wip: POC of three metadata sources

python/seldon_core/metadata.py

@@ -1,13 +1,11 @@
 import os
-import json
 import logging
 
 
 logger = logging.getLogger(__name__)
 
 NONIMPLEMENTED_MSG = "NOT_IMPLEMENTED"
 
-ENV_MODEL_METADATA = "MODEL_METADATA"
 ENV_MODEL_IMAGE = "PREDICTIVE_UNIT_IMAGE"
 image = os.environ.get(ENV_MODEL_IMAGE, f"{NONIMPLEMENTED_MSG}:{NONIMPLEMENTED_MSG}")
 image_name, image_version = image.split(":")
@@ -46,8 +44,10 @@ def __init__(
         logger.debug(f"Successfully validated ModelMetadata: {self}")
 
     def validate(self):
+        if self.versions is None:
+            self.versions = []
         if not isinstance(self.versions, (list, tuple)):
-            self.versions = [self.versions]
+            logger.error("ModelMetadata versions must be a list or tuple.")
         self.versions = [str(x) for x in self.versions]
 
     @staticmethod
@@ -110,9 +110,3 @@ def from_json(data):
             inputs=inputs,
             outputs=outputs,
         )
-
-    @staticmethod
-    def from_env():
-        data = json.loads(os.environ.get(ENV_MODEL_METADATA, "{}"))
-        logger.debug(f"Reading metadata from environment: {data}")
-        return ModelMetadata.from_json(data)

python/seldon_core/seldon_methods.py

@@ -1,3 +1,6 @@
+import os
+import yaml
+import json
 import logging
 from seldon_core.utils import (
     extract_request_parts,
@@ -507,9 +510,9 @@ def health_status(
     )
 
 
-def metadata(user_model: Any) -> Dict:
+def init_metadata(user_model: Any) -> Dict:
     """
-    Call the user model to get the model metadata
+    Call the user model to get the model init_metadata
 
     Parameters
     ----------
@@ -519,25 +522,32 @@ def metadata(user_model: Any) -> Dict:
     -------
       Model Metadata
     """
-    if hasattr(user_model, "metadata"):
+    # meta1: load metadata defined in the user_model instance
+    if hasattr(user_model, "init_metadata"):
         try:
-            # Returned metadata can be dict or ModelMetadata
-            metadata = user_model.metadata()
-            if isinstance(metadata, dict):
-                metadata = ModelMetadata.from_json(metadata)
-            elif not isinstance(metadata, ModelMetadata):
-                raise SeldonMicroserviceException(
-                    "user_model.metadata did not return ModelMetadata or dict instance",
-                    status_code=500,
-                    reason="MICROSERVICE_BAD_MODEL_METADATA",
-                )
-            # After validating that we got a correct output and in case of dict creating
-            # ModelMetadata instance we can return json.
-            return metadata.json()
+            meta1 = user_model.init_metadata()
         except SeldonNotImplementedError:
+            meta1 = {}
             pass
+    else:
+        meta1 = {}
+
+    # meta2: load metadata from yaml file
+    file_path = os.environ.get("MODEL_METADATA_FILE", "metadata.yaml")
+    try:
+        with open(file_path, "r") as f:
+            meta2 = yaml.load(f.read())
+    except FileNotFoundError:
+        meta2 = {}
+    except yaml.YAMLError:
+        logger.error(
+            f"metadata file {file_path} present but does not contain valid yaml"
+        )
+        meta2 = {}
+
+    # meta3: load metadata from environmental variable
+    meta3 = json.loads(os.environ.get("MODEL_METADATA", "{}"))
 
-    # If there is no "metadata" method in "user_model" or "SeldonNotImplementedError"
-    # is raised we fallback to read from environmental variable
-    metadata = ModelMetadata.from_env()
+    # Cast to ModelMetadata and back in order to validate
+    metadata = ModelMetadata.from_json({**meta1, **meta2, **meta3})
     return metadata.json()

python/seldon_core/user_model.py

@@ -119,6 +119,9 @@ def health_status_raw(self) -> prediction_pb2.SeldonMessage:
     def metadata(self) -> Dict:
         raise SeldonNotImplementedError("metadata is not implemented")
 
+    def init_metadata(self) -> Dict:
+        raise SeldonNotImplementedError("init_metadata is not implemented")
+
 
 def client_custom_tags(user_model: SeldonComponent) -> Dict:
     """

python/seldon_core/wrapper.py

@@ -25,6 +25,8 @@ def get_rest_microservice(user_model, seldon_metrics):
 
     _set_flask_app_configs(app)
 
+    metadata_data = seldon_core.seldon_methods.init_metadata(user_model)
+
     if hasattr(user_model, "model_error_handler"):
         logger.info("Registering the custom error handler...")
         app.register_blueprint(user_model.model_error_handler)
@@ -127,9 +129,8 @@ def HealthStatus():
     @app.route("/metadata", methods=["GET"])
     def Metadata():
         logger.debug("REST Metadata Request")
-        response = seldon_core.seldon_methods.metadata(user_model)
-        logger.debug("REST Metadata Response: %s", response)
-        return jsonify(response)
+        logger.debug("REST Metadata Response: %s", metadata_data)
+        return jsonify(metadata_data)
 
     return app