readme update

server/README.md

@@ -135,6 +135,32 @@ flask --app app create-admin
 Running `create-admin` for an existing username resets its password and grants
 `is_admin=True`. Log in at `/login`; you land on `/home`.
 
+When the main app runs as a systemd service, run the command as the same user
+and from the same directory as the service (see `yggdrasil.service`):
+
+```bash
+cd /home/mateusz/prog/yggdrasil/server
+sudo -u mateusz .venv/bin/flask --app app create-admin
+```
+
+To pass credentials without an interactive prompt:
+
+```bash
+sudo -u mateusz env ADMIN_USERNAME=admin ADMIN_PASSWORD='secret' \
+    .venv/bin/flask --app app create-admin
+```
+
+If the unit sets `USERS_DB_PATH` or `USERS_DATABASE_URL`, add the same variable
+to the command, for example:
+
+```bash
+sudo -u mateusz env USERS_DB_PATH=/data/main_app.db \
+    .venv/bin/flask --app app create-admin
+```
+
+The service does not need to be restarted; the new account is used on the next
+login.
+
 ## Running
 
 The first argument selects the app (`main` or `sensors`), the second the port.
@@ -199,12 +225,49 @@ SENSORS_API_URL=http://localhost:5432 ./run-prod.sh main 8000
 
 ### systemd services
 
+Main app only:
+
+```bash
+sudo cp yggdrasil.service /etc/systemd/system/
+sudo systemctl daemon-reload
+sudo systemctl enable --now yggdrasil
+```
+
+Main app and sensors API:
+
 ```bash
 sudo cp yggdrasil.service yggdrasil-sensors.service /etc/systemd/system/
 sudo systemctl daemon-reload
 sudo systemctl enable --now yggdrasil yggdrasil-sensors
 ```
 
+Check whether the main service is active:
+
+```bash
+systemctl status yggdrasil
+systemctl is-active yggdrasil      # prints: active / inactive / failed
+systemctl is-enabled yggdrasil     # prints: enabled / disabled
+```
+
+Quick HTTP check:
+
+```bash
+curl -I http://localhost:8000/login
+ss -ltnp | grep ':8000'
+```
+
+Logs:
+
+```bash
+journalctl -u yggdrasil -f
+journalctl -u yggdrasil -n 50 --no-pager
+journalctl -u yggdrasil-sensors -f   # if the sensors service is installed
+```
+
+The unit files currently use `User=mateusz` and
+`WorkingDirectory=/home/mateusz/prog/yggdrasil/server`; adjust them if the
+deployment path or user is different.
+
 | Service | Port | Routes |
 |---|---|---|
 | main | 8000 | `/`, `/login`, `/home`, `/sensors`, `/api/docs`, `/api/*` (proxy) |