Nativelink Lre Debug

NativeLink Local Remote Execution Debugging

Use this skill when NativeLink is acting as a remote cache, remote executor, local remote execution server, or BEP target and something is missing, slow, or failing.

Identify The Mode

Start by recording the exact Bazel command and which NativeLink mode is involved:

• Remote cache self-test: --config=self_test, usually grpc://127.0.0.1:50051.
• Remote executor self-test: --config=self_execute, usually grpc://127.0.0.1:50052.
• Local remote execution overlays under local-remote-execution/.
• BEP ingestion or dashboard testing, which needs Build Event Protocol upload flags.

For rich action-level BEP data, include:

--build_event_publish_all_actions

This matters for helping users find build failures and slow actions faster.

First Checks

1. Confirm the NativeLink server process is running.
2. Confirm the expected ports aren't occupied by stale processes.
3. Capture NativeLink logs and the exact Bazel stdout/stderr.
4. Check whether the failure is CAS/AC storage, scheduler matching, worker execution, protocol, or client config.

Don't kill user services unless the user explicitly asks. Inspect ports and processes first.

Subsystem Map

• CAS/AC or cache misses: start in nativelink-store/.
• Worker execution failure: start in nativelink-worker/.
• Queueing, platform properties, or worker compatibility: start in nativelink-scheduler/.
• REAPI, bytestream, action cache, or BEP API behavior: start in nativelink-service/.
• Client templates and flags: start in templates/ and local-remote-execution/.

Useful Verification Commands

Inspect labels before running if unsure.

bazel build //:nativelink
bazel test //nativelink-store/...
bazel test //nativelink-scheduler/...
bazel test //nativelink-worker/...
bazel test //nativelink-service/...

For full confidence:

bazel test //...

Debug Output To Preserve

When reporting a failure, include:

• NativeLink server config path and relevant ports.
• Bazel remote cache/executor URL.
• Whether --build_event_publish_all_actions was set.
• First server-side error and first client-side error.
• The failing target label and action mnemonic, if available.