Make serverless alpha feature (#1928)

* Hide AWS Lambda feature server behind experimental flag

Signed-off-by: Felix Wang <wangfelix98@gmail.com>

* Ensure that registry is on S3 for AWS Lambda feature server

Signed-off-by: Felix Wang <wangfelix98@gmail.com>

sdk/python/feast/errors.py

@@ -294,3 +294,10 @@ def __init__(self, resource_name: str):
         super().__init__(
             f"The AWS API Gateway {resource_name} should have been created properly, but does not exist."
         )
+
+
+class IncompatibleRegistryStoreClass(Exception):
+    def __init__(self, actual_class: str, expected_class: str):
+        super().__init__(
+            f"The registry store class was expected to be {expected_class}, but was instead {actual_class}."
+        )

sdk/python/feast/flags.py

@@ -1,10 +1,12 @@
 FLAG_ALPHA_FEATURES_NAME = "alpha_features"
 FLAG_ON_DEMAND_TRANSFORM_NAME = "on_demand_transforms"
 FLAG_PYTHON_FEATURE_SERVER_NAME = "python_feature_server"
+FLAG_AWS_LAMBDA_FEATURE_SERVER_NAME = "aws_lambda_feature_server"
 ENV_FLAG_IS_TEST = "IS_TEST"
 
 FLAG_NAMES = {
     FLAG_ALPHA_FEATURES_NAME,
     FLAG_ON_DEMAND_TRANSFORM_NAME,
     FLAG_PYTHON_FEATURE_SERVER_NAME,
+    FLAG_AWS_LAMBDA_FEATURE_SERVER_NAME,
 }

sdk/python/feast/flags_helper.py

@@ -37,3 +37,7 @@ def enable_on_demand_feature_views(repo_config: RepoConfig) -> bool:
 
 def enable_python_feature_server(repo_config: RepoConfig) -> bool:
     return feature_flag_enabled(repo_config, flags.FLAG_PYTHON_FEATURE_SERVER_NAME)
+
+
+def enable_aws_lambda_feature_server(repo_config: RepoConfig) -> bool:
+    return feature_flag_enabled(repo_config, flags.FLAG_AWS_LAMBDA_FEATURE_SERVER_NAME)

sdk/python/feast/infra/aws.py

@@ -19,15 +19,20 @@
 from feast.errors import (
     AwsAPIGatewayDoesNotExist,
     AwsLambdaDoesNotExist,
+    ExperimentalFeatureNotEnabled,
+    IncompatibleRegistryStoreClass,
     RepoConfigPathDoesNotExist,
     S3RegistryBucketForbiddenAccess,
     S3RegistryBucketNotExist,
 )
 from feast.feature_table import FeatureTable
 from feast.feature_view import FeatureView
+from feast.flags import FLAG_AWS_LAMBDA_FEATURE_SERVER_NAME
+from feast.flags_helper import enable_aws_lambda_feature_server
 from feast.infra.passthrough_provider import PassthroughProvider
 from feast.infra.utils import aws_utils
 from feast.protos.feast.core.Registry_pb2 import Registry as RegistryProto
+from feast.registry import get_registry_store_class_from_scheme
 from feast.registry_store import RegistryStore
 from feast.repo_config import RegistryConfig
 from feast.version import get_version
@@ -62,6 +67,22 @@ def update_infra(
         )
 
         if self.repo_config.feature_server and self.repo_config.feature_server.enabled:
+            if not enable_aws_lambda_feature_server(self.repo_config):
+                raise ExperimentalFeatureNotEnabled(FLAG_AWS_LAMBDA_FEATURE_SERVER_NAME)
+
+            # Since the AWS Lambda feature server will attempt to load the registry, we
+            # only allow the registry to be in S3.
+            registry_path = (
+                self.repo_config.registry
+                if isinstance(self.repo_config.registry, str)
+                else self.repo_config.registry.path
+            )
+            registry_store_class = get_registry_store_class_from_scheme(registry_path)
+            if registry_store_class != S3RegistryStore:
+                raise IncompatibleRegistryStoreClass(
+                    registry_store_class.__name__, S3RegistryStore.__name__
+                )
+
             image_uri = self._upload_docker_image(project)
             _logger.info("Deploying feature server...")