Benefits of environment variables

  • Easy configuration
  • Better security
  • Fewer production mistakes

    Question: Does it matter the value of ‘USE_PROD_DB’ is capitalised? SO Answer

It does not make any difference, because when you use os.environ.get() you will get a string, rather than a boolean value, you can consider using django environ instead to parse boolean value directly from environment variable.

Where should env var live

If setting a permanent environment variable:

For system-wide operations, it should be in /etc/profile
For user based operations, it should be in ~/.bash_profile
For non-login interactive shells, it should be in ~/.bashrc
For better understanding, you better check out this: Unix Introduction — Shell

Usage

  • Use environment variables to set which DATABASE to apply locally and on server, 3 steps:

    1. Installation - django-dotenv: 
       (venv)$ pip install django-dotenv
    2. setting up django-dotenv:
      • manage.py and wsgi.py(same dir as settings.py) 
          from dotenv import load_dotenv
  # note that this should be the folder path to your project foler on server
  project_folder = os.path.expanduser('~/myproject')
  load_dotenv(os.path.join(project_folder, '.env'))

        In manage.py, the code above should live inside of main() function

      • In settings.py: 
          # if running locally (No 'USE_PROD_DB' env var got)
  if not os.environ.get('USE_PROD_DB', None):
      DATABASES = {
          'default': {
              'ENGINE': 'django.db.backends.sqlite3',
              'NAME': os.path.join(BASE_DIR, 'db.sqlite3'),
          }
      }
  # if running on server
  else:
      DATABASES = {
          'default': {
              'ENGINE': 'django.db.backends.postgresql_psycopg2',
              'NAME': 'db_name',
              'USER': 'db_user',
              'PASSWORD': 'db_password',
              'HOST': 'localhost',
              'PORT': '',
          }
      }
    3. On server: create a .env file under the same folder as manage.py 
       user@ip_name:~/myproject$ echo 'export USE_PROD_DB=true' > .env

      This should create a file called .env under the correct foler. Django will load this file, and the variables defined in this file will be and only be exported into current OS environment. Therefore, settings.py can catch the variable by running os.environ.get() or os.getenv().

So after these 3 steps, you can simply add a conditional statement in your python files to determine where some certain codes are running.

  • add passwords in .env file

    For security purposes, exporting password in .env file and load them in wherever they need from os (by calling os.environ.get('VAR') or os.getenv('VAR')) would be a good idea in production.