Setup
Taskcluster CLI: Assume taskcluster is already installed and on PATH — do not verify this up front. Only if a command fails with a "not found"/"command not found" error, install it from https://github.com/taskcluster/taskcluster/releases/latest/ and retry.
export TASKCLUSTER_ROOT_URL=https://firefox-ci-tc.services.mozilla.com
Commands:
taskcluster task log <task-id>- Get logstaskcluster task def <task-id>- Get definition (optional)
Debug Process
- Extract task ID from message or URL
- Fetch logs:
taskcluster task log <task-id> - Analyze errors (tracebacks, test failures, build errors)
- If fix is obvious → apply it. Otherwise → reproduce locally:
- Docker-worker tasks:
taskgraph load-task --develop <task-id>(Firefox:./mach taskgraph, others: check virtualenv oruv run taskgraph) - Flags:
--interactive,--volume,--root,--image,--keep - Non-docker: extract command from task def and run locally
- Docker-worker tasks:
- For non-obvious issues: add debug statements → iterate → fix
- Verify fix using same reproduction method
- Clean up debug artifacts (don't re-verify after cleanup)
- Report: root cause, fix, verification, files changed