fix(api): bound all subprocess calls + run 2 workers to prevent API stall

The management API wedged on whp01 2026-07-07: every panel call to the
manager (config regenerate during a WHP site update, SSL, even /health)
timed out at 30s while customer sites stayed up. Root cause: all four
gunicorn gthread worker threads were permanently blocked in socket reads
inside untimed subprocess.run() calls (certbot ACME / socat reloads). A
stalled external command holds its worker thread forever; gunicorn
--timeout can't rescue it (gthread only kills a worker whose main thread
stops heart-beating, and ours kept polling). Stalled calls accumulated
until the 4-thread pool was exhausted and the whole API went dark.

- Wrap subprocess.run with a default timeout (HAPROXY_MGR_SUBPROCESS_TIMEOUT,
  180s) so every external command is bounded and releases its thread on
  expiry via the existing per-endpoint try/except. Bounding by default
  covers all ~30 call sites and any future one.
- certbot renew keeps an explicit 900s timeout (walks every lineage).
- API_WORKERS default 1 -> 2: a single worker made a thread-pool wedge a
  total outage; a second worker keeps the API answering while one recycles.

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

haproxy_manager.py

@@ -18,6 +18,38 @@ import time
 import re
 import fcntl
 
+# ---------------------------------------------------------------------------
+# Bounded subprocess execution (incident 2026-07-07)
+# ---------------------------------------------------------------------------
+# Every external command this manager runs — certbot ACME issuance/renewal,
+# `socat` reloads over the haproxy admin socket, `haproxy -c` validation — is a
+# potential hang. The management API runs under gunicorn gthread workers, and a
+# subprocess.run() with NO timeout blocks its worker thread forever if the
+# command stalls (e.g. an ACME/upstream that stops responding mid-read).
+# gunicorn's --timeout does not rescue this: for gthread it only kills a worker
+# whose *main* thread stops heart-beating, but the main thread keeps polling
+# while pool threads are wedged. Enough stalled calls exhaust the 4-thread pool
+# and the whole API stops responding — "healthy" health-check, every request
+# 30s-timeouts — which is exactly what stalled WHP site updates on 2026-07-07.
+#
+# Fix: give EVERY subprocess.run() a default timeout unless the caller passes
+# one explicitly. On expiry Python kills the child and raises
+# subprocess.TimeoutExpired (a subclass of Exception); the existing per-endpoint
+# try/except turns that into a clean error AND releases the worker thread.
+# Bounding by default (instead of editing ~30 call sites) means no site can be
+# missed and any future call is protected automatically.
+DEFAULT_SUBPROCESS_TIMEOUT = int(os.environ.get('HAPROXY_MGR_SUBPROCESS_TIMEOUT', '180'))
+_unbounded_subprocess_run = subprocess.run
+
+
+def _bounded_subprocess_run(*args, **kwargs):
+    if kwargs.get('timeout') is None:
+        kwargs['timeout'] = DEFAULT_SUBPROCESS_TIMEOUT
+    return _unbounded_subprocess_run(*args, **kwargs)
+
+
+subprocess.run = _bounded_subprocess_run
+
 app = Flask(__name__)
 
 # Default page server (port 8080) — served to HAProxy clients whose request hit
@@ -811,10 +843,12 @@ def renew_certificates():
         # Defensive: clear any stale lock left by a SIGKILLed prior run.
         clear_stale_certbot_locks()
 
-        # Run certbot renew
+        # Run certbot renew. Explicit long timeout (overrides the module
+        # default): `renew` walks every lineage and can legitimately make many
+        # ACME round-trips when several certs are actually due.
         result = subprocess.run([
             'certbot', 'renew', '--quiet'
-        ], capture_output=True, text=True)
+        ], capture_output=True, text=True, timeout=900)
         
         if result.returncode == 0:
             # Check if any certificates were renewed