better validation

charms/worker/k8s/lib/charms/k8s/v0/k8sd_api_manager.py

@@ -35,7 +35,7 @@ class utilises different connection factories (UnixSocketConnectionFactory
 from typing import Any, Dict, Generator, List, Optional, Type, TypeVar
 
 import yaml
-from pydantic import AnyHttpUrl, BaseModel, Field, SecretStr, validator
+from pydantic import AnyHttpUrl, BaseModel, Field, SecretStr, validator, root_validator
 
 # The unique Charmhub library identifier, never change it
 LIBID = "6a5f235306864667a50437c08ba7e83f"
@@ -526,11 +526,17 @@ class FeatureRelationData(BaseModel):
     Attributes:
         name (str): The feature name.
         version (str): The library version that was used to create the feature object.
-        attributes (Dict[str, str]): The serialized Pydantic model representing the feature.
+        attributes (str): The serialized Pydantic model representing the feature configuration.
     """
-    name: Optional[str] = Field(None)
-    version: Optional[str] = Field(None)
-    attributes: Optional[str] = Field(None)
+    name: str
+    version: str
+    attributes: str
+
+    @root_validator(pre=True)
+    def check_data(cls, values):
+        assert 'name' in values, "name must be provided"
+        assert 'version' in values, "version must be provided"
+        assert 'attributes' in values, "attributes must be provided"
 
 class GetKubeConfigResponse(BaseRequestModel):
     """Response model for getting the kubeconfig from the cluster.

charms/worker/k8s/src/charm.py

@@ -63,6 +63,7 @@
 from snap import version as snap_version
 from token_distributor import ClusterTokenType, TokenCollector, TokenDistributor, TokenStrategy
 from typing_extensions import Literal
+from pydantic import ValidationError
 
 # Log messages can be retrieved using juju debug-log
 log = logging.getLogger(__name__)
@@ -165,33 +166,34 @@ def _resolve_feature_relations(self, event: ops.EventBase):
                 raw_relation_data = relation.data[unit]
 
                 if not raw_relation_data:
-                    log.warning("No relation data found for feature relation on %s", relation.name)
+                    log.warning("No relation data found for %s relation", relation.name)
+                    continue
+
+                try:
+                    parsed_relation_data = FeatureRelationData.parse_obj(raw_relation_data)
+                except ValidationError as e:
+                    log.warning("The relation data for %s relation is not valid: %s", relation.name, e)
                     continue
 
-                parsed_relation_data = FeatureRelationData.parse_obj(raw_relation_data)
                 feature_name = parsed_relation_data.name
-                feature_version = parsed_relation_data.version
                 feature_attributes = parsed_relation_data.attributes
 
-                if feature_name and feature_version and feature_attributes:
-                    feature_config_classes: Dict[str, type] = {
-                        "load-balancer": LoadBalancerConfig,
-                        "local-storage": LocalStorageConfig,
-                    }
-                    if not (config_class := feature_config_classes.get(feature_name)):
-                        status.add(ops.BlockedStatus(f"Unsupported feature {feature_name}"))
-                        continue
-
-                    feature_config = config_class.parse_raw(feature_attributes)
-                    log.info("Updating feature [%s] with config [%s]", feature_name, feature_config)
-
-                    cluster_config = UserFacingClusterConfig(**{feature_name: feature_config})
-                    update_request = UpdateClusterConfigRequest(config=cluster_config)
-                    self.api_manager.update_cluster_config(update_request)
-
-                    log.info("Feature [%s] updated", feature_name)
-                else:
-                    log.warning("Couldn't resolve feature relation because the relation data is not valid")
+                feature_config_classes: Dict[str, type] = {
+                    "load-balancer": LoadBalancerConfig,
+                    "local-storage": LocalStorageConfig,
+                }
+                if not (config_class := feature_config_classes.get(feature_name)):
+                    status.add(ops.BlockedStatus(f"Unsupported feature {feature_name}"))
+                    continue
+
+                feature_config = config_class.parse_raw(feature_attributes)
+                log.info("Updating feature [%s] with config [%s]", feature_name, feature_config)
+
+                cluster_config = UserFacingClusterConfig(**{feature_name: feature_config})
+                update_request = UpdateClusterConfigRequest(config=cluster_config)
+                self.api_manager.update_cluster_config(update_request)
+
+                log.info("Feature [%s] updated", feature_name)
 
     def _k8s_info(self, event: ops.EventBase):
         """Send cluster information on the kubernetes-info relation.