Pedantic config management using Pydantic

.env

ENV_STATE="dev" # or prod

DEV_REDIS_HOST="127.0.0.1"
DEV_REDIS_PORT="4000"

PROD_REDIS_HOST="127.0.0.2"
PROD_REDIS_PORT="5000"

configs.py

# configs.py

from typing import Optional

from pydantic import BaseSettings, Field, BaseModel


class AppConfig(BaseModel):
    """Application configurations."""

    VAR_A: int = 33
    VAR_B: float = 22.0


class GlobalConfig(BaseSettings):
    """Global configurations."""

    # This variable will be loaded from the .env file. However, if there is a
    # shell environment variable having the same name, that will take precedence.

    ENV_STATE: Optional[str] = Field(None, env="ENV_STATE")
    APP_CONFIG: AppConfig = AppConfig()
    REDIS_PASS: Optional[str] = Field(None, env="REDIS_PASS")

    class Config:
        """Loads the dotenv file."""

        env_file: str = ".env"


class DevConfig(GlobalConfig):
    """Development configurations."""

    REDIS_HOST: Optional[str] = Field(None, env="DEV_REDIS_HOST")
    REDIS_PORT: Optional[int] = Field(None, env="DEV_REDIS_PORT")


class ProdConfig(GlobalConfig):
    """Production configurations."""

    REDIS_HOST: Optional[str] = Field(None, env="PROD_REDIS_HOST")
    REDIS_PORT: Optional[int] = Field(None, env="PROD_REDIS_PORT")


class FactoryConfig:
    """Returns a config instance dependending on the ENV_STATE variable."""

    def __init__(self, env_state: Optional[str]):
        self.env_state = env_state

    def __call__(self):
        if self.env_state == "dev":
            return DevConfig()

        elif self.env_state == "prod":
            return ProdConfig()


cnf = FactoryConfig(GlobalConfig().ENV_STATE)()
print(cnf.__repr__())