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,
+        parser = utils.base_parser(
-            output_opts=True, connect_opts=True, check_opts=True, usage='%prog <host-pattern> [options]')
+            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, 
+    parser = utils.base_parser(
-        runas_opts=True, subset_opts=True, check_opts=True)
+        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:

lib/ansible/callbacks.py

@@ -1,4 +1,4 @@
-# (C) 2012, Michael DeHaan, <michael.dehaan@gmail.com>
+# (C) 2012-2013, Michael DeHaan, <michael.dehaan@gmail.com>
 
 # This file is part of Ansible
 #
@@ -35,6 +35,15 @@ elif os.path.exists("/usr/local/bin/cowsay"):
     # BSD path for cowsay
     cowsay = "/usr/local/bin/cowsay"
 
+
+# ****************************************************************************
+# 1.1 DEV NOTES
+# FIXME -- in order to make an ideal callback system, all of these should have
+# access to the current task and/or play and host objects.  We need to this
+# while keeping present callbacks functionally intact and will do so.
+# ****************************************************************************
+
+
 def call_callback_module(method_name, *args, **kwargs):
 
     for callback_plugin in utils.plugins.callback_loader.all():
@@ -209,6 +218,9 @@ class DefaultRunnerCallbacks(object):
     def on_async_failed(self, host, res, jid):
         call_callback_module('runner_on_async_failed', host, res, jid)
 
+    def on_file_diff(self, host, before_string, after_string):
+        call_callback_module('runner_on_file_diff', before_string, after_string)
+
 ########################################################################
 
 class CliRunnerCallbacks(DefaultRunnerCallbacks):
@@ -272,6 +284,11 @@ class CliRunnerCallbacks(DefaultRunnerCallbacks):
         print host_report_msg(host, self.options.module_name, result2, self.options.one_line)
         if self.options.tree:
             utils.write_tree_file(self.options.tree, host, utils.jsonify(result2,format=True))
+    
+    def on_file_diff(self, host, before_string, after_string):
+        if self.options.diff:
+            print utils.get_diff(before_string, after_string)
+        super(CliRunnerCallbacks, self).on_file_diff(host, before_string, after_string)
 
 ########################################################################
 
@@ -404,6 +421,9 @@ class PlaybookRunnerCallbacks(DefaultRunnerCallbacks):
         print stringc(msg, 'red')
         super(PlaybookRunnerCallbacks, self).on_async_failed(host,res,jid)
 
+    def on_file_diff(self, host, before_string, after_string):
+        print utils.get_diff(before_string, after_string)
+        super(PlaybookRunnerCallbacks, self).on_file_diff(host, before_string, after_string)
 
 ########################################################################
 

lib/ansible/playbook/__init__.py

@@ -62,7 +62,8 @@ class PlayBook(object):
         only_tags        = None,
         subset           = C.DEFAULT_SUBSET,
         inventory        = None,
-        check            = False):
+        check            = False,
+        diff             = False):
 
         """
         playbook:         path to a playbook file
@@ -94,6 +95,7 @@ class PlayBook(object):
             only_tags = [ 'all' ]
 
         self.check            = check
+        self.diff             = diff
         self.module_path      = module_path
         self.forks            = forks
         self.timeout          = timeout
@@ -271,7 +273,7 @@ class PlayBook(object):
             conditional=task.only_if, callbacks=self.runner_callbacks,
             sudo=task.sudo, sudo_user=task.sudo_user,
             transport=task.transport, sudo_pass=task.sudo_pass, is_playbook=True,
-            check=self.check
+            check=self.check, diff=self.diff
         )
 
         if task.async_seconds == 0:
@@ -377,7 +379,7 @@ class PlayBook(object):
             remote_pass=self.remote_pass, remote_port=play.remote_port, private_key_file=self.private_key_file,
             setup_cache=self.SETUP_CACHE, callbacks=self.runner_callbacks, sudo=play.sudo, sudo_user=play.sudo_user,
             transport=play.transport, sudo_pass=self.sudo_pass, is_playbook=True, module_vars=play.vars,
-            check=self.check
+            check=self.check, diff=self.diff
         ).run()
         self.stats.compute(setup_results, setup=True)
 

lib/ansible/runner/__init__.py

@@ -118,11 +118,13 @@ class Runner(object):
         is_playbook=False,                  # running from playbook or not?
         inventory=None,                     # reference to Inventory object
         subset=None,                        # subset pattern
-        check=False                         # don't make any changes, just try to probe for potential changes
+        check=False,                        # don't make any changes, just try to probe for potential changes
+        diff=False
         ):
 
         # storage & defaults
         self.check            = check
+        self.diff             = diff
         self.setup_cache      = utils.default(setup_cache, lambda: collections.defaultdict(dict))
         self.basedir          = utils.default(basedir, lambda: os.getcwd())
         self.callbacks        = utils.default(callbacks, lambda: DefaultRunnerCallbacks())
@@ -192,7 +194,7 @@ class Runner(object):
     # *****************************************************
 
     def _execute_module(self, conn, tmp, module_name, args,
-        async_jid=None, async_module=None, async_limit=None, inject=None):
+        async_jid=None, async_module=None, async_limit=None, inject=None, persist_files=False):
 
