pr_template_check.yml

name: PR template check

# This check flags external pull requests that do not use the pull request template, and
# closes them if the template is still missing after a grace period.
#
# pull_request_target is required so the token can label, comment on, and close
# pull requests opened from forks. This is safe only because the workflow never
# checks out or runs code from the pull request; it reads the PR body via the
# event payload. Do not add an actions/checkout step to this workflow.
on: # zizmor: ignore[dangerous-triggers] PR code is never checked out or executed
  pull_request_target:
    types:
      - opened
      - edited
      - reopened
      - ready_for_review
      - converted_to_draft
  schedule:
    - cron: "0 18 * * *" # 1 PM EST
  workflow_dispatch:

permissions: {}

env:
  LABEL: needs-template
  GRACE_DAYS: "3"
  MARKER: "<!-- pr-template-check -->"

jobs:
  check:
    if: >-
      github.event_name == 'pull_request_target' &&
      github.event.pull_request.user.type != 'Bot' &&
      !contains(fromJSON('["OWNER", "MEMBER"]'), github.event.pull_request.author_association)
    runs-on: ubuntu-latest
    permissions:
      issues: write # Labels and comments on PRs use the issues API.
      pull-requests: write
    concurrency:
      group: ${{ github.workflow }}-${{ github.event.pull_request.number }}
      cancel-in-progress: true
    steps:
      - name: Check PR body against template
        uses: actions/github-script@3a2844b7e9c422d3c10d287c895573f7108da1b3 # v9.0.0
        with:
          script: |
            const { LABEL, GRACE_DAYS, MARKER } = process.env;
            const pr = context.payload.pull_request;
            const issue = { ...context.repo, issue_number: pr.number };

            // Remove HTML comments so untouched template placeholders don't count as content.
            const body = (pr.body || '').replace(/<!--[\s\S]*?-->/g, '');

            // Only the parts above the template's "You can erase any parts of this template"
            // note are required. These must match .github/PULL_REQUEST_TEMPLATE.md.
            const problems = [];

            // The change summary runs until the "All Submissions:" checklist or the next heading.
            const summary = body.match(/^###\s+Change summary\s*$([\s\S]*?)(?=^\s*All Submissions:|^###|(?![\s\S]))/mi);
            if (!summary) {
              problems.push('the `### Change summary` section is missing');
            } else if (summary[1].trim() === '') {
              problems.push('the `### Change summary` section is empty');
            }

            if (!/^\s*All Submissions:\s*$/mi.test(body)) {
              problems.push('the `All Submissions:` checklist is missing');
            }

            const { data: comments } = await github.rest.issues.listComments({ ...issue, per_page: 100 });
            const existing = comments.find((c) => c.user.type === 'Bot' && c.body.includes(MARKER));

            // Drafts are not checked. Clearing the label means the grace period starts
            // fresh when the pull request is marked ready for review.
            if (problems.length === 0 || pr.draft) {
              await github.rest.issues.removeLabel({ ...issue, name: LABEL }).catch((e) => {
                if (e.status !== 404) throw e;
              });
              if (existing) {
                await github.rest.issues.deleteComment({ ...context.repo, comment_id: existing.id });
              }
              return;
            }

            const templateUrl = `https://github.com/${context.repo.owner}/${context.repo.repo}/blob/${pr.base.ref}/.github/PULL_REQUEST_TEMPLATE.md`;
            const message = [
              MARKER,
              `Thanks for the contribution! This pull request doesn't follow our [pull request template](${templateUrl}):`,
              '',
              ...problems.map((p) => `- ${p}`),
              '',
              `Please edit the description to use the template. If it is still missing after ${GRACE_DAYS} days, this pull request will be closed automatically.`,
            ].join('\n');

            await github.rest.issues.addLabels({ ...issue, labels: [LABEL] });
            if (existing) {
              await github.rest.issues.updateComment({ ...context.repo, comment_id: existing.id, body: message });
            } else {
              await github.rest.issues.createComment({ ...issue, body: message });
            }

  close:
    if: github.event_name == 'schedule' || github.event_name == 'workflow_dispatch'
    runs-on: ubuntu-latest
    permissions:
      issues: write # Comments on PRs use the issues API.
      pull-requests: write
    steps:
      - name: Close PRs still missing the template
        uses: actions/github-script@3a2844b7e9c422d3c10d287c895573f7108da1b3 # v9.0.0
        with:
          script: |
            const { LABEL, GRACE_DAYS } = process.env;
            const cutoff = Date.now() - Number(GRACE_DAYS) * 24 * 60 * 60 * 1000;

            const prs = await github.paginate(github.rest.pulls.list, {
              ...context.repo,
              state: 'open',
              per_page: 100,
            });

            for (const pr of prs.filter((p) => !p.draft && p.labels.some((l) => l.name === LABEL))) {
              const issue = { ...context.repo, issue_number: pr.number };
              const events = await github.paginate(github.rest.issues.listEvents, { ...issue, per_page: 100 });
              const labeled = events.filter((e) => e.event === 'labeled' && e.label?.name === LABEL).pop();
              if (!labeled || new Date(labeled.created_at).getTime() > cutoff) {
                continue;
              }

              core.info(`Closing #${pr.number}: labeled ${LABEL} at ${labeled.created_at}`);
              await github.rest.issues.createComment({
                ...issue,
                body: `Closing because the pull request template is still missing after ${GRACE_DAYS} days. Feel free to open a new pull request that uses the template.`,
              });
              await github.rest.pulls.update({ ...context.repo, pull_number: pr.number, state: 'closed' });
            }