The config key is api_base, not base_url

ari.py

@@ -7,7 +7,7 @@ def ari_call(config, verbs, method, payload):
     Return the result.json().
     '''
     try:
-        base_url = config['protocol'] + '://' + config['server'] + '/' + config['base_url']
+        base_url = config['protocol'] + '://' + config['server'] + '/' + config['api_base']
     except KeyError as e:
         raise e
     try: