# systemd units

Two roles, two units. Copy the one you need to `/etc/systemd/system/`, put the
matching configuration in `/etc/llmgw/`, and `systemctl enable --now` it.

## The control plane — `llmgw-server.service`

Runs unprivileged. It needs to read its own TLS key, so that file must belong to
the `llmgw` user and nothing else:

```
useradd --system --home-dir /var/lib/llmgw --shell /usr/sbin/nologin llmgw
chown llmgw:llmgw /etc/llmgw/server-key.pem
chmod 0400 /etc/llmgw/server-key.pem
```

`StateDirectory=llmgw` creates `/var/lib/llmgw` with the right owner, which is
where the store belongs. `ProtectSystem=strict` makes the rest of the filesystem
read-only, so anything else it writes to has to be named explicitly.

## The agent — `llmgw-agent.service`

Runs as root, because it launches engines and needs device access.

`KillMode=process` is the line that matters and the reason this file exists
rather than being generated. Without it, systemd kills the whole control group
on stop — including the engines, which hold a loaded model and are serving
traffic. Engines are meant to outlive an agent restart: the router talks to them
directly, and the agent adopts them again when it comes back. Taking them down
with the agent turns a thirty-second upgrade into a full model reload on every
node.

systemd will log `Found left-over process ... in control group while starting
unit. Ignoring.` on the next start. That is the mechanism working, not a fault.