fix(supervisor): restart haproxy in-place if it dies while container lives

haproxy runs as a background child of PID 1 (gunicorn) with nothing
watching it after init. If the haproxy master dies mid-life (observed
2026-07-01 on whp01: SIGABRT -> exit 134, reaped by gunicorn and logged
as "Worker (pid:22) exited"), the container stays "up", Docker's
--restart never fires, and haproxy is down until the external host
watchdog full-restarts the whole container minutes later (dropping every
connection).

Add an in-container supervisor loop in start-up.sh (Phase 1.5) that runs
scripts/ensure_haproxy.py every HAPROXY_SUPERVISOR_INTERVAL (default 15s).
ensure_haproxy.py calls the existing, idempotent start_haproxy() only when
haproxy isn't running (psutil guard), reviving it in place within one
interval with no container restart. Same entrypoint-supervision pattern
shipped for cac-litespeed.

Validated locally: killing haproxy -> revived with new PIDs in ~one
interval, container stayed healthy, no spurious restarts while healthy.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

VERSION

@@ -1 +1 @@
-2026.06.3
+2026.07.1

scripts/ensure_haproxy.py

@@ -0,0 +1,52 @@
+#!/usr/bin/env python3
+"""Idempotent haproxy liveness check — driven by the in-container supervisor loop.
+
+Why this exists
+---------------
+haproxy runs as a *background child of PID 1* (gunicorn) — it is started once at
+container init (scripts/init.py -> do_initial_setup -> start_haproxy) and then
+left running. Nothing supervises it after that. If the haproxy master process
+dies mid-life (SIGABRT -> exit 134, segfault, or an OOM of the haproxy master),
+the container stays "up" because gunicorn is still PID 1, so Docker's
+`--restart` policy never fires. haproxy then stays down until the *external*
+host watchdog (haproxy-watchdog.sh) notices port 80 is dead for ~3 minutes and
+does a full `docker restart` — which drops every in-flight connection.
+
+This script closes that gap: called on a short interval by the supervisor loop
+in start-up.sh, it re-launches haproxy *in place* within one interval.
+
+Safety
+------
+start_haproxy() is guarded by `is_process_running('haproxy')` (psutil-based, so
+it works in this container which has no `ps`), so calling this while haproxy is
+healthy is a cheap no-op. It only ever acts when haproxy is genuinely gone.
+"""
+import sys
+
+sys.path.insert(0, '/haproxy')
+import haproxy_manager  # noqa: E402  (sys.path manipulation must come first)
+
+
+def main():
+    if haproxy_manager.is_process_running('haproxy'):
+        return 0
+
+    haproxy_manager.logger.warning(
+        "[haproxy-supervisor] haproxy process not found — attempting in-place restart"
+    )
+    # start_haproxy() validates the config (and regenerates it if invalid)
+    # before launching, and swallows its own errors, so it will not raise here.
+    haproxy_manager.start_haproxy()
+
+    if haproxy_manager.is_process_running('haproxy'):
+        haproxy_manager.logger.info("[haproxy-supervisor] haproxy restarted in place")
+        return 0
+
+    haproxy_manager.logger.error(
+        "[haproxy-supervisor] haproxy restart FAILED — still not running after start_haproxy()"
+    )
+    return 1
+
+
+if __name__ == '__main__':
+    sys.exit(main())

scripts/start-up.sh

@@ -27,6 +27,22 @@ cron &
 # Phase 1: container init
 python /haproxy/scripts/init.py
 
+# Phase 1.5: in-container haproxy supervisor.
+# haproxy runs as a background child of PID 1 (gunicorn) with NOTHING watching
+# it after init. If the haproxy master dies mid-life (e.g. SIGABRT -> exit 134,
+# segfault), the container stays "up" (gunicorn is PID 1), Docker's --restart
+# policy never fires, and haproxy is down until the external host watchdog
+# full-restarts the whole container minutes later (dropping every connection).
+# This loop revives haproxy in place within one interval. ensure_haproxy.py is
+# idempotent — a cheap no-op whenever haproxy is already running.
+HAPROXY_SUPERVISOR_INTERVAL="${HAPROXY_SUPERVISOR_INTERVAL:-15}"
+(
+    while true; do
+        sleep "${HAPROXY_SUPERVISOR_INTERVAL}"
+        python /haproxy/scripts/ensure_haproxy.py 2>&1 || true
+    done
+) &
+
 # Phase 2: WSGI servers
 # Tunable via env: HAPROXY_MGR_API_WORKERS (default 1), HAPROXY_MGR_API_TIMEOUT
 # (default 120 — API can do slow ACME calls), HAPROXY_MGR_MAX_REQUESTS (default