fix(backend-python): fix support for custom options during startup an…

…d add basic doc strings

backend-python/src/telestion/backend/lib.py

@@ -12,10 +12,15 @@
 
 @dataclass
 class Service:
+    """Helper Class for starting NATS clients also exposing the parsed config."""
     nc: NatsClient | None   # None if Options.nats = False
+    """Configured and started NATS client for this service."""
     data_dir: Path
+    """Directory where all data (temporary and persistent) should be stored."""
     service_name: str
+    """Name of this service. Note that it is not necessarily unique!"""
     config: TelestionConfig
+    """TelestionConfig instance for this service """
 
     # wrapper methods for NatsClient instance for convenience
     async def publish(self, **kwargs) -> None:
@@ -45,18 +50,25 @@ async def close(self) -> None:
 
 @dataclass
 class Options:
+    """Storing a custom configuration which overwrites the parsed config during startup of the Telestion service."""
     nats: bool = True
+    """Whether a service should use nats. If set to False no nats client is set up during startup"""
     # (officially) we don't support int keys, btw...
     overwrite_args: dict[str, Any] | None = None
+    """Arguments overwriting the parsed config of a service."""
     custom_nc: NatsClient | None = None
+    """Custom nats client. During startup no configuration takes place if present."""
 
     def without_nats(self) -> 'Options':
-        return replace(self, nats=False)
+        """Returns a copy of this Options instance with nats switched off."""
+        return replace(self, nats=False, custom_nc=None)
 
     def with_overwrite_args(self, **kwargs) -> 'Options':
+        """Returns a copy of this Options instance with different custom arguments."""
         return replace(self, overwrite_args=kwargs)
 
     def with_custom_nc(self, nats_client: NatsClient) -> 'Options':
+        """Returns a copy of this Options instance with a custom client."""
         return replace(self, custom_nc=nats_client)
 
 
@@ -79,12 +91,13 @@ async def _respond_hc(msg):
 
 
 async def start_service(opts: Options = None) -> Service:
+    """Creates a Service for the given Options and the parsed config and spins up a new NATS client if configured so."""
     if opts is None:
         opts = Options()
 
     config = build_config()
     if opts.overwrite_args is not None:
-        config.update(opts.overwrite_args)
+        config = config.model_copy(update=opts.overwrite_args)
 
     service = Service(opts.custom_nc, config.data_dir, config.service_name, config)
 

backend-python/src/telestion/backend/test.py

@@ -1,7 +1,7 @@
 import asyncio
 
 from telestion.backend.config import build_config, TelestionConfig
-from telestion.backend.lib import start_service
+from telestion.backend.lib import start_service, Options
 
 
 async def main():
@@ -10,8 +10,9 @@ async def main():
     sys.argv.extend(['--dev', '--NATS_URL', 'nats://172.21.73.221:4222'])
     _config = build_config(TelestionConfig)
     print(_config)
-    service = await start_service()
+    service = await start_service(Options().with_overwrite_args(test="foo"))
     await service.nc.close()
+    print(service.config)
 
 
 if __name__ == '__main__':