Very basic --diff option for showing what happens when templates change.

Probably output is not useful if not used with --limit

Works well with --check mode

bin/ansible

@@ -45,8 +45,18 @@ class Cli(object):
     def parse(self):
         ''' create an options parser for bin/ansible '''
 
-        parser = utils.base_parser(constants=C, runas_opts=True, subset_opts=True, async_opts=True,
-            output_opts=True, connect_opts=True, check_opts=True, usage='%prog <host-pattern> [options]')
+        parser = utils.base_parser(
+            constants=C, 
+            runas_opts=True, 
+            subset_opts=True, 
+            async_opts=True,
+            output_opts=True, 
+            connect_opts=True, 
+            check_opts=True,
+            diff_opts=False,
+            usage='%prog <host-pattern> [options]'
+        )
+
         parser.add_option('-a', '--args', dest='module_args',
             help="module arguments", default=C.DEFAULT_MODULE_ARGS)
         parser.add_option('-m', '--module-name', dest='module_name',
@@ -54,6 +64,7 @@ class Cli(object):
             default=C.DEFAULT_MODULE_NAME)
         parser.add_option('--list-hosts', dest='listhosts', action='store_true',
             help="dump out a list of hosts matching input pattern, does not execute any modules!")
+
         options, args = parser.parse_args()
         self.callbacks.options = options
 
@@ -112,7 +123,8 @@ class Cli(object):
             callbacks=self.callbacks, sudo=options.sudo,
             sudo_pass=sudopass,sudo_user=options.sudo_user,
             transport=options.connection, subset=options.subset,
-            check=options.check
+            check=options.check,
+            diff=options.check
         )
 
         if options.seconds:

bin/ansible-playbook

@@ -52,8 +52,15 @@ def main(args):
 
     # create parser for CLI options
     usage = "%prog playbook.yml"
-    parser = utils.base_parser(constants=C, usage=usage, connect_opts=True, 
-        runas_opts=True, subset_opts=True, check_opts=True)
+    parser = utils.base_parser(
+        constants=C, 
+        usage=usage, 
+        connect_opts=True, 
+        runas_opts=True, 
+        subset_opts=True, 
+        check_opts=True,
+        diff_opts=True
+    )
     parser.add_option('-e', '--extra-vars', dest="extra_vars", default=None,
         help="set additional key=value variables from the CLI")
     parser.add_option('-t', '--tags', dest='tags', default='all',
@@ -122,7 +129,8 @@ def main(args):
             extra_vars=extra_vars,
             private_key_file=options.private_key_file,
             only_tags=only_tags,
-            check=options.check
+            check=options.check,
+            diff=options.diff
         )
         
         if options.listhosts: