config: set ALLOWED_HOSTS via an environment variable

Author: igneus

gregoplus/settings.py

@@ -28,7 +28,8 @@
 # SECURITY WARNING: don't run with debug turned on in production!
 DEBUG = (os.environ.get('DEBUG') == 'true')
 
-ALLOWED_HOSTS = []
+hosts = os.environ.get('ALLOWED_HOSTS')
+ALLOWED_HOSTS = hosts.split(' ') if hosts else []
 
 
 # Application definition