Enable strategy parameters

Strategy provides parameters to customize algorithm behavior. End user
could query then specify parameters for their requirements.

Change-Id: Id097db5f6e79c94b57674c8e5d55b06098abf18c
Implements-bp: optimization-threshold

watcher/decision_engine/strategy/context/default.py

@@ -16,6 +16,7 @@
 from oslo_log import log
 
 from watcher.common import clients
+from watcher.common import utils
 from watcher.decision_engine.strategy.context import base
 from watcher.decision_engine.strategy.selection import default
 
@@ -58,4 +59,14 @@ class DefaultStrategyContext(base.BaseStrategyContext):
 
         selected_strategy = strategy_selector.select()
 
+        schema = selected_strategy.get_schema()
+        if not audit.parameters and schema:
+            # Default value feedback if no predefined strategy
+            utils.DefaultValidatingDraft4Validator(schema).validate(
+                audit.parameters)
+
+        selected_strategy.input_parameters.update({
+            name: value for name, value in audit.parameters.items()
+        })
+
         return selected_strategy.execute()