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: ```bash --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. ```bash bazel build //:nativelink bazel test //nativelink-store/... bazel test //nativelink-scheduler/... bazel test //nativelink-worker/... bazel test //nativelink-service/... ``` For full confidence: ```bash 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.