Three holes in the systemd integration:
1. _spawn_agent_via_systemd only restarted decnet-agent.service, leaving
decnet-forwarder.service running the pre-update code (same /opt/decnet
tree, stale import cache).
2. run_update_self used os.execv regardless of environment — the re-execed
process kept the updater's existing cgroup/capability inheritance but
systemd would notice MainPID change and mark the unit degraded.
3. No path to surface a failed forwarder restart (legacy enrollments have
no forwarder unit).
Now: agent restart first, forwarder restart as best-effort (logged but
non-fatal so legacy workers still update), MainPID still read from the
agent unit. For update-self under systemd, spawn a detached sleep+
systemctl restart so the HTTP response flushes before the unit cycles.
Add deploy/ unit files for every DECNET daemon (agent, updater, api, web,
swarmctl, listener, forwarder). All run as User=decnet with NoNewPrivileges,
ProtectSystem, PrivateTmp, LockPersonality; AmbientCapabilities=CAP_NET_ADMIN
CAP_NET_RAW only on the agent (MACVLAN/scapy). Existing api/web units migrated
to /opt/decnet layout and the same hardening stanza.
Make the updater's _spawn_agent systemd-aware: under systemd (detected via
INVOCATION_ID + systemctl on PATH), `systemctl restart decnet-agent.service`
replaces the Popen path so the new agent inherits the unit's ambient caps
instead of the updater's empty set. _stop_agent becomes a no-op in that mode
to avoid racing systemctl's own stop phase.
Tests cover the dispatcher branch selection, MainPID parsing, and the
systemd no-op stop.
If the agent was started outside the updater (manually, during dev,
or from a prior systemd unit), there is no agent.pid for _stop_agent
to target, so a successful code install leaves the old in-memory
agent process still serving requests. Scan /proc for any decnet agent
command and SIGTERM all matches so restart is reliable regardless of
how the agent was originally launched.
Adds a separate `decnet updater` daemon on each worker that owns the
agent's release directory and installs tarball pushes from the master
over mTLS. A normal `/update` never touches the updater itself, so the
updater is always a known-good rescuer if a bad agent push breaks
/health — the rotation is reversed and the agent restarted against the
previous release. `POST /update-self` handles updater upgrades
explicitly (no auto-rollback).
- decnet/updater/: executor, FastAPI app, uvicorn launcher
- decnet/swarm/updater_client.py, tar_tree.py: master-side push
- cli: `decnet updater`, `decnet swarm update [--host|--all]
[--include-self] [--dry-run]`, `--updater` on `swarm enroll`
- enrollment API issues a second cert (CN=updater@<host>) signed by the
same CA; SwarmHost records updater_cert_fingerprint
- tests: executor, app, CLI, tar tree, enroll-with-updater (37 new)
- wiki: Remote-Updates page + sidebar + SWARM-Mode cross-link
