Run a specific task in the end of play - ansible

Question

How I run a specific task when playbook all other tasks completed? The problem is that this needs to be done in every playbook. Just adding to every playbook is not a good idea, I need to make it common for everyone. There is one common role in every playbook, but it works in the beginning. Is it possible to add a task to it that would start at the very end? Or some other way to do this, so that it is always done at the end without editing each playbook.

Answer 1

You could do it with writing a Callback Plugin. This is python code, that executes pre-defined Functions when an (ansible-internal) event occurs.
Interesting for you would be the v2_playbook_on_stats method, which is on of the last steps executed.
For this, please checkout the basic Developer Guidelines page of Ansible:
https://docs.ansible.com/ansible/latest/dev_guide/index.html
But more importantly the Plugins Guide:
https://docs.ansible.com/ansible/latest/dev_guide/developing_plugins.html
The basic structure as outlined in the document is:
from ansible.plugins.callback import CallbackBase
class CallbackModule(CallbackBase):
pass
They even provide a proper example executing the v2_playbook_on_stats method:
# Make coding more python3-ish, this is required for contributions to Ansible
from __future__ import (absolute_import, division, print_function)
__metaclass__ = type
# not only visible to ansible-doc, it also 'declares' the options the plugin requires and how to configure them.
DOCUMENTATION = '''
callback: timer
callback_type: aggregate
requirements:
- whitelist in configuration
short_description: Adds time to play stats
version_added: "2.0"
description:
- This callback just adds total play duration to the play stats.
options:
format_string:
description: format of the string shown to user at play end
ini:
- section: callback_timer
key: format_string
env:
- name: ANSIBLE_CALLBACK_TIMER_FORMAT
default: "Playbook run took %s days, %s hours, %s minutes, %s seconds"
'''
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 = 'namespace.collection_name.timer'
# only needed if you ship it and don't want to enable by default
CALLBACK_NEEDS_WHITELIST = True
def __init__(self):
# make sure the expected objects are present, calling the base's __init__
super(CallbackModule, self).__init__()
# start the timer when the plugin is loaded, the first play should start a few milliseconds after.
self.start_time = datetime.now()
def _days_hours_minutes_seconds(self, runtime):
''' internal helper method for this callback '''
minutes = (runtime.seconds // 60) % 60
r_seconds = runtime.seconds - (minutes * 60)
return runtime.days, runtime.seconds // 3600, minutes, r_seconds
# this is only event we care about for display, when the play shows its summary stats; the rest are ignored by the base class
def v2_playbook_on_stats(self, stats):
end_time = datetime.now()
runtime = end_time - self.start_time
# Shows the usage of a config option declared in the DOCUMENTATION variable. Ansible will have set it when it loads the plugin.
# Also note the use of the display object to print to screen. This is available to all callbacks, and you should use this over printing yourself
self._display.display(self._plugin_options['format_string'] % (self._days_hours_minutes_seconds(runtime)))
I want to also highlight the importance of the DOCUMENTATION string. I first thought, that this is only for generating the Doc help page. But no. Checkout this Example:
options:
format_string:
description: format of the string shown to user at play end
ini:
- section: callback_timer
key: format_string
env:
- name: ANSIBLE_CALLBACK_TIMER_FORMAT
default: "Playbook run took %s days, %s hours, %s minutes, %s seconds"
In there you have ini, env, and default sections, these are actually used to inject options into your Callback plugin using self._plugin_options['format_string'] or using self.get_option("format_string") for a list of all callback methods that can be overriden, please refer to https://github.com/ansible/ansible/blob/devel/lib/ansible/plugins/callback/init.py
For you the methods starting with v2_ are