Plugins are pieces of code that augment Ansible’s core functionality. Ansible ships with a number of handy plugins, and you can easily write your own.
The following types of plugins are available:
This section describes the various types of plugins and how to implement them.
Callback plugins enable adding new behaviors to Ansible when responding to events.
Ansible comes with a number of callback plugins that you can look at for examples. These can be found in lib/ansible/plugins/callback.
The osx_say callback provided is particularly entertaining – it will respond with computer synthesized speech on OS X in relation to playbook events, and is guaranteed to entertain and/or annoy coworkers.
To activate a callback, drop it in a callback directory as configured in ansible.cfg.
Plugins are loaded in alphanumeric order; for example, a plugin implemented in a file named 1_first.py would run before a plugin file named 2_second.py.
Callbacks need to be whitelisted in your ansible.cfg file in order to function. For example:
#callback_whitelist = timer, mail, mycallbackplugin
Callback plugins are created by creating a new class with the Base(Callbacks) class as the parent:
from ansible.plugins.callback import CallbackBase from ansible import constants as C class CallbackModule(CallbackBase):
From there, override the specific methods from the CallbackBase that you want to provide a callback for. For plugins intended for use with Ansible version 2.0 and later, you should only override methods that start with v2. For a complete list of methods that you can override, please see
__init__.py in the lib/ansible/plugins/callback directory.
The following example shows how Ansible’s timer plugin is implemented:
# Make coding more python3-ish from __future__ import (absolute_import, division, print_function) __metaclass__ = type from datetime import datetime from ansible.plugins.callback import CallbackBase class CallbackModule(CallbackBase): """ This callback module tells you how long your plays ran for. """ CALLBACK_VERSION = 2.0 CALLBACK_TYPE = 'aggregate' CALLBACK_NAME = 'timer' CALLBACK_NEEDS_WHITELIST = True def __init__(self): super(CallbackModule, self).__init__() self.start_time = datetime.now() def days_hours_minutes_seconds(self, runtime): minutes = (runtime.seconds // 60) % 60 r_seconds = runtime.seconds - (minutes * 60) return runtime.days, runtime.seconds // 3600, minutes, r_seconds def playbook_on_stats(self, stats): self.v2_playbook_on_stats(stats) def v2_playbook_on_stats(self, stats): end_time = datetime.now() runtime = end_time - self.start_time self._display.display("Playbook run took %s days, %s hours, %s minutes, %s seconds" % (self.days_hours_minutes_seconds(runtime)))
Note that the CALLBACK_VERSION and CALLBACK_NAME definitons are required.
By default, ansible ships with a ‘paramiko’ SSH, native ssh (just called ‘ssh’), ‘local’ connection type, and there are also some minor players like ‘chroot’ and ‘jail’. All of these can be used in playbooks and with /usr/bin/ansible to decide how you want to talk to remote machines. The basics of these connection types are covered in the Getting Started section. Should you want to extend Ansible to support other transports (SNMP? Message bus? Carrier Pigeon?) it’s as simple as copying the format of one of the existing modules and dropping it into the connection plugins directory. The value of ‘smart’ for a connection allows selection of paramiko or openssh based on system capabilities, and chooses ‘ssh’ if OpenSSH supports ControlPersist, in Ansible 1.2.1 and later. Previous versions did not support ‘smart’.
More documentation on writing connection plugins is pending, though you can jump into lib/ansible/plugins/connection and figure things out pretty easily.
Language constructs like “with_fileglob” and “with_items” are implemented via lookup plugins. Just like other plugin types, you can write your own.
More documentation on writing lookup plugins is pending, though you can jump into lib/ansible/plugins/lookup and figure things out pretty easily.
Playbook constructs like ‘host_vars’ and ‘group_vars’ work via ‘vars’ plugins. They inject additional variable data into ansible runs that did not come from an inventory, playbook, or command line. Note that variables can also be returned from inventory, so in most cases, you won’t need to write or understand vars_plugins.
More documentation on writing vars plugins is pending, though you can jump into lib/ansible/inventory/vars_plugins and figure things out pretty easily.
If you find yourself wanting to write a vars_plugin, it’s more likely you should write an inventory script instead.
If you want more Jinja2 filters available in a Jinja2 template (filters like to_yaml and to_json are provided by default), they can be extended by writing a filter plugin. Most of the time, when someone comes up with an idea for a new filter they would like to make available in a playbook, we’ll just include them in ‘core.py’ instead.
Jump into lib/ansible/plugins/filter for details.
Plugins are loaded from both Python’s site_packages (those that ship with ansible) and a configured plugins directory, which defaults to /usr/share/ansible/plugins, in a subfolder for each plugin type:
* action * lookup * callback * connection * filter * strategy * cache * test * shell
To change this path, edit the ansible configuration file.
In addition, plugins can be shipped in a subdirectory relative to a top-level playbook, in folders named the same as indicated above.
They can also be shipped as part of a role, in a subdirectory named as indicated above. The plugin will be availiable as soon as the role is called.