Notifable handlers only run when something is changed. Awesome.

TODO.md

-TODO list and plans
-===================
-
-Playbook TODO:
-
-   * error codes and failure summaries
-   * handle 'changed' attributes
-   * fail nodes on errors, i.e. remove from host list, rather than continuing to pound them
-   * further improve output
-   * more conditional capability (if statement) (?)
-   * very good logging
-
-Command module:
-   * magic to pull async & timeout options off of the command line and not feed them
-     to the app we're executing
- 
-General:
-
-   * better logging
-   * async options
-   * modules for users, groups, and files, using puppet style ensure mechanics
-   * think about how to build idempotency (aka Puppet-style 'creates') around command module?
-
-Bonus utilities:
-
-   * ansible-inventory - gathering fact/hw info, storing in git, adding RSS
-   * ansible-slurp - recursively rsync file trees for each host
-   * maybe it's own fact engine, not required, that also feeds from facter
-
-Not so interested really, but maybe:
-
-   * list available modules from command line
-   * add/remove/list hosts from the command line
-   * filter exclusion (run this only if fact is true/false)
-     -- should be doable with playbooks (i.e. not neccessary)
-

examples/playbook.yml

@@ -6,17 +6,18 @@
   - do:
     - copy a file
     - copy /srv/a /srv/b
+    notify: 
+    - restart apache
   - do:
     - template from local file template.j2 to remote location /srv/file.out
     - template /srv/template.j2 /srv/file.out
-  - do:
-    - update apache
-    - command /usr/bin/yum update apache
-    onchange:
+    notify:
+    - restart apache
+    - quack like a duck
+  handlers:
     - do:
       - restart apache
-      - command /sbin/service apache restart
+      - command /sbin/service httpd restart
     - do:
-      - run bin false
-      - command /bin/false
-
+      - quack like a duck
+      - command /bin/true

lib/ansible/playbook.py

@@ -101,7 +101,7 @@ class PlayBook(object):
             timeout=self.timeout
         )
 
-    def _run_task(self, pattern, task, host_list=None, conditional=False):
+    def _run_task(self, pattern=None, task=None, host_list=None, handlers=None, conditional=False):
         ''' 
         run a single task in the playbook and
         recursively run any subtasks.
@@ -118,7 +118,7 @@ class PlayBook(object):
 
         namestr = "%s/%s" % (pattern, comment)
         if conditional:
-            namestr = "subset/%s" % namestr
+            namestr = "notified/%s" % namestr
         print "TASK [%s]" % namestr
 
         runner = self._get_task_runner(
@@ -130,15 +130,7 @@ class PlayBook(object):
         results = runner.run()
  
         dark = results.get("dark", [])
-        
         contacted = results.get("contacted", [])
-
-        # TODO: filter based on values that indicate
-        # they have changed events to emulate Puppet
-        # 'notify' behavior, super easy -- just
-        # a list comprehension -- but we need complaint
-        # modules first
-
         ok_hosts = contacted.keys()
 
         for host, msg in dark.items():
@@ -152,27 +144,51 @@ class PlayBook(object):
                   print "FAIL: [%s/%s]" % (host, comment, results)
  
 
-        subtasks = task.get('onchange', [])
+        # flag which notify handlers need to be run
+        subtasks = task.get('notify', [])
         if len(subtasks) > 0:
-            for subtask in subtasks:
-                self._run_task(pattern, subtask, ok_hosts, conditional=True)
+            for host, results in contacted.items():
+               if results.get('changed', False):
+                  for subtask in subtasks:
+                      self._flag_handler(handlers, subtask, host)
 
-        # TODO: if a host fails in task 1, add it to an excludes
-        # list such that no other tasks in the list ever execute
-        # unlike Puppet, do not allow partial failure of the tree
-        # and continuing as far as possible.  Fail fast.
+        # TODO: if a host fails in any task, remove it from
+        # the host list immediately
 
+    def _flag_handler(self, handlers, match_name, host):
+        ''' 
+        if a task has any notify elements, flag handlers for run
+        at end of execution cycle for hosts that have indicated
+        changes have been made
+        '''
+        for x in handlers:
+            attribs = x["do"]
+            name = attribs[0]
+            if match_name == name:
+               if not x.has_key("run"):
+                  x['run'] = []
+               x['run'].append(host)
 
     def _run_pattern(self, pg):
         '''
         run a list of tasks for a given pattern, in order
         '''
 
-        pattern = pg['pattern']
-        tasks   = pg['tasks']
-        for task in tasks:
-            self._run_task(pattern, task)
+        pattern  = pg['pattern']
+        tasks    = pg['tasks']
+        handlers = pg['handlers']
 
+        for task in tasks:
+            self._run_task(pattern=pattern, task=task, handlers=handlers)
+        for task in handlers:
+            if type(task.get("run", None)) == list:
+                self._run_task(
+                   pattern=pattern, 
+                   task=task, 
+                   handlers=handlers,
+                   host_list=task.get('run',[]),
+                   conditional=True
+                )