Parameter deprecation support

This patch adds implementation of parameter deprecation system.
Packstack will now check for deprecated parameters in answer file
if current parameter is not found in answer file.

Also support for default values have been added. Eg. when parameter
is not found in answer file, Packstack tries to use default value
instead of throwing exceptions. This will allow smaller answer files
where only few parameters have to differ from default values.

Change-Id: Id646a442e789221e5c31c9c151bcdfd118652e8f

packstack/installer/run_setup.py

@@ -310,22 +310,53 @@ def _handleGroupCondition(config, conditionName, conditionValue):
     return conditionValue
 
 
-def _loadParamFromFile(config, section, paramName):
+def _loadParamFromFile(config, section, param_name):
     """
     read param from file
     validate it
     and load to to global conf dict
     """
 
-    # Get paramName from answer file
+    param = controller.getParamByName(param_name)
+
+    # Get value from answer file
     try:
-        value = config.get(section, paramName)
+        value = config.get(section, param_name)
     except ConfigParser.NoOptionError:
-        raise KeyError('Parser cannot find option %s in '
-                       'answer file.' % paramName)
+        value = None
+        # Check for deprecated parameters
+        deprecated = param.DEPRECATES if param.DEPRECATES is not None else []
+        for old_name in deprecated:
+            try:
+                val = config.get(section, old_name)
+            except ConfigParser.NoOptionError:
+                continue
+            if not val:
+                # value is empty string
+                continue
+            if value is None:
+                value = val
+            if value != val:
+                raise ValueError('Parameter %(param_name)s deprecates '
+                                 'following parameters:\n%(deprecated)s.\n'
+                                 'Please either use parameter %(param_name)s '
+                                 'or use same value for all deprecated '
+                                 'parameters.' % locals())
+        if deprecated and value is not None:
+            controller.MESSAGES.append('Deprecated parameter has been used '
+                                       'in answer file. Please use parameter '
+                                       '%(param_name)s next time. This '
+                                       'parameter deprecates following '
+                                       'parameters: %(deprecated)s.'
+                                       % locals())
+        if value is None:
+            # Let's use default value if we have one
+            value = getattr(param, 'DEFAULT_VALUE', None)
+        if value is None:
+            raise KeyError('Parser cannot find option %s in answer file.'
+                           % param_name)
 
     # Validate param value using its validation func
-    param = controller.getParamByName(paramName)
     value = process_param_value(param, value)
     validate_param_value(param, value)