old_contents: import os
  
  from .base import BASE_DIR
  
  
  # Database
  # https://docs.djangoproject.com/en/1.9/ref/settings/#databases
  
  DATABASES = {
      'default': {
          'ENGINE': 'django.db.backends.sqlite3',
          'NAME': os.path.join(BASE_DIR, 'db.sqlite3'),
      }
  }
  
new_contents: import os
  
  import dj_database_url
  
  from .base import BASE_DIR
  
  
  # Database
  # https://docs.djangoproject.com/en/1.9/ref/settings/#databases
  
  # dj-database-url
  # https://github.com/kennethreitz/dj-database-url
  
  DATABASES = {}
  DATABASES['default'] = dj_database_url.config(
      default=os.environ.get("DATABASE_URL"),
  )
  
  # DATABASES = {
  #     'default': {
  #         'ENGINE': 'django.db.backends.sqlite3',
  #         'NAME': os.path.join(BASE_DIR, 'db.sqlite3'),
  #     }
  # }
  
subject: update database settings: change database url to environment variable