Create production installation guide

docs/SETUP_PROD.md

@@ -45,4 +45,81 @@ The OTA update is then located in `build/main.bin`
 * DHCP configured on the network
 
 ## Configure server
-TODO
+
+### Create a user dedicated to the central
+```bash
+sudo adduser --disabled-login central
+```
+
+### Install binary
+You can use `scp` to copy the binary to the target server:
+
+```bash
+scp central_backend/target/release/central_backend pierre@central:/home/pierre
+```
+
+Then the executable must be installed system-wide:
+
+```bash
+sudo mv central_backend /usr/local/bin/
+```
+
+### Create configuration file
+Create a configuration file in `/home/central/config.yaml`:
+
+```bash
+sudo touch /home/central/config.yaml
+sudo chown central:central /home/central/config.yaml
+sudo chmod 400 /home/central/config.yaml
+sudo nano /home/central/config.yaml
+```
+
+Sample configuration:
+
+```conf
+SECRET=RANDOM_VALUE
+COOKIE_SECURE=true
+LISTEN_ADDRESS=0.0.0.0:443
+ADMIN_USERNAME=admin
+ADMIN_PASSWORD=FIXME
+HOSTNAME=central
+STORAGE=/home/central/storage
+FRONIUS_ORIG=http://10.0.0.10
+```
+
+### Test configuration
+Run the following command to check if the configuration is working:
+
+```bash
+sudo -u central central_backend -c /home/central/config.yaml
+```
+
+### Create systemd unit file
+Once you confirmed the configuration is working, you can configure a system service, in `/etc/systemd/system/central.service`:
+
+```conf
+[Unit]
+Description=Central backend server
+After=syslog.target
+After=network.target
+
+[Service]
+RestartSec=2s
+Type=simple
+User=central
+Group=central
+WorkingDirectory=/home/central
+ExecStart=/usr/local/bin/central_backend -c /home/central/config.yaml
+Restart=always
+Environment=USER=central 
+HOME=/home/central
+
+[Install]
+WantedBy=multi-user.target
+```
+
+Enable & start service:
+```bash
+sudo systemctl enable central
+sudo systemctl start central
+```