The NS-570 epoch stamp clears a drain marker that survives a machine
restart — but it assumes every drain-gated action ends in a restart. When
a maintenance action completes WITHOUT recreating the container and the
writer never cancels the drain, the orphaned marker still carries the
current epoch, so the 1s drain watcher honours it forever and the gateway
bounces every inbound message with the 'draining for a maintenance
action' text (observed in the field: a Hermes Cloud instance refused all
Telegram turns for ~3 days).
The marker already records requested_at; now the readers check it. A
marker older than DRAIN_REQUEST_MAX_AGE_SECONDS (1h) reads as stale in
drain_requested() and drain_notification_suppressed(), with a loud
warning log. Leniency mirrors the epoch check: a missing or unparseable
timestamp still reads as drain-active (fail-safe toward quiescing), and
a legitimately long drain keeps a sanctioned keep-alive — re-calling
write_drain_request() refreshes requested_at.
Fixes#85433
Reserve API requests before their first await, include every drain-owned work type in runtime status, and pause local cron dispatch while a gateway drain is active.
Add a generic suppress_notification flag to the drain-request marker. When a
drain that ends in process exit (e.g. a NAS auto-update image migration on the
always-on Hermes Cloud fleet) is flagged, the gateway skips ONLY the
home-channel 'gateway shutting down' broadcast — the operator-flavoured ping
that would otherwise fire on every routine auto-update, dozens of times a day.
The per-active-session interrupt ping is ALWAYS kept: on a drained shutdown
it's empty by construction, and in the force-interrupt (deadline-exceeded) case
it carries the user-valuable 'your task was cut off, message me to resume' hint.
The gateway stays agnostic about WHY a drain is quiet (generic boolean, not a
kind enum); the policy of which drain causes set the flag lives in the caller
(NAS). Default-false so legacy/operator drains behave exactly as before. The
reader reuses the NS-570 epoch-staleness check so an orphaned marker on the
durable volume can never silence a fresh gateway's legitimate broadcast.
- drain_control.py: write_drain_request gains suppress_notification; new
drain_notification_suppressed() reader (current-epoch + truthy flag).
- web_server.py: /api/gateway/drain reads + echoes the flag.
- run.py: _notify_active_sessions_of_shutdown skips the home-channel loop only.
Tests prove: flag round-trips; home-channel suppressed when set, kept when
unset; active-session ping always fires; stale/legacy/corrupt markers never
suppress.
The external-drain marker .drain_request.json is written under HERMES_HOME,
which on Hermes Cloud is a persistent Fly volume (/opt/data). A begin-drain
marker therefore SURVIVES the post-update machine restart. But the disruptive
lifecycle actions a drain protects (auto-update / image migrate / env edit /
profile change) all restart the machine — which is exactly the signal the drain
is over. The freshly-restarted gateway re-read the orphaned marker on its
startup reconcile and parked itself back in 'draining', refusing every new turn
indefinitely (NS-570: ~52 min until manually cleared).
Fix: stamp the marker with an identity of THIS container/VM instantiation
(kernel boot_id + PID 1 start time, read from /proc) and treat a marker whose
epoch differs from the current instantiation as absent. A deliberate restart →
new PID 1 → new epoch → stale marker ignored → gateway boots 'running'. A marker
written during the current instantiation (the live drain) still matches; an s6
respawn of just the gateway (PID 1/init unchanged) keeps the same epoch, so an
in-flight drain is still honoured (D4a reversibility preserved).
The staleness check is lenient and never fail-closed: a legacy marker with no
epoch, a corrupt/contentless marker, or an environment with no /proc (epoch
unavailable) all degrade to the original presence-only behaviour. NAS is
untouched — it only ever POSTs begin/cancel-drain over HTTP; the marker file is
purely gateway-internal IPC.
The fix is entirely within gateway/drain_control.py; the watcher and the
dashboard endpoint go through the same drain_requested()/write_drain_request()
chokepoints and need no functional change.
Tasks 2.1 + 2.2 + 2.3 of the safe-shutdown plan — the reversible
quiesce-without-restart machinery NAS drives during a lifecycle action (D4a).
These ship together because the endpoint, the control channel, and the gateway
state machine are one coherent slice.
2.2 — control channel (gateway/drain_control.py, new):
The dashboard has no HTTP path into a running gateway (guardrails: "there is NO
external control channel into a running gateway"); restart/drain is driven only
by markers the gateway reacts to. So begin/cancel-drain writes/removes a
presence-based marker .drain_request.json (HERMES_HOME-scoped, atomic write,
never-raises read; a corrupt marker reads as present-contentless → fail-safe
toward quiescing). This is Q-B option A.
2.2 — gateway state machine (gateway/run.py):
- _external_drain_active flag, DISTINCT from the shutdown _draining flag: this
one does NOT exit the process and is fully reversible.
- _enter_external_drain / _exit_external_drain: idempotent transitions that
flip gateway_state→draining / →running via _update_runtime_status (preserving
the live active_agents count). exit refuses to revert to running during a
real shutdown or after the loop stops (shutdown wins).
- _drain_control_watcher: 1s background task (modelled on _handoff_watcher)
reconciling accept-state with the marker; honours a marker that survived a
restart on its first tick. Registered alongside the other watchers in start.
- New-turn accept gate in _handle_message, placed BEFORE the session-slot
claim: when draining, refuse to START a new turn (so active_agents can only
fall → no TOCTOU race), while in-flight turns finish untouched. Internal/
system events (restart-recovery replays, bg-process completions) bypass it.
2.1 — endpoint (hermes_cli/web_server.py):
POST /api/gateway/drain {action: drain|cancel}. Authenticated by the Task-2.0a
token seam (the drain plugin registered this exact path as a token route);
attributes the request to the verified token principal. Begin writes the
marker, cancel removes it — the gateway process owns the actual transition.
Force-override (D6) is NOT here; it maps onto the existing immediate
/api/gateway/restart force path.
Tests (mocked — necessary-not-sufficient; the HARD live gate Q-B is next):
- tests/gateway/test_external_drain_control.py — marker contract (write/clear/
read/corrupt/atomic), state machine (enter/exit/idempotency/shutdown-wins/
loop-stopped), watcher reconcile-enter-then-exit, new-turn refusal, and
in-flight-not-interrupted. 15 tests.
- tests/hermes_cli/test_web_server.py — /api/gateway/drain begin/default-begin/
cancel/cancel-idempotent/bad-action-400. 6 tests.
- dashboard.drain_auth config section already added in 2.0b commit.
All touched suites green: 301 (gateway+auth) + 9 (web_server endpoints) passed.
Intentionally deferred:
- HARD live-validation gate (Q-B): real isolated `hermes gateway run`, drive a
real begin-drain marker, prove the 5-point checklist a–e.
- Spec-doc status flip + Phase-2 PR.
Build status: external-drain, restart-drain, status, dashboard-auth, drain-plugin,
token-auth, and web_server-endpoint suites green.
kshitij