Environment variables

Environment variables are variables that store data in your program but outside your code. For example, key and secret for an API.

I want this information to be stored outside my source code, so I can keep sensitive data safe. I don't want to expose my credentials inside my open-source code. In addition, I don’t want to touch my code each time API credentials have changed.

I can access already set environment variables like “USER” for example, using os.environ["USER"] or os.environ.get("USER"), I can add my own environment variable like: os.environ['API_USER'] = 'username'

Cool for now

When I create a new environment variable, it only exists for that session. When I close the terminal/program, the environment variable no longer exists. How can I make these variables persist?

Persistence

My preferred way is to use python-dotenv library

First install the library

pip3 install python-dotenv        

then create a .env file in the same directory as the Python file resides.

Next, create a variable inside .env file like this: Name = "value"

Back into the code, I will import the library

from dotenv import load_dotenv        

calling load_dotenv function, brings environment variables into os.environ, and now I can access them.

print(os.environ["API_USER"])        

Cool for now

What if I have two environments, each has its own keys. How can I verify Production environment is using Production keys and Development environment is using Development keys?

I can specify more than one .env file, and direct load_dotenv to locate the correct .env file.

For example:

home = Path().absolute(


dev_path = Path(f'{home}/DEV/.env')


prod_path = Path(f'{home}/PROD/.env'))        

when I want to load the Development environment keys, I will use

load_dotenv(dotenv_path=dev_path)        

and when I want to load the Production environment keys, I will use

load_dotenv(dotenv_path=prod_path)        

By default, load_dotenv doesn't override existing environment variables, so in case I have two different environments, either I can use different keys

Or in case I want to use the same key in both .env files, I will need to call load_dotenv with override=True to allow overriding the environment value