[Python] Usage of .env

.env file is commonly used for configuration.

Python also has 3rd party library for this.

Installation

It can be installed by pip.

$ pip install python-dotenv

Create .env File

.env file consists of key-value pair.

# .env

TEST=test
TEST_URL=${TEST}.com

You can expand the config using ${} syntax.

TEST1="test
string"

TEST2="Test\nString"

You can use a value as multiple lines using escape characters and quotes.

It is also possible to use other escape characters like \t, \r, \\, \', \", etc.

Using with load_dotenv

python-dotenv module has load_dotenv() function.

This function registers the configuration into environment variables.

import os
from dotenv import load_dotenv

load_dotenv()

print(os.environ['TEST'])
# test
print(os.environ['TEST_URL'])
# test.com

load_dotenv() function has override parameter and its default value is True.

load_dotenv(override=True)

It means overriding system environment variables if the same configuration exists.

In other words, if you set this to False, system environment variables are used if the same configuration exists.

Using with dotenv_values

dotenv_values() function returns ordered dictionary with configuration.

import os
from dotenv import dotenv_values

config = dotenv_values('.env')

print(config['TEST'])
# test
print(config['TEST_URL'])
# test.com