changes to not clear the setup cache between runs, and also decide to run plays with no tasks

in them if it looks like they are not tagged, because if that is the case, then we may just
be gathering facts about them.

lib/ansible/playbook/__init__.py

@@ -24,6 +24,8 @@ import os
 import collections
 from play import Play
 
+SETUP_CACHE = collections.defaultdict(dict)
+
 class PlayBook(object):
     '''
     runs an ansible playbook, given as a datastructure or YAML filename.  
@@ -75,7 +77,7 @@ class PlayBook(object):
         sudo:             if not specified per play, requests all plays use sudo mode
         """
 
-        self.SETUP_CACHE = collections.defaultdict(dict)
+        self.SETUP_CACHE = SETUP_CACHE
 
         if playbook is None or callbacks is None or runner_callbacks is None or stats is None:
             raise Exception('missing required arguments')
@@ -148,7 +150,6 @@ class PlayBook(object):
         # loop through all patterns and run them
         self.callbacks.on_start()
         for play_ds in self.playbook:
-            self.SETUP_CACHE = collections.defaultdict(dict)
             self._run_play(Play(self,play_ds))
 
         # summarize the results
@@ -219,11 +220,6 @@ class PlayBook(object):
         if results is None:
             results = {}
 
-        # add facts to the global setup cache
-        for host, result in results['contacted'].iteritems():
-            facts = result.get('ansible_facts', {})
-            self.SETUP_CACHE[host].update(facts)
-
         self.stats.compute(results)
  
         # flag which notify handlers need to be run

lib/ansible/playbook/play.py

@@ -178,15 +178,20 @@ class Play(object):
     def should_run(self, tags):
         ''' does the play match any of the tags? '''
 
-        if len(self._tasks) == 0:
-            return False
-
+        tags_counted = 0
         for task in self._tasks:
             for task_tag in task.tags:
+                tags_counted = tags_counted + 1
                 if task_tag in tags:
                     return True
+
+        if tags_counted > 0:
             return False  
    
+        # didn't tag the play, and the play contains no steps
+        # so assume we just want to gather facts
+        return True                  
+
     # *************************************************
 
     def _has_vars_in(self, msg):