init comment-service

services/comment-service/comment_service/models/config.py

@@ -0,0 +1,66 @@
+from typing import Any, List
+
+from pydantic import computed_field
+from pydantic.fields import FieldInfo
+from pydantic_settings import BaseSettings, EnvSettingsSource
+from pydantic_settings.main import BaseSettings
+from pydantic_settings.sources import PydanticBaseSettingsSource
+
+
+class ConfigSource(EnvSettingsSource):
+    """Responsible for loading config options from environment variables."""
+    def prepare_field_value(self, field_name: str, field: FieldInfo, value: Any, value_is_complex: bool) -> Any:
+        if field_name == "kafka_brokers":
+            # Comma delimit the kafka brokers.
+            if value == None:
+                return None
+            return value.split(",")
+
+        return super().prepare_field_value(field_name, field, value, value_is_complex)
+
+
+class Config(BaseSettings):
+    """The service configuration loaded from environment
+    variables.
+    
+    Attributes:
+        postgres_user (str): Loaded from the 'POSTGRES_USER' envvar.
+        postgres_pass (str): Loaded from the 'POSTGRES_PASS' envvar.
+        postgres_host (str): Loaded from the 'POSTGRES_HOST' envvar.
+        postgres_database (str): Loaded from the 'POSTGRES_DATABASE' envvar.
+        redis_host (str): Loaded from the 'REDIS_HOST' envvar.
+        redis_pass (str): Loaded from the 'REDIS_PASS' envvar.
+        kafka_brokers (list[str]): Loaded and comma delmited from the 'KAFKA_BROKERS' envvar.
+        postgres_dsn (str): Computed when accessed the first time. (@property)
+    
+    """
+    postgres_user: str
+    postgres_pass: str
+    postgres_host: str
+    postgres_database: str
+
+    redis_host: str
+    redis_pass: str
+
+    kafka_brokers: List[str]
+
+    @computed_field
+    @property
+    def postgres_dsn(self) -> str:
+        """Uses the postgres_user, postgres_pass, postgres_host,
+        and postgres_database options to assemble a DSN.
+
+        Returns:
+            str: DSN for connecting to the database.
+        
+        """
+        return "postgresql+asyncpg://{user}:{password}@{host}/{db}".format(
+            user=self.postgres_user,
+            password=self.postgres_pass,
+            host=self.postgres_host,
+            db=self.postgres_database
+        )
+    
+    @classmethod
+    def settings_customise_sources(cls, settings_cls: type[BaseSettings], *args, **kwargs) -> tuple[PydanticBaseSettingsSource, ...]:
+        return (ConfigSource(settings_cls), )