fix problem when no configuration parameters are set

execution/lib/cli_parser.py

 import argparse
 import os
 
+
 def env_list_default(env, tf):
     """
     Makes a list from an environment string.
@@ -17,7 +18,7 @@ def key_values_to_dict(kvs):
     """
     my_dict = {}
     for kv in kvs:
-        k,v = kv.split("=")
+        k, v = kv.split("=")
         my_dict[k] = v
     return my_dict
 
@@ -29,15 +30,19 @@ def env_dict_default(env):
     v = os.environ.get(env)
     if v is not None:
         return key_values_to_dict(v.split(','))
+    else:
+        return dict()
 
 
 class StoreDictKeyPair(argparse.Action):
-     def __init__(self, option_strings, dest, nargs=None, **kwargs):
-         self._nargs = nargs
-         super(StoreDictKeyPair, self).__init__(option_strings, dest, nargs=nargs, **kwargs)
-     def __call__(self, parser, namespace, values, option_string=None):
-         my_dict = key_values_to_dict(values)
-         setattr(namespace, self.dest, my_dict)
+    def __init__(self, option_strings, dest, nargs=None, **kwargs):
+        self._nargs = nargs
+        super(StoreDictKeyPair, self).__init__(
+            option_strings, dest, nargs=nargs, **kwargs)
+
+    def __call__(self, parser, namespace, values, option_string=None):
+        my_dict = key_values_to_dict(values)
+        setattr(namespace, self.dest, my_dict)
 
 
 def default_parser(description):
@@ -81,7 +86,8 @@ def default_parser(description):
                         help='Only resets the environment. Ignores all other parameters')
     parser.add_argument('--prometheus',
                         metavar='<URL>',
-                        default=os.environ.get('PROMETHEUS_BASE_URL', 'http://localhost:9090'),
+                        default=os.environ.get(
+                            'PROMETHEUS_BASE_URL', 'http://localhost:9090'),
                         help='Defines where to find the prometheus instance')
     parser.add_argument('--path',
                         metavar='<path>',
@@ -96,6 +102,7 @@ def default_parser(description):
                         help='Defines the environment variables for the UC')
     return parser
 
+
 def benchmark_parser(description):
     """
     Parser for the overall benchmark execution
@@ -125,6 +132,7 @@ def benchmark_parser(description):
                         help='The benchmarking search strategy. Can be set to default, linear-search or binary-search')
     return parser
 
+
 def execution_parser(description):
     """
     Parser for executing one use case