Fix an issue with configs that were None

metaflow/parameters.py

@@ -316,7 +316,7 @@ class MyFlow(FlowSpec):
     help : str, optional, default None
         Help text to show in `run --help`.
     required : bool, optional, default None
-        Require that the user specified a value for the parameter. Note that if
+        Require that the user specifies a value for the parameter. Note that if
         a default is provide, the required flag is ignored.
         A value of None is equivalent to False.
     show_default : bool, optional, default None

metaflow/runner/click_api.py

@@ -371,6 +371,8 @@ def execute(self) -> List[str]:
                     else:
                         components.append(v)
                 for k, v in options.items():
+                    if v is None:
+                        continue
                     if isinstance(v, list):
                         for i in v:
                             if isinstance(i, tuple):

metaflow/user_configs/config_options.py

@@ -169,7 +169,7 @@ def get_config(cls, config_name: str) -> Optional[Dict[Any, Any]]:
                     "Please contact support."
                 )
             cls.loaded_configs = all_configs
-        return cls.loaded_configs.get(config_name, None)
+        return cls.loaded_configs[config_name]
 
     def process_configs(
         self,
@@ -326,6 +326,8 @@ def process_configs(
         for name, val in merged_configs.items():
             if val is None:
                 missing_configs.add(name)
+                to_return[name] = None
+                flow_cls._flow_state[_FlowState.CONFIGS][name] = None
                 continue
             if val.startswith(_CONVERTED_DEFAULT_NO_FILE):
                 no_default_file.append(name)
@@ -339,15 +341,16 @@ def process_configs(
                 val = val[len(_DEFAULT_PREFIX) :]
             if val.startswith("kv."):
                 # This means to load it from a file
-                read_value = self.get_config(val[3:])
-                if read_value is None:
+                try:
+                    read_value = self.get_config(val[3:])
+                except KeyError as e:
                     exc = click.UsageError(
                         "Could not find configuration '%s' in INFO file" % val
                     )
                     if click_obj:
                         click_obj.delayed_config_exception = exc
                         return None
-                    raise exc
+                    raise exc from e
                 flow_cls._flow_state[_FlowState.CONFIGS][name] = read_value
                 to_return[name] = ConfigValue(read_value)
             else:

metaflow/user_configs/config_parameters.py

@@ -290,17 +290,17 @@ class Config(Parameter, collections.abc.Mapping):
     default : Union[str, Callable[[ParameterContext], str], optional, default None
         Default path from where to read this configuration. A function implies that the
         value will be computed using that function.
-        You can only specify default or default_value.
+        You can only specify default or default_value, not both.
     default_value : Union[str, Dict[str, Any], Callable[[ParameterContext, Union[str, Dict[str, Any]]], Any], optional, default None
         Default value for the parameter. A function
         implies that the value will be computed using that function.
-        You can only specify default or default_value.
+        You can only specify default or default_value, not both.
     help : str, optional, default None
         Help text to show in `run --help`.
     required : bool, optional, default None
-        Require that the user specified a value for the configuration. Note that if
-        a default is provided, the required flag is ignored. A value of None is
-        equivalent to False.
+        Require that the user specifies a value for the configuration. Note that if
+        a default or default_value is provided, the required flag is ignored.
+        A value of None is equivalent to False.
     parser : Union[str, Callable[[str], Dict[Any, Any]]], optional, default None
         If a callable, it is a function that can parse the configuration string
         into an arbitrarily nested dictionary. If a string, the string should refer to
@@ -330,13 +330,13 @@ def __init__(
         **kwargs: Dict[str, str]
     ):
 
-        if default and default_value:
+        if default is not None and default_value is not None:
             raise MetaflowException(
                 "For config '%s', you can only specify default or default_value, not both"
                 % name
             )
         self._default_is_file = default is not None
-        kwargs["default"] = default or default_value
+        kwargs["default"] = default if default is not None else default_value
         super(Config, self).__init__(
             name, required=required, help=help, type=str, **kwargs
         )