Introduce 'changed_when' keyword to override a task's changed status with the evaluation of a Jinja2 expression

lib/ansible/playbook/__init__.py

@@ -351,7 +351,7 @@ class PlayBook(object):
             # extra vars need to always trump - so update  again following the facts
             self.SETUP_CACHE[host].update(self.extra_vars)
             if task.register:
-                if 'stdout' in result:
+                if 'stdout' in result and 'stdout_lines' not in result:
                     result['stdout_lines'] = result['stdout'].splitlines()
                 self.SETUP_CACHE[host][task.register] = result
 
@@ -359,7 +359,7 @@ class PlayBook(object):
         if task.ignore_errors and task.register:
             failed = results.get('failed', {})
             for host, result in failed.iteritems():
-                if 'stdout' in result:
+                if 'stdout' in result and 'stdout_lines' not in result:
                     result['stdout_lines'] = result['stdout'].splitlines()
                 self.SETUP_CACHE[host][task.register] = result
 

lib/ansible/playbook/task.py

@@ -29,7 +29,7 @@ class Task(object):
         'delegate_to', 'first_available_file', 'ignore_errors',
         'local_action', 'transport', 'sudo', 'sudo_user', 'sudo_pass',
         'items_lookup_plugin', 'items_lookup_terms', 'environment', 'args',
-        'any_errors_fatal'
+        'any_errors_fatal', 'changed_when'
     ]
 
     # to prevent typos and such
@@ -38,7 +38,7 @@ class Task(object):
          'first_available_file', 'include', 'tags', 'register', 'ignore_errors',
          'delegate_to', 'local_action', 'transport', 'sudo', 'sudo_user',
          'sudo_pass', 'when', 'connection', 'environment', 'args',
-         'any_errors_fatal'
+         'any_errors_fatal', 'changed_when'
     ]
 
     def __init__(self, play, ds, module_vars=None, additional_conditions=None):
@@ -88,8 +88,8 @@ class Task(object):
                 else:
                     raise errors.AnsibleError("cannot find lookup plugin named %s for usage in with_%s" % (plugin_name, plugin_name))
 
-            elif x == 'when':
+            elif x in [ 'changed_when', 'when']:
-                ds['when'] = "jinja2_compare %s" % (ds[x])
+                ds[x] = "jinja2_compare %s" % (ds[x])
             elif x.startswith("when_"):
                 if 'when' in ds:
                     raise errors.AnsibleError("multiple when_* statements specified in task %s" % (ds.get('name', ds['action'])))
@@ -161,6 +161,10 @@ class Task(object):
         # load various attributes
         self.only_if = ds.get('only_if', 'True')
         self.when    = ds.get('when', None)
+        self.changed_when = ds.get('changed_when', None)
+
+        if self.changed_when is not None:
+            self.changed_when = utils.compile_when_to_only_if(self.changed_when)
 
         self.async_seconds = int(ds.get('async', 0))  # not async by default
         self.async_poll_interval = int(ds.get('poll', 10))  # default poll = 10 seconds
@@ -214,6 +218,8 @@ class Task(object):
 
         # make ignore_errors accessable to Runner code
         self.module_vars['ignore_errors'] = self.ignore_errors
+        self.module_vars['register'] = self.register
+        self.module_vars['changed_when'] = self.changed_when
 
         # tags allow certain parts of a playbook to be run without running the whole playbook
         apply_tags = ds.get('tags', None)

lib/ansible/runner/__init__.py

@@ -630,6 +630,16 @@ class Runner(object):
                 module_name=module_name
             )
 
+            changed_when = self.module_vars.get('changed_when')
+            if changed_when is not None:
+                register = self.module_vars.get('register')
+                if  register is not None:
+                    if 'stdout' in data:
+                        data['stdout_lines'] = data['stdout'].splitlines()
+                    inject[register] = data
+                changed = template.template(self.basedir, changed_when, inject, fail_on_undefined=self.error_on_undefined_vars)
+                data['changed'] = utils.check_conditional(changed)
+
             if is_chained:
                 # no callbacks
                 return result

test/TestPlayBook.py

@@ -382,6 +382,34 @@ class TestPlaybook(unittest.TestCase):
 
        assert utils.jsonify(expected, format=True) == utils.jsonify(actual,format=True)
 
+   def test_playbook_changed_when(self):
+       test_callbacks = TestCallbacks()
+       playbook = ansible.playbook.PlayBook(
+           playbook=os.path.join(self.test_dir, 'playbook-changed_when.yml'),
+           host_list='test/ansible_hosts',
+           stats=ans_callbacks.AggregateStats(),
+           callbacks=test_callbacks,
+           runner_callbacks=test_callbacks
+       )
+       actual = playbook.run()
+
+       # if different, this will output to screen
+       print "**ACTUAL**"
+       print utils.jsonify(actual, format=True)
+       expected =  {
+           "localhost": {
+               "changed": 3,
+               "failures": 0,
+               "ok": 6,
+               "skipped": 0,
+               "unreachable": 0
+           }
+       }
+       print "**EXPECTED**"
+       print utils.jsonify(expected, format=True)
+
+       assert utils.jsonify(expected, format=True) == utils.jsonify(actual,format=True)
+
    def _compare_file_output(self, filename, expected_lines):
       actual_lines = []
       with open(filename) as f:

test/playbook-changed_when.yml

@@ -0,0 +1,25 @@
+---
+- hosts: all
+  connection: local
+  gather_facts: False
+
+  tasks:
+  - action: command echo first action
+  - action: command echo second action
+    register: var
+    changed_when: "'X' in var.stdout"
+  - action: shell exit 2
+    register: exit
+    ignore_errors: yes
+    changed_when: "exit.rc < 1"
+  - action: command echo third action
+    changed_when: false
+  - action: file path=/ state=directory
+    changed_when: true
+  - action: command echo {{item}}
+    register: out
+    changed_when: "'e' in out.stdout"
+    with_items:
+      - hello
+      - foo
+      - bye