Files
openclaw/docs/gateway/gateway-lock.md
Vincent Koc 637f15375b docs: fix Gateway & Ops audit findings (7 pages)
- cli-backends.md: remove duplicate modelAliases key
- discovery.md: add missing transport=gateway and displayName TXT keys
- authentication.md: retitle to "Authentication (Model Providers)", add
  disambiguation Note pointing to gateway connection auth docs
- health.md: expand frontmatter scope, add --probe flag and response shape docs
- gateway-lock.md: remove stale hardcoded date, add Related section
- troubleshooting.md: fix wrong auth cross-link (model auth -> gateway config)
- logging.md: add Related section linking to gateway logging internals
2026-03-31 14:24:19 +09:00

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Markdown

---
summary: "Gateway singleton guard using the WebSocket listener bind"
read_when:
- Running or debugging the gateway process
- Investigating single-instance enforcement
title: "Gateway Lock"
---
# Gateway lock
## Why
- Ensure only one gateway instance runs per base port on the same host; additional gateways must use isolated profiles and unique ports.
- Survive crashes/SIGKILL without leaving stale lock files.
- Fail fast with a clear error when the control port is already occupied.
## Mechanism
- The gateway binds the WebSocket listener (default `ws://127.0.0.1:18789`) immediately on startup using an exclusive TCP listener.
- If the bind fails with `EADDRINUSE`, startup throws `GatewayLockError("another gateway instance is already listening on ws://127.0.0.1:<port>")`.
- The OS releases the listener automatically on any process exit, including crashes and SIGKILL—no separate lock file or cleanup step is needed.
- On shutdown the gateway closes the WebSocket server and underlying HTTP server to free the port promptly.
## Error surface
- If another process holds the port, startup throws `GatewayLockError("another gateway instance is already listening on ws://127.0.0.1:<port>")`.
- Other bind failures surface as `GatewayLockError("failed to bind gateway socket on ws://127.0.0.1:<port>: …")`.
## Operational notes
- If the port is occupied by _another_ process, the error is the same; free the port or choose another with `openclaw gateway --port <port>`.
- The macOS app still maintains its own lightweight PID guard before spawning the gateway; the runtime lock is enforced by the WebSocket bind.
## Related
- [Multiple Gateways](/gateway/multiple-gateways) — running multiple instances with unique ports
- [Troubleshooting](/gateway/troubleshooting) — diagnosing `EADDRINUSE` and port conflicts