Add function to retrieve the microgrid metadata

So far the microgrid metadata is needed to get the ID and
the location of the microgrid. The metadata is retrieved
from the microgrid API through the gRPC call GetMicrogridMetadata.

Signed-off-by: Daniel Zullo <[email protected]>

Author: daniel-zullo-frequenz

src/frequenz/sdk/microgrid/client/_client.py

@@ -15,6 +15,7 @@
 from frequenz.api.microgrid import microgrid_pb2 as microgrid_pb
 from frequenz.api.microgrid.microgrid_pb2_grpc import MicrogridStub
 from frequenz.channels import Broadcast, Receiver, Sender
+from google.protobuf.empty_pb2 import Empty  # pylint: disable=no-name-in-module
 
 from ..._internal._constants import RECEIVER_MAX_SIZE
 from ..component import (
@@ -30,6 +31,7 @@
     _component_metadata_from_protobuf,
     _component_type_from_protobuf,
 )
+from ..metadata import Location, Metadata
 from ._connection import Connection
 from ._retry import LinearBackoff, RetryStrategy
 
@@ -62,6 +64,14 @@ async def components(self) -> Iterable[Component]:
             Iterator whose elements are all the components in the microgrid.
         """
 
+    @abstractmethod
+    async def metadata(self) -> Metadata:
+        """Fetch the microgrid metadata.
+
+        Returns:
+            the microgrid metadata.
+        """
+
     @abstractmethod
     async def connections(
         self,
@@ -259,6 +269,36 @@ async def components(self) -> Iterable[Component]:
 
         return result
 
+    async def metadata(self) -> Metadata:
+        """Fetch the microgrid metadata.
+
+        If there is an error fetching the metadata, the microgrid ID and
+        location will be set to None.
+
+        Returns:
+            the microgrid metadata.
+        """
+        microgrid_metadata: microgrid_pb.MicrogridMetadata | None = None
+        try:
+            microgrid_metadata = await self.api.GetMicrogridMetadata(
+                Empty(),
+                timeout=int(DEFAULT_GRPC_CALL_TIMEOUT),
+            )  # type: ignore[misc]
+        except grpc.aio.AioRpcError:
+            _logger.exception("The microgrid metadata is not available.")
+
+        if not microgrid_metadata:
+            return Metadata()
+
+        location: Location | None = None
+        if microgrid_metadata.location:
+            location = Location(
+                latitude=microgrid_metadata.location.latitude,
+                longitude=microgrid_metadata.location.longitude,
+            )
+
+        return Metadata(microgrid_id=microgrid_metadata.microgrid_id, location=location)
+
     async def connections(
         self,
         starts: set[int] | None = None,