Node inspector opened and attached in api/worker without --inspect — is this a Railway feature?
niyexdroid
HOBBYOP

10 hours ago

Problem and desired outcome

Our production api and worker services (Node.js) log that the Node debugger has opened on 127.0.0.1:9229 and that a debugger client attached. We never enable the inspector, so we expected no such lines. Nothing is broken and the service is healthy; we want to understand what opens and attaches the debugger. It is still happening on the current deployments. We would like Railway to tell us whether a Railway platform feature (tracing, profiling, diagnostics or similar) does this, which feature it is, and what would stop working if we blocked it.

Resources and timing

  • Project: ajoquest (38d7f7c6-7278-4409-afae-f7c6bcc7f483)
  • Environment: production (7db59fba-6b53-4a6f-bdad-54682b72ff07)
  • Services: api and worker (web is a Next.js service and was not checked)
  • Builder: Railpack. api start command: pnpm start:api, which runs node -r ./apps/api/dist/tracing.js apps/api/dist/index.js

Occurrences we observed (all times UTC, from railway logs <deploymentId> --json):

  • api deployment 932fa820-586b-489c-ba4f-49157514e629: started 2026-09-25T08:00:49Z; debugger lines at 2026-09-26T10:43:48Z (about a day after start)
  • api deployment 1f74dd49-fef9-4baa-b01f-4191e6ec188a (2026-09-28): one occurrence (timestamp not pulled)
  • api deployment 8ab65e75-d8d0-411c-addb-e6e314573605 (currently running): started 2026-10-01T05:28:14Z; debugger lines at 2026-10-01T05:28:44Z (30 seconds after start)
  • worker deployment 1dc4a860-6f9c-481e-891f-32863f04facd (currently running): same three lines seen

Deployments with no occurrence in the last 200 log lines: api bd04fb29-e26c-471b-9387-c16f7ec74144 (2026-09-30) and bc727b9d-02a1-4daf-8784-7c5c30c0fa14 (2026-09-23).

Note: a newer api/worker deployment from commit 933a7b9 (pushed 2026-10-01 around 08:33 UTC) may now be the running one; its logs have not been checked.

Evidence and attempts

Log excerpt, api deployment 8ab65e75-d8d0-411c-addb-e6e314573605:

2026-10-01T05:28:14.866Z  AjoQuest API listening on :8080
2026-10-01T05:28:44.854Z  Debugger listening on ws://127.0.0.1:9229/4ac56323-b6ca-4cba-9052-391e5ca3f3e9
2026-10-01T05:28:44.854Z  For help, see: https://nodejs.org/learn/getting-started/debugging
2026-10-01T05:28:44.854Z  Debugger attached.

Worker deployment 1dc4a860-6f9c-481e-891f-32863f04facd shows the same pattern (Debugger listening on ws://127.0.0.1:9229/dbd265f2-9bb1-4c1c-9474-f83739b729e2, then Debugger attached.).

Checks performed:

  • Our repository contains no --inspect flag. The api service variables contain no NODE_OPTIONS or inspect-related variable.
  • Using railway ssh into the api container: NODE_OPTIONS is empty, and the process list shows only pnpm start:api, sh -c node -r ./apps/api/dist/tracing.js apps/api/dist/index.js and node ... (plus our ssh shell). No --inspect on the command line. The container has OTEL_EXPORTER_OTLP_* and OTEL_SERVICE_* variables, which we did not set ourselves.
  • We searched all installed npm packages for code that calls inspector.open. The only matches used by the api are in @sentry/node 11.1.0 (LocalVariables and ANR integrations). Neither is active: LocalVariables only starts when includeLocalVariables: true (we don't set it), and we don't use ANR. The lines also appear on 2026-09-25/26, before we added Sentry on 2026-09-30.
  • Starting the same built api locally with a hook on inspector.open and production-like environment variables: the debugger never opened.
  • We deployed a change that removed Sentry's LocalVariables integration (commit b39ed1b). The lines still appeared on the new deployments (8ab65e75 and 1dc4a860), so we reverted it (commit 933a7b9).
$10 Bounty

1 Replies

Railway
BOT

10 hours ago

This thread has been opened as a bounty so the community can help solve it.

Status changed to Open Railway • about 10 hours ago

kk-agent
FREETop 5% Contributor

5 hours ago

Hey — those lines are Node’s inspector, not a Railway-documented tracing/profiling product. Here’s what published docs support vs leave open.

How Node opens / attaches

Node listens for a debugger when started with --inspect (default 127.0.0.1:9229), when it gets SIGUSR1 (unless --disable-sigusr1), or when inspect flags arrive via NODE_OPTIONS (Debugging Node.js, CLI --inspect / NODE_OPTIONS). Your logs match that default: Debugger listening on ws://127.0.0.1:9229/… then Debugger attached. — attached means a client connected to that local inspector WebSocket.

No --inspect on the argv from SSH does not rule out SIGUSR1, a transient NODE_OPTIONS, or code/-r preload calling the inspector API.

Intentional debug on Railway

To reach a non-HTTP debug port from outside the container, the published path is TCP Proxy (Settings → Networking → TCP Proxy to the internal port) (TCP Proxy, CLI tcp-proxy). That is opt-in networking — not evidence of auto-attach. Service variables can also carry Node flags such as NODE_OPTIONS (example pattern).

Undocumented (do not invent)

Railway docs do not define a platform feature that automatically opens or attaches the Node inspector. We cannot name “which Railway feature” did this, or what would break if you blocked it, from published material alone — that needs staff confirmation on your project.

Asker-side clues only

Your start uses node -r ./apps/api/dist/tracing.js …, and you saw OTEL_* vars you didn’t set. Treat those as app/deploy clues (preload/inspector.open, OTEL/Sentry injectors, anything sending SIGUSR1) — not proof of Railway auto-attach.

Next: inspect tracing.js / OTEL for inspector open, and ask Railway staff whether anything on ajoquest production api/worker injects inspect/SIGUSR1. Until documented, treat auto-attach as undocumented.

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