chore(flagd): Add sync metadata disabled (#211)

* chore(flagd): add disable metadata option

Signed-off-by: Maks Osowski <[email protected]>

* chore(flagd): Minimally refactor GrpcWatcher.listen() to pass ruff complexity pre-commit

Signed-off-by: Maks Osowski <[email protected]>

* Update providers/openfeature-provider-flagd/src/openfeature/contrib/provider/flagd/config.py

Co-authored-by: Anton Grübel <[email protected]>
Signed-off-by: cupofcat <[email protected]>

---------

Signed-off-by: Maks Osowski <[email protected]>
Signed-off-by: cupofcat <[email protected]>
Co-authored-by: Anton Grübel <[email protected]>

Author: cupofcat

providers/openfeature-provider-flagd/src/openfeature/contrib/provider/flagd/config.py

@@ -100,6 +100,7 @@ def __init__(  # noqa: PLR0913
         cert_path: typing.Optional[str] = None,
         default_authority: typing.Optional[str] = None,
         channel_credentials: typing.Optional[grpc.ChannelCredentials] = None,
+        sync_metadata_disabled: typing.Optional[bool] = None,
     ):
         self.host = env_or_default(ENV_VAR_HOST, DEFAULT_HOST) if host is None else host
 
@@ -248,3 +249,11 @@ def __init__(  # noqa: PLR0913
         )
 
         self.channel_credentials = channel_credentials
+
+        # TODO: remove the metadata call entirely after https://github.com/open-feature/flagd/issues/1584
+        # This is a temporary stop-gap solutions to support servers that don't implement sync.GetMetadata
+        # (see: https://buf.build/open-feature/flagd/docs/main:flagd.sync.v1#flagd.sync.v1.FlagSyncService.GetMetadata).
+        # Using this option disables call to sync.GetMetadata
+        # Disabling will prevent static context from flagd being used in evaluations.
+        # GetMetadata and this option will be removed.
+        self.sync_metadata_disabled = sync_metadata_disabled

providers/openfeature-provider-flagd/src/openfeature/contrib/provider/flagd/provider.py

@@ -64,6 +64,7 @@ def __init__(  # noqa: PLR0913
         cert_path: typing.Optional[str] = None,
         default_authority: typing.Optional[str] = None,
         channel_credentials: typing.Optional[grpc.ChannelCredentials] = None,
+        sync_metadata_disabled: typing.Optional[bool] = None,
     ):
         """
         Create an instance of the FlagdProvider
@@ -106,6 +107,7 @@ def __init__(  # noqa: PLR0913
             cert_path=cert_path,
             default_authority=default_authority,
             channel_credentials=channel_credentials,
+            sync_metadata_disabled=sync_metadata_disabled,
         )
         self.enriched_context: dict = {}
 

providers/openfeature-provider-flagd/src/openfeature/contrib/provider/flagd/resolvers/process/connector/grpc_watcher.py

@@ -6,6 +6,7 @@
 
 import grpc
 from google.protobuf.json_format import MessageToDict
+from google.protobuf.struct_pb2 import Struct
 
 from openfeature.evaluation_context import EvaluationContext
 from openfeature.event import ProviderEventDetails
@@ -162,24 +163,36 @@ def shutdown(self) -> None:
         self.active = False
         self.channel.close()
 
+    def _create_request_args(self) -> dict:
+        request_args = {}
+        if self.selector is not None:
+            request_args["selector"] = self.selector
+        if self.provider_id is not None:
+            request_args["provider_id"] = self.provider_id
+
+        return request_args
+
     def listen(self) -> None:
         call_args = (
             {"timeout": self.streamline_deadline_seconds}
             if self.streamline_deadline_seconds > 0
             else {}
         )
-        request_args = {}
-        if self.selector is not None:
-            request_args["selector"] = self.selector
-        if self.provider_id is not None:
-            request_args["provider_id"] = self.provider_id
+        request_args = self._create_request_args()
 
         while self.active:
             try:
-                context_values_request = sync_pb2.GetMetadataRequest()
-                context_values_response: sync_pb2.GetMetadataResponse = (
-                    self.stub.GetMetadata(context_values_request, wait_for_ready=True)
-                )
+                context_values_response: sync_pb2.GetMetadataResponse
+                if self.config.sync_metadata_disabled:
+                    context_values_response = sync_pb2.GetMetadataResponse(
+                        metadata=Struct()
+                    )
+                else:
+                    context_values_request = sync_pb2.GetMetadataRequest()
+                    context_values_response = self.stub.GetMetadata(
+                        context_values_request, wait_for_ready=True
+                    )
+
                 context_values = MessageToDict(context_values_response)
 
                 request = sync_pb2.SyncFlagsRequest(**request_args)