Files
selfpost/build/crashexit.py
T
mixandClaude Opus 5.5 599149bf83 build, deploy, inbound, dmarc, backup, e2e: cite the source of what they rely on (assumptions part C)
Comments only, no behaviour changed. Each main.cf/master.cf parameter the
build sets, the wrapper's and the reload hook's reliance on Postfix 3.7.11
(postfix-script, master.5, postconf.5, cleanup_init.c, smtpd_peer.c,
README_FILES), supervisor 4.2.5 (process.py, options.py, events.rst),
logrotate 3.21.0, OpenDKIM's config, Cyrus SASL's sasldb, rspamd 3.11.1
(milter_headers.lua, multimap, the map watcher), Docker Compose, CoreDNS
and certbot now say where that is written. Measurements already there stay
measurements ("date not recorded" where none was); hand-composed fixtures
say so.

Contradictions left for their own commits: C-P31 cleanup's size limit,
C-P42 master outside supervisor's signal, C-V5/V6 startsecs, C-V10,
C-S3/Q3 sasldb written in place, C-Q4/A1 certbot's symlinks, C-R7 rspamd
skips local clients but the signature routine does not, C-P8, C-R4, C-R12,
C-M7, C-E2, C-K8/K9, C-D1.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
2026-10-14 19:39:21 +03:00

54 lines
1.8 KiB
Python

#!/usr/bin/env python3
"""Supervisor event listener: bring the container down on unrecoverable failure.
If any managed program exhausts its restart retries and enters FATAL, this
listener signals supervisord (its parent) to terminate, so the whole container
exits and Docker's `restart` policy can recreate it cleanly — rather than
lingering "alive" with a dead Postfix/OpenDKIM/panel.
Communication with supervisord uses the event listener protocol over stdin and
stdout, so stdout must carry only protocol tokens.
supervisor 4.2.5, docs/events.rst, "Event Listener Notification Protocol": the
listener writes READY\\n, reads one header line of key:value tokens whose len
is the payload's length, reads the payload, and answers "RESULT 2\\nOK".
supervisord starts the listener as its own child, and on SIGTERM it shuts down
(docs/running.rst, "Signals"); it is PID 1 here (build/entrypoint.sh, exec).
"""
import os
import signal
import sys
def write_stdout(s):
sys.stdout.write(s)
sys.stdout.flush()
def main():
while True:
# Tell supervisord we are ready for the next event.
write_stdout("READY\n")
line = sys.stdin.readline()
if not line:
return
headers = dict(pair.split(":", 1) for pair in line.split())
payload_len = int(headers.get("len", 0))
if payload_len:
sys.stdin.read(payload_len)
# We only subscribe to PROCESS_STATE_FATAL, so any event means a managed
# program can no longer be restarted. Take the container down.
sys.stderr.write(
"crashexit: a managed process entered FATAL; shutting down container\n"
)
sys.stderr.flush()
os.kill(os.getppid(), signal.SIGTERM)
write_stdout("RESULT 2\nOK")
if __name__ == "__main__":
main()