         ''' runs a module that has already been transferred '''
 
@@ -233,7 +235,7 @@ class Runner(object):
             raise errors.AnsibleError("module is missing interpreter line")
 
         cmd = shebang.replace("#!","") + " " + cmd
-        if tmp.find("tmp") != -1 and C.DEFAULT_KEEP_REMOTE_FILES != '1':
+        if tmp.find("tmp") != -1 and C.DEFAULT_KEEP_REMOTE_FILES != '1' and not persist_files:
             cmd = cmd + "; rm -rf %s >/dev/null 2>&1" % tmp
         res = self._low_level_exec_command(conn, cmd, tmp, sudoable=True)
         data = utils.parse_json(res['stdout'])

lib/ansible/runner/action_plugins/template.py

@@ -20,6 +20,7 @@ import os
 from ansible import utils
 from ansible import errors
 from ansible.runner.return_data import ReturnData
+import base64
 
 class ActionModule(object):
 
@@ -46,6 +47,7 @@ class ActionModule(object):
 
         # if we have first_available_file in our vars
         # look up the files and use the first one we find as src
+
         if 'first_available_file' in inject:
             found = False
             for fn in self.runner.module_vars.get('first_available_file'):
@@ -79,18 +81,35 @@ class ActionModule(object):
 
              # template is different from the remote value
 
-             xfered = self.runner._transfer_str(conn, tmp, 'source', resultant)
+             # if showing diffs, we need to get the remote value
+             dest_contents = None    
+             if self.runner.diff:
+                 # using persist_files to keep the temp directory around to avoid needing to grab another
+                 dest_result = self.runner._execute_module(conn, tmp, 'slurp', "path=%s" % dest, inject=inject, persist_files=True)
+                 dest_contents = dest_result.result['content']
+                 if dest_result.result['encoding'] == 'base64':
+                     dest_contents = base64.b64decode(dest_contents)
+                 else:
+                     raise Exception("unknown encoding, failed: %s" % dest_result.result)
+
+             xfered = self.runner._transfer_str(conn, tmp, source, resultant)
+
              # fix file permissions when the copy is done as a different user
              if self.runner.sudo and self.runner.sudo_user != 'root':
                  self.runner._low_level_exec_command(conn, "chmod a+r %s" % xfered, tmp)
 
              # run the copy module
              module_args = "%s src=%s dest=%s" % (module_args, xfered, dest)
-
+ 
              if self.runner.check:
+                 if self.runner.diff:
+                     self.runner.callbacks.on_file_diff(conn.host, dest_contents, resultant)
                  return ReturnData(conn=conn, comm_ok=True, result=dict(changed=True))
              else:
-                 return self.runner._execute_module(conn, tmp, 'copy', module_args, inject=inject)
+                 res =  self.runner._execute_module(conn, tmp, 'copy', module_args, inject=inject)
+                 if self.runner.diff:
+                     self.runner.callbacks.on_file_diff(conn.host, dest_contents, resultant)
+                 return res
         else:
              return ReturnData(conn=conn, comm_ok=True, result=dict(changed=False))
 

lib/ansible/utils/__init__.py

@@ -34,6 +34,7 @@ import termios
 import tty
 import pipes
 import random
+import difflib
 
 VERBOSITY=0
 
@@ -395,7 +396,7 @@ def increment_debug(option, opt, value, parser):
     VERBOSITY += 1
 
 def base_parser(constants=C, usage="", output_opts=False, runas_opts=False,
-    async_opts=False, connect_opts=False, subset_opts=False, check_opts=False):
+    async_opts=False, connect_opts=False, subset_opts=False, check_opts=False, diff_opts=False):
     ''' create an options parser for any ansible script '''
 
     parser = SortedOptParser(usage, version=version("%prog"))
@@ -457,6 +458,12 @@ def base_parser(constants=C, usage="", output_opts=False, runas_opts=False,
             help="don't make any changes, instead try to predict some of the changes that may occur"
         )
 
+    if diff_opts:
+        parser.add_option("-D", "--diff", default=False, dest='diff', action='store_true',
+            help="when changing (small) files and templates, show the differences in those files, works great with --check"
+        )
+
+
     return parser
 
 def do_encrypt(result, encrypt, salt_size=None, salt=None):
@@ -602,3 +609,10 @@ def make_sudo_cmd(sudo_user, executable, cmd):
         C.DEFAULT_SUDO_EXE, C.DEFAULT_SUDO_EXE, C.DEFAULT_SUDO_FLAGS,
         prompt, sudo_user, executable or '$SHELL', pipes.quote(cmd))
     return ('/bin/sh -c ' + pipes.quote(sudocmd), prompt)
+
+def get_diff(before_string, after_string):
+    # called by --diff usage in playbook and runner via callbacks
+    # include names in diffs 'before' and 'after' and do diff -U 10
+    differ = difflib.unified_diff(before_string.split("\n"), after_string.split("\n"), 'before', 'after', '', '', 10)
+    return "\n".join(list(differ))
+ 

library/slurp

@@ -50,7 +50,7 @@ author: Michael DeHaan
 def main():
     module = AnsibleModule(
         argument_spec = dict(
-            src = dict(required=True),
+            src = dict(required=True, aliases=['path']),
         )
     )
     source = module.params['src']