log a warning when we get no params from SSM for a given prefix

dj_secure_settings/loader.py

@@ -103,15 +103,20 @@ def _load_params_from_ssm(config, path_prefix, region_name=None):
             ssm = boto3.client("ssm", region_name=region_name)
     args = {"Path": path_prefix, "Recursive": True, "WithDecryption": True}
     more = None
+    params_found = 0
     while more is not False:
         if more:
             args["NextToken"] = more
         params = ssm.get_parameters_by_path(**args)
         for param in params["Parameters"]:
             keys = param['Name'][len(path_prefix):].split('/')
             _set_nested(config, keys, param['Value'])
+            params_found += 1
         more = params.get("NextToken", False)
 
+    if params_found == 0:
+        logging.warning('Found no SSM parameters for prefix {}'.format(path_prefix))
+
 
 def _set_nested(dic, keys, value):
     # this sets a value in an arbitrarily-deeply nested dict