framework/configruation: fix mandatory workload parameters

PluginCache.get_plugin_config assumes that no more configuration is to
be processed, and therefore config is final. As such, it is validating
that mandatory parameters are set. This assumption is invalid for
workload_parameters, however, as those need to be resolved on per-spec
basis, and cannot be globally cached.

This commit adds a prameter for get_plugin_config that indicates whether
or not it should consider the config to be final.

wa/framework/configuration/core.py

@@ -272,12 +272,12 @@ class ConfigurationPoint(object):
             value = merge_config_values(getattr(obj, self.name), value)
         setattr(obj, self.name, value)
 
-    def validate(self, obj):
+    def validate(self, obj, check_mandatory=True):
         value = getattr(obj, self.name, None)
         if value is not None:
             self.validate_value(obj.name, value)
         else:
-            if self.mandatory:
+            if check_mandatory and self.mandatory:
                 msg = 'No value specified for mandatory parameter "{}" in {}.'
                 raise ConfigError(msg.format(self.name, obj.name))
 
@@ -928,7 +928,8 @@ class JobSpec(Configuration):
     def merge_workload_parameters(self, plugin_cache):
         # merge global generic and specific config
         workload_params = plugin_cache.get_plugin_config(self.workload_name,
-                                                         generic_name="workload_parameters")
+                                                         generic_name="workload_parameters",
+                                                         is_final=False)
 
         cfg_points = plugin_cache.get_plugin_parameters(self.workload_name)
         for source in self._sources:

wa/framework/configuration/plugin_cache.py

@@ -99,7 +99,7 @@ class PluginCache(object):
     def list_plugins(self, kind=None):
         return self.loader.list_plugins(kind)
 
-    def get_plugin_config(self, plugin_name, generic_name=None):
+    def get_plugin_config(self, plugin_name, generic_name=None, is_final=True):
         config = obj_dict(not_in_dict=['name'])
         config.name = plugin_name
 
@@ -120,7 +120,8 @@ class PluginCache(object):
         else:
             # A more complicated merge that involves priority of sources and
             # specificity
-            self._merge_using_priority_specificity(plugin_name, generic_name, config)
+            self._merge_using_priority_specificity(plugin_name, generic_name,
+                                                   config, is_final)
 
         return config
 
@@ -158,7 +159,7 @@ class PluginCache(object):
 
     # pylint: disable=too-many-nested-blocks, too-many-branches
     def _merge_using_priority_specificity(self, specific_name, 
-                                          generic_name, final_config):
+                                          generic_name, merged_config, is_final=True):
         """
         WA configuration can come from various sources of increasing priority,
         as well as being specified in a generic and specific manner (e.g
@@ -175,13 +176,15 @@ class PluginCache(object):
         In this situation it is not possible to know the end users intention
         and WA will error.
 
-        :param generic_name: The name of the generic configuration
-                             e.g ``device_config``
         :param specific_name: The name of the specific configuration used
                               e.g ``nexus10``
-        :param cfg_point: A dict of ``ConfigurationPoint``s to be used when
-                          merging configuration.  keys=config point name, 
-                          values=config point
+        :param generic_name: The name of the generic configuration
+                             e.g ``device_config``
+        :param merge_config: A dict of ``ConfigurationPoint``s to be used when
+                             merging configuration.  keys=config point name, 
+                             values=config point
+        :param is_final: if ``True`` (the default) make sure that mandatory
+                         parameters are set.
 
         :rtype: A fully merged and validated configuration in the form of a
                 obj_dict.
@@ -197,18 +200,18 @@ class PluginCache(object):
         # set_value uses the 'name' attribute of the passed object in it error
         # messages, to ensure these messages make sense the name will have to be
         # changed several times during this function.
-        final_config.name = specific_name
+        merged_config.name = specific_name
 
         for source in sources:
             try:
-                update_config_from_source(final_config, source, ms)
+                update_config_from_source(merged_config, source, ms)
             except ConfigError as e:
                 raise ConfigError('Error in "{}":\n\t{}'.format(source, str(e)))
 
         # Validate final configuration
-        final_config.name = specific_name
+        merged_config.name = specific_name
         for cfg_point in ms.cfg_points.itervalues():
-            cfg_point.validate(final_config)
+            cfg_point.validate(merged_config, check_mandatory=is_final)
 
 
 class MergeState(object):