Propagate Distributed Trace Context Across Hops
Inject the traceparent header on every outbound call so a request is traceable across service boundaries.
Task
Instrument fetch(url, { headers: { traceparent: ctx.traceparent } }) so on-call engineers can diagnose an incident without guessing at log lines.
When to use this
An outage lasts 47 minutes because the team cannot correlate fetch(url, { headers: { traceparent: ctx.traceparent } }) across services without structured traces.
Prerequisites
- An application with structured logging available
- A metrics or tracing backend configured
Steps
1. Configure fetch(url, { headers: { traceparent: ctx.traceparent } }) in the project configuration file with the recommended defaults.
fetch(url, { headers: { traceparent: ctx.traceparent } })
Expected output: The configuration is accepted and fetch(url, { headers: { traceparent: ctx.traceparent } }) runs without errors on the first invocation.
2. Run the check locally to verify fetch(url, { headers: { traceparent: ctx.traceparent } }) 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 fetch(url, { headers: { traceparent: ctx.traceparent } }) blocks merge on failure.
- name: Run add distributed trace context
run: pnpm test
Expected output: Pull requests with failing fetch(url, { headers: { traceparent: ctx.traceparent } }) 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.
Make the system observable
Start by measuring the problem. Inject the traceparent header on every outbound call so a request is traceable across service boundaries. The most common mistake is adding the gate without first confirming it catches the issue you care about. Run fetch(url, { headers: { traceparent: ctx.traceparent } }) against the current codebase and inspect the output before wiring it into CI.
fetch(url, { headers: { traceparent: ctx.traceparent } })Correlate across services
Once the gate is in place, make failures actionable. A failing fetch(url, { headers: { traceparent: ctx.traceparent } }) 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.