Trigger a Cross-Repository Pipeline on Tag

Use a repository dispatch event so tagging a shared library triggers downstream consumers to rebuild and test.

~20 mincimonorepotriggers

Task

Automate gh api -X POST /repos/$DOWNSTREAM/dispatches -f event_type=upstream-tagged -f client_payload[tag]=$TAG so pipeline failures are caught before merge and never reach production.

When to use this

A pull request merges with a broken gh api -X POST /repos/$DOWNSTREAM/dispatches -f event_type=upstream-tagged -f client_payload[tag]=$TAG step because the workflow did not gate on it, causing a failed deploy.

Prerequisites

Node.js 22 and pnpm available
A CI workflow file in .github/workflows

Steps

1. Configure gh api -X POST /repos/$DOWNSTREAM/dispatches -f event_type=upstream-tagged -f client_payload[tag]=$TAG in the project configuration file with the recommended defaults.

gh api -X POST /repos/$DOWNSTREAM/dispatches -f event_type=upstream-tagged -f client_payload[tag]=$TAG

Expected output: The configuration is accepted and gh api -X POST /repos/$DOWNSTREAM/dispatches -f event_type=upstream-tagged -f client_payload[tag]=$TAG runs without errors on the first invocation.

2. Run the check locally to verify gh api -X POST /repos/$DOWNSTREAM/dispatches -f event_type=upstream-tagged -f client_payload[tag]=$TAG produces the expected result before pushing.

pnpm test

Expected output: Local run matches CI behavior; no surprises after push.

3. Add the gate to the CI pipeline so gh api -X POST /repos/$DOWNSTREAM/dispatches -f event_type=upstream-tagged -f client_payload[tag]=$TAG blocks merge on failure.

- name: Run add cross repo pipeline trigger
  run: pnpm test

Expected output: Pull requests with failing gh api -X POST /repos/$DOWNSTREAM/dispatches -f event_type=upstream-tagged -f client_payload[tag]=$TAG are blocked from merging.

Troubleshooting

Problem

The check passes locally but fails in CI

Solution

Pin dependency versions and the runtime to match CI exactly; reproduce with the same Docker image or act.

Problem

Configuration is rejected with a schema error

Solution

Check the tool version matches the config schema; older versions may not support newer fields.

Limitations

The gate only runs on events that trigger the workflow; locally pushed commits bypass it.
Configuration drift is possible if someone edits settings outside version control.

Gate the pipeline before merge

Start by measuring the problem. Use a repository dispatch event so tagging a shared library triggers downstream consumers to rebuild and test. The most common mistake is adding the gate without first confirming it catches the issue you care about. Run gh api -X POST /repos/$DOWNSTREAM/dispatches -f event_type=upstream-tagged -f client_payload[tag]=$TAG against the current codebase and inspect the output before wiring it into CI.

gh api -X POST /repos/$DOWNSTREAM/dispatches -f event_type=upstream-tagged -f client_payload[tag]=$TAG

Make failures actionable

Once the gate is in place, make failures actionable. A failing gh api -X POST /repos/$DOWNSTREAM/dispatches -f event_type=upstream-tagged -f client_payload[tag]=$TAG should point to the exact file and line, not a generic error. Pin the tool version in the lockfile so a upstream release does not silently change behavior. Review the gate output in every pull request just like a test result.