# systemd Service Installation

Quick setup to run system2mqtt as a systemd service on Linux.

## Installation Steps

1. **Create dedicated user:**
   ```bash
   sudo useradd -r -s /usr/sbin/nologin -d /opt/system2mqtt system2mqtt
   ```

2. **Install system to /opt/system2mqtt:**
   ```bash
   sudo mkdir -p /opt/system2mqtt
   sudo cp -r system2mqtt.py collectors config.yaml.example run.sh /opt/system2mqtt/
   sudo cp requirements.txt /opt/system2mqtt/
   sudo chmod +x /opt/system2mqtt/run.sh
   sudo chown -R system2mqtt:system2mqtt /opt/system2mqtt
   ```

3. **Configure:**
   ```bash
   # Copy and edit config (in user's home directory)
   sudo -u system2mqtt mkdir -p ~system2mqtt/.config/system2mqtt
   sudo -u system2mqtt cp /opt/system2mqtt/config.yaml.example ~system2mqtt/.config/system2mqtt/config.yaml
   sudo nano ~system2mqtt/.config/system2mqtt/config.yaml
   
   # OR use environment variables in .env
   sudo nano /opt/system2mqtt/.env
   sudo chown system2mqtt:system2mqtt /opt/system2mqtt/.env
   ```

4. **Install systemd service:**
   ```bash
   sudo cp system2mqtt.service /etc/systemd/system/
   sudo systemctl daemon-reload
   sudo systemctl enable system2mqtt
   sudo systemctl start system2mqtt
   ```

5. **Check status:**
   ```bash
   sudo systemctl status system2mqtt
   sudo journalctl -u system2mqtt -f
   ```

## Service Management

- **Start:** `sudo systemctl start system2mqtt`
- **Stop:** `sudo systemctl stop system2mqtt`
- **Restart:** `sudo systemctl restart system2mqtt`
- **Logs:** `sudo journalctl -u system2mqtt -f`
- **Enable on boot:** `sudo systemctl enable system2mqtt`
- **Disable on boot:** `sudo systemctl disable system2mqtt`

## Notes

- Service runs as unprivileged `system2mqtt` user
- User is member of `adm` and `systemd-journal` groups for system metrics access
- ZFS (read-only): On many systems, read-only queries like `zpool status` and `zpool list` work without special privileges. If they fail on your host, consider one of these options:
   - Add the user to a `zfs` group if present (Debian/Ubuntu with `zfsutils-linux` often provide it):
      ```bash
      sudo usermod -aG zfs system2mqtt
      sudo systemctl restart system2mqtt
      ```
   - Allow read-only ZFS commands via sudoers without a password:
      ```bash
      echo "system2mqtt ALL=(ALL) NOPASSWD: /usr/sbin/zpool, /usr/sbin/zfs" | sudo tee /etc/sudoers.d/system2mqtt
      sudo visudo -c
      ```
   - Use ZFS delegation (if supported in your setup) to grant specific permissions:
      ```bash
      sudo zfs allow system2mqtt snapshot,send,receive YOUR_POOL
      ```
- `run.sh` automatically creates venv, installs/updates dependencies on each start
- Auto-restarts on failure (RestartSec=10)
- Reads environment from `/opt/system2mqtt/.env` if present
- Logs to systemd journal (view with `journalctl`)