - ' + pull.node.title;
              console.log('👀 Checking:  ' + prLogString);
              // If the PR is not mergeable (no conflicts), bail early.
              if(pull.node.mergeable != 'MERGEABLE') {
                console.warn('❌ Discarding: ' + prLogString + ' with unmergeable PR, state: ' + pull.node.mergeable);
                continue;
              }
              // If the PR is not green, bail early.
              if(${{ github.event.inputs.mustBeGreen }}) {
                if(pull.node.commits.nodes[0].commit.statusCheckRollup.state != 'SUCCESS') {
                  console.warn('❌ PR Status: ' + prLogString + ' with failed status: ' + pull.node.commits.nodes[0].commit.statusCheckRollup.state);
                  continue;
                }
                console.log('✅ PR Status: ' + prLogString);
              }
              // At this point, the PR/branch is good to go.
              const branch = pull.node.headRefOid;
              console.log('☑️ Adding branch to array: ' + branch);
              // Add the branch name to the array.
              branches.push(branch);
              // Add the PR to the array.
              prs.push('Closes #' + pull.node.number + ' ' + pull.node.title);
              baseBranch = pull.node.headRefOid;
            }

            if (branches.length == 0) {
              core.setFailed('No PRs/branches matched criteria');
              return;
            }

            core.setOutput('base-branch', baseBranch);
            core.setOutput('prs-string', prs.join('\n'));

            combined = branches.join(' ')
            console.log('Combined: ' + combined);
            return combined
      # Checks-out your repository under $GITHUB_WORKSPACE, so your job can access it
      - uses: actions/checkout@v3
        with:
          fetch-depth: 0
      # Creates a branch with other PR branches merged together
      - name: Created combined branch
        env:
          BASE_BRANCH: ${{ steps.fetch-branch-names.outputs.base-branch }}
          BRANCHES_TO_COMBINE: ${{ steps.fetch-branch-names.outputs.result }}
          COMBINE_BRANCH_NAME: ${{ github.event.inputs.combineBranchName }}
        run: |
          sourcebranches="${BRANCHES_TO_COMBINE%\"}"
          sourcebranches="${sourcebranches#\"}"

          basebranch="${BASE_BRANCH%\"}"
          basebranch="${basebranch#\"}"

          git config pull.rebase false
          git config user.name github-actions
          git config user.email github-actions@github.com

          git branch $COMBINE_BRANCH_NAME $basebranch
          git checkout $COMBINE_BRANCH_NAME
          git pull origin $sourcebranches --no-edit
          git push origin $COMBINE_BRANCH_NAME
      # Creates a PR with the new combined branch
      - uses: actions/github-script@v6
        name: Create Combined Pull Request
        with:
          github-token: ${{secrets.GITHUB_TOKEN}}
          script: |
            const prString = `${{ steps.fetch-branch-names.outputs.prs-string }}`;
            const body = 'This PR was created by the Combine PRs action by combining the following PRs:\n\n' + prString;
            await github.rest.pulls.create({
              owner: context.repo.owner,
              repo: context.repo.repo,
              title: 'Combined PR',
              head: '${{ github.event.inputs.combineBranchName }}',
              base: 'main',
              body: body
            });
      # Trigger downstream workflows
      # https://github.blog/changelog/2022-09-08-github-actions-use-github_token-with-workflow_dispatch-and-repository_dispatch/
      - uses: actions/github-script@v6
        name: Trigger CI
        with:
          github-token: ${{secrets.GITHUB_TOKEN}}
          script: |
            for (const workflow_id of ['ci.yml', 'node-ci.yml']) {
              await github.rest.actions.createWorkflowDispatch({
                owner: context.repo.owner,
                repo: context.repo.repo,
                workflow_id: workflow_id,
                ref: '${{ github.event.inputs.combineBranchName }}'
              });
            }