Preview watchdog #315
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| name: Preview watchdog | |
| # Catches PR previews whose "Backend target: preview requested" comment is | |
| # stuck because a `backend_preview_ready` or `backend_preview_failed` | |
| # dispatch was lost (token expired, GitHub API blip, job crashed, etc.). | |
| # Today this leaves the author staring at a stale "preview requested" | |
| # message with no recourse. Watchdog runs every 15 minutes and nudges | |
| # anything older than 20 minutes with a follow-up comment and link to | |
| # re-run the upsert-preview workflow. | |
| # | |
| # Strictly additive — doesn't modify existing preview comments, only adds | |
| # a sibling `mcpjam-preview-watchdog` comment. Posts once per stuck PR and | |
| # keeps the comment updated, so it won't spam the PR thread. | |
| on: | |
| schedule: | |
| - cron: "*/15 * * * *" | |
| workflow_dispatch: {} | |
| permissions: | |
| contents: read | |
| pull-requests: write | |
| jobs: | |
| scan-stuck-previews: | |
| runs-on: ubuntu-latest | |
| steps: | |
| - uses: actions/github-script@v7 | |
| with: | |
| script: | | |
| const previewMarker = "<!-- mcpjam-preview -->"; | |
| const watchdogMarker = "<!-- mcpjam-preview-watchdog -->"; | |
| const stuckAfterMs = 20 * 60 * 1000; | |
| const prs = await github.paginate(github.rest.pulls.list, { | |
| owner: context.repo.owner, | |
| repo: context.repo.repo, | |
| state: "open", | |
| per_page: 100, | |
| }); | |
| for (const pr of prs) { | |
| const comments = await github.paginate(github.rest.issues.listComments, { | |
| owner: context.repo.owner, | |
| repo: context.repo.repo, | |
| issue_number: pr.number, | |
| per_page: 100, | |
| }); | |
| const previewComment = comments.find((c) => | |
| c.body?.includes(previewMarker), | |
| ); | |
| if (!previewComment) continue; | |
| // Only nudge when the current state is "preview requested" | |
| // — that's the specific stuck-waiting state we can resolve. | |
| if (!previewComment.body?.includes("Backend target: preview requested")) { | |
| continue; | |
| } | |
| const updatedAt = new Date(previewComment.updated_at).getTime(); | |
| if (Date.now() - updatedAt < stuckAfterMs) continue; | |
| const ageMinutes = Math.round( | |
| (Date.now() - updatedAt) / 60000, | |
| ); | |
| const runsUrl = `https://github.com/${context.repo.owner}/${context.repo.repo}/actions/workflows/pr-preview.yml?query=branch%3A${encodeURIComponent(pr.head.ref)}`; | |
| const body = [ | |
| watchdogMarker, | |
| "### Preview watchdog", | |
| `The "preview requested" state has been stuck for ~${ageMinutes} minutes.`, | |
| "The backend callback probably dropped (token expired, dispatch failed, or the backend job crashed).", | |
| "", | |
| `Recover: re-run the [\`upsert-preview\` workflow](${runsUrl}) for this PR, or push an empty commit.`, | |
| "", | |
| "_Watchdog runs every 15 minutes; this comment updates in place when conditions change._", | |
| ].join("\n"); | |
| const existing = comments.find((c) => | |
| c.body?.includes(watchdogMarker), | |
| ); | |
| if (existing) { | |
| if (existing.body === body) continue; | |
| await github.rest.issues.updateComment({ | |
| owner: context.repo.owner, | |
| repo: context.repo.repo, | |
| comment_id: existing.id, | |
| body, | |
| }); | |
| continue; | |
| } | |
| await github.rest.issues.createComment({ | |
| owner: context.repo.owner, | |
| repo: context.repo.repo, | |
| issue_number: pr.number, | |
| body, | |
| }); | |
| } |