environmental variables

what is it?

user-definable value that can affect the way running processes will behave on a computer

ways to configure

.env file

convention is to create a dot file, to signify that the file is a hidden/system file

example is environmental variables for a django project with celery and a postgresql database:

.env

DEBUG=1
SECRET_KEY=dbaa1_i7%*3r9-=z-+_mz4r-!qeed@(-a_r(g@k8jo8y3r27%m
DJANGO_ALLOWED_HOSTS=*
 
SQL_ENGINE=django.db.backends.postgresql
SQL_DATABASE=hello_django
SQL_USER=hello_django
SQL_PASSWORD=hello_django
SQL_HOST=db
SQL_PORT=5432
 
CELERY_BROKER=redis://redis:6379/0
CELERY_BACKEND=redis://redis:6379/0

to use the above env vars in django

settings.py

import os
 
# handle boolean env vars like so
DEBUG = int(os.environ.get("DEBUG", False))
 
DATABASES = {
    "default": {
        "ENGINE": os.environ.get("SQL_ENGINE", "django.db.backends.sqlite3"),
        "NAME": os.environ.get("SQL_DATABASE", os.path.join(BASE_DIR, "db.sqlite3")),
        "USER": os.environ.get("SQL_USER", "user"),
        "PASSWORD": os.environ.get("SQL_PASSWORD", "password"),
        "HOST": os.environ.get("SQL_HOST", "localhost"),
        "PORT": os.environ.get("SQL_PORT", "5432"),
    }
}
 
CELERY_BROKER_URL = os.environ.get("CELERY_BROKER", "redis://127.0.0.1:6379/0")
CELERY_RESULT_BACKEND = os.environ.get("CELERY_BACKEND", "redis://127.0.0.1:6379/0")