Add ability to store and access module results later on in the play. See…

Add ability to store and access module results later on in the play.  See examples/playbooks/register_logic for details.

CHANGELOG.md

@@ -27,7 +27,7 @@ Ansible Changes By Release
 * allow variables in parameterized task include parameters (regression)
 * make remote_md5 internal function work with non-bash shells
 * allow user to be passed in via --extra-vars (regression)
-* ${last_result} variable stores the last result for each host
+* add ability to store the result of any command in a register (see examples/playbooks/register_logic.yml)
 
 0.6 "Cabo" -- August 6, 2012
 

examples/playbooks/register_logic.yml

+# here's a cool advanced topic about how to perform conditional logic in ansible without resorting
+# to writing your own module that defines facts.  You can do that too, and it's easy to do, but
+# often you just want to run a command and then decide whether to run some steps or not.  That's
+# easy to do, and here we'll show you how.
+
+- name: test playbook
+  user: root
+  hosts: all
+
+  tasks:
+
+      # it is possible to save the result of any command in a named register.  This variable will be made
+      # available to tasks and templates made further down in the execution flow.  Here we save the result
+      # of a simple 'cat' command in a variable called 'motd_contents'
+
+      - action: shell cat /etc/motd
+        register: motd_contents
+
+      # and here we access the register.  Note that motd_contents as a variable is structured data because
+      # it is a return from the command module.   The shell module makes available variables such as
+      # as 'stdout', 'stderr', and 'rc'.  Here's a rather trivial example that runs an arbitrary step
+      # if and only if the motd file contained the word 'hi'.   Remember that only_if statements are
+      # Python expressions.  This is as complicated as Ansible syntax is going to get, and the only
+      # time python really seeps into ansible's language.
+ 
+      - action: shell echo "motd contains the word hi"
+        only_if: "'${motd_contents.stdout}'.find('hi') != -1"
+
+

lib/ansible/playbook/__init__.py

@@ -224,7 +224,8 @@ class PlayBook(object):
         for host, result in results['contacted'].iteritems():
             facts = result.get('ansible_facts', {})
             self.SETUP_CACHE[host].update(facts)
-            self.SETUP_CACHE[host]['last_result'] = result
+            if task.register:
+                self.SETUP_CACHE[host][task.register] = result
 
         # flag which notify handlers need to be run
         if len(task.notify) > 0:

lib/ansible/playbook/task.py

@@ -23,13 +23,13 @@ class Task(object):
     __slots__ = [
         'name', 'action', 'only_if', 'async_seconds', 'async_poll_interval',
         'notify', 'module_name', 'module_args', 'module_vars',
-        'play', 'notified_by', 'tags', 'with_items', 'first_available_file', 'ignore_errors'
+        'play', 'notified_by', 'tags', 'register', 'with_items', 'first_available_file', 'ignore_errors'
     ]
 
     # to prevent typos and such
     VALID_KEYS = [
          'name', 'action', 'only_if', 'async', 'poll', 'notify', 'with_items', 'first_available_file',
-         'include', 'tags', 'ignore_errors'
+         'include', 'tags', 'register', 'ignore_errors'
     ]
 
     def __init__(self, play, ds, module_vars=None):
@@ -46,6 +46,7 @@ class Task(object):
         self.name        = ds.get('name', None)
         self.action      = ds.get('action', '')
         self.tags        = [ 'all' ]
+        self.register    = ds.get('register', None)
 
         # notified by is used by Playbook code to flag which hosts
         # need to run a notifier