Usa valores padrão se estiver em branco

project_name/settings.py

@@ -27,12 +27,12 @@ PROJECT_ROOT = os.path.dirname(os.path.abspath(__file__))
 # See https://docs.djangoproject.com/en/1.9/howto/deployment/checklist/
 # SECURITY WARNING: keep the secret key used in production secret!
-SECRET_KEY = os.environ.get('SECRET_KEY', '{{ secret_key }}')
+SECRET_KEY = os.environ.get('SECRET_KEY') or '{{ secret_key }}'
 # SECURITY WARNING: don't run with debug turned on in production!
 DEBUG = get_env_bool('DEBUG')
-ALLOWED_HOSTS = os.environ.get('ALLOWED_HOSTS', '').split(':')
+ALLOWED_HOSTS = [host for host in os.environ.get('ALLOWED_HOSTS', '').split(':') if host] or ['*']
 # Honor the 'X-Forwarded-Proto' header for request.is_secure()
 SECURE_PROXY_SSL_HEADER = ('HTTP_X_FORWARDED_PROTO', 'https')