signal-rewrite

Signal rewrite

Signal forwarding is strict opt-in. A service receives a signal sent to gopherd only if its per-process signal-rewrite map lists that signal; the value names the signal actually delivered to the child. Unmapped signals (e.g. SIGUSR2 with no entry) are dropped.

Config

processes:
  - name: app
    command: /bin/sh
    args: ["-c", "trap 'exit 0' TERM; while true; do sleep 0.2; done"]
    on-success: ignore
    on-failure: ignore
    signal-rewrite:
      USR1: TERM

• signal-rewrite: {USR1: TERM} — a SIGUSR1 received by gopherd is delivered to app as SIGTERM. Keys and values are signal names; both USR1 and SIGUSR1 forms are accepted.
• Keys may not be SIGHUP (reserved for reload) or any signal in init-stop-signal (consumed by gopherd for its own shutdown). Such configs are rejected at load.
• on-success: ignore / on-failure: ignore — when app exits, gopherd does not shut down; it stays alive as a supervisor.

Expected behavior

• app traps SIGTERM and exits 0 when it arrives.
• Sending SIGUSR1 to gopherd is rewritten to SIGTERM, so app exits.
• The ignore exit actions keep gopherd running afterward.

Test

The test asserts status app is running, sends SIGUSR1 to the daemon, then polls until status app is no longer running (proving the rewritten SIGTERM reached the service). It then asserts the daemon is still Alive() and SIGTERM cleanly shuts it down with exit 0. Verified stable across repeated runs.

go test ./documentation/signal-rewrite/ -v