Configuración global

Estructura de Settings

# app/config/settings.py
from typing import Annotated, List, Optional
from pydantic import BeforeValidator
from pydantic_settings import BaseSettings, SettingsConfigDict


def parse_cors(v):
    if isinstance(v, str):
        return [o.strip() for o in v.split(",") if o.strip()]
    return v


class Settings(BaseSettings):
    model_config = SettingsConfigDict(
        env_file=".env" if not os.environ.get("RUNNING_IN_DOCKER") else None,
        case_sensitive=True,
        extra="ignore",
    )

    PROJECT_NAME: str
    SECRET_KEY: str
    ALGORITHM: str = "HS256"
    DATABASE_URL: str
    DEBUG: bool = True
    ALLOWED_ORIGINS: Annotated[List[str], BeforeValidator(parse_cors)] = []

lru_cache para get_settings()

from functools import lru_cache

@lru_cache()
def get_settings() -> Settings:
    return Settings()


settings = get_settings()

Re-leer .env por request es caro. lru_cache lo lee una vez por proceso.

Override por entorno

# Local
export DEBUG=true

# Production
export DEBUG=false
export ALLOWED_ORIGINS=https://app.example.com

pydantic-settings lee env vars con prioridad sobre .env.

Settings nested

class RedisSettings(BaseSettings):
    HOST: str = "localhost"
    PORT: int = 6379
    PASSWORD: Optional[str] = None
    model_config = SettingsConfigDict(env_prefix="REDIS_")


class Settings(BaseSettings):
    redis: RedisSettings = RedisSettings()

ENV: REDIS_HOST=foo REDIS_PORT=6380.

Computed properties

class Settings(BaseSettings):
    REDIS_HOST: str
    REDIS_PORT: int

    @property
    def redis_url(self) -> str:
        return f"redis://{self.REDIS_HOST}:{self.REDIS_PORT}"

Test mode override

app/config/database.py ya detecta RUNNING_TESTS=true o pytest en argv → cambia a TEST_DATABASE_NAME y usa NullPool. Ver Configuration.

Secrets en producción

NUNCA pongas secrets en .env commiteado. Opciones:

• AWS Secrets Manager + boto3 startup hook
• Doppler / Infisical
• Kubernetes Secrets vía env

import boto3
import json

def load_secrets() -> dict:
    client = boto3.client("secretsmanager", region_name="us-east-1")
    secret = client.get_secret_value(SecretId="prod/myservice")
    return json.loads(secret["SecretString"])

Feature flags

class Settings(BaseSettings):
    FEATURE_X_ENABLED: bool = False
    FEATURE_Y_ROLLOUT: float = 0.0   # 0.0 - 1.0

if settings.FEATURE_X_ENABLED:
    # nueva implementación
    ...

Para feature flags dinámicos (DB-driven), considera LaunchDarkly / Unleash.