“Decouple” for FastAPI project

In a FastAPI project, you can use the decouple library to separate your staging and production configurations. decouple is a simple, flexible and widely used library that allow to store your configurations in a .env file and easily read them in your Python code.

Here’s an example of how you can use decouple to separate your staging and production configurations:

1. Install the decouple library by running pip install decouple in your terminal.
2. Create a .env file in the root of your project and specify your staging and production configurations. For example:

# .env
DEBUG=True
DATABASE_URL=sqlite:///./test.db
SECRET_KEY=mysecretkey

1. Import the config object from the decouple library in your main.py file and use it to access the configurations in your code.

from decouple import config

DEBUG = config("DEBUG", default=False, cast=bool)
DATABASE_URL = config("DATABASE_URL", default="sqlite:///./test.db")
SECRET_KEY = config("SECRET_KEY", default="")

1. To use different configurations for staging and production, you can use different .env files for each environment and load the appropriate file depending on the current environment. For example:

# .env.staging
DEBUG=True
DATABASE_URL=postgres://staging_user:staging_password@staging_host:5432/staging_db
SECRET_KEY=mysecretkey

# .env.production
DEBUG=False
DATABASE_URL=postgres://production_user:production_password@production_host:5432/production_db
SECRET_KEY=mysecretkey

1. You can set the environment using an environment variable, for example in your shell or in your .bashrc or .bash_profile:

export ENVIRONMENT=production

1. Then in the code you can use that environment variable to choose which .env file you want to load

from decouple import Config, RepositoryEnv

environment = os.getenv("ENVIRONMENT", "development")
config = Config(RepositoryEnv(f".env.{environment}"))

By using this method, you can easily switch between your staging and production configurations by just changing the environment variable, and keep the sensitive data such as database credentials and secret key away from version control system.

1. Another way to use different configurations for different environment is to use different .env files for each environment and load the appropriate file depending on the current environment. For example, you can have a .env.development file for development environment, a .env.staging file for staging environment and a .env.production file for production environment. In each file, you can have the appropriate configurations for each environment.
2. Then in your main script, you can use the os.environ or os.getenv method to check the current environment and load the corresponding .env file. For example:

import os
from decouple import config

environment = os.getenv("ENVIRONMENT", "development")
if environment == "development":
    config.config_file = ".env.development"
elif environment == "staging":
    config.config_file = ".env.staging"
else:
    config.config_file = ".env.production"

Here, we check the ENVIRONMENT environment variable, if it's not set, it will fall back to "development", otherwise it will use the value of that variable to load the correct .env file.

1. You can also use a environment variable to set the .env file and call it in main script.

export APP_SETTINGS=config.DevelopmentConfig

import os
from decouple import config

config_name = os.getenv("APP_SETTINGS")
app.config.from_object(config_name)

You can use any of the above method to separate your staging and production configurations, depending on your specific use case and requirements. But, either way, decouple library makes it easy to manage your configurations and keep sensitive information, such as secrets and credentials, separate from your codebase, making it more secure and maintainable.