Make SERIAL_DEVICE unoverrideable in container

Force users to make a mapping. If we make it overrideable, users may
be tempted to set SERIAL_DEVICE=/dev/ttyUSB0 and map that device
directly, without relying on /dev/serial/by-id. This is to be
discouraged.

Dockerfile

@@ -3,4 +3,4 @@ WORKDIR /app
 COPY requirements.txt ./
 RUN pip install --no-cache-dir -r requirements.txt
 COPY . .
-CMD [ "./mqtt4dsmr.py" ]
+CMD [ "env", "SERIAL_DEVICE=/dev/ttyDSMR", "./mqtt4dsmr.py" ]

README.md

@@ -326,6 +326,24 @@ for more information. (Optional)
 
 `V4`
 
+</td>
+</tr>
+<tr>
+<td>
+
+`SERIAL_DEVICE`
+
+</td>
+<td>
+
+Path to serial device file.
+
+**NOTE:** This option is for testing purposes only. When running in a
+container, `SERIAL_DEVICE` always has the value `/dev/ttyDSMR` and
+cannot be overridden. Make sure to map the host device accordingly.
+
+</td>
+<td>
 </td>
 </tr>
 </table>

config.py

@@ -57,7 +57,7 @@ def __init__(self):
         dsmr_version = get_env_opt('DSMR_VERSION', dsmr_versions, False, 'V4')
 
         self.SERIAL_SETTINGS = getattr(dsmr_parser.clients, serial_settings_pfx + serial_settings)
-        self.SERIAL_PORT = get_env_opt('SERIAL_PORT', str, False, '/dev/ttyDSMR')
+        self.SERIAL_DEVICE = get_env_opt('SERIAL_DEVICE', str, True)
         self.DSMR_VERSION = getattr(telegram_specifications, dsmr_version)
 
         self.MQTT_HOST         = get_env_opt('MQTT_HOST', str, True)

mqtt4dsmr.py

@@ -155,7 +155,7 @@ def main():
     client.publish(avail, 'online', retain=True)
 
     serial_reader = SerialReader(
-        device=cfg.SERIAL_PORT,
+        device=cfg.SERIAL_DEVICE,
         serial_settings=cfg.SERIAL_SETTINGS,
         telegram_specification=cfg.DSMR_VERSION
     )