subreaper

Subreaper

Run gopherd as a supervisor when it is not PID 1, and have the kernel notify children if gopherd dies abruptly.

Config

# Subreaper mode for non-PID-1 deployments, plus parent-death cleanup.
subreaper: true
processes:
  - name: app
    command: /usr/local/bin/app
    args: ["300"]
    parent-death-signal: SIGTERM
    on-failure: shutdown

• subreaper: true — sets PR_SET_CHILD_SUBREAPER so orphaned descendants re-parent to gopherd instead of host PID 1, letting its reap loop collect them. Use when gopherd is not PID 1 (e.g. docker exec, a k8s sidecar, or nested init). Linux-only.
• parent-death-signal: SIGTERM — sets PR_SET_PDEATHSIG; the kernel delivers this signal to app if gopherd dies, so the child shuts down rather than being orphaned. Linux-only.

Expected behavior

• Orphaned grandchildren of app re-parent to gopherd and get reaped, avoiding zombies.
• If gopherd is killed, app receives SIGTERM from the kernel and exits.

Test

ValidateParse level — behavior is environment-dependent (cgroup limits / remote syslog / file rotation thresholds), so the test asserts the config loads and validates. Subreaper and parent-death-signal are Linux runtime behaviors; parse-validate is the honest CI-portable level.

go test ./documentation/subreaper/ -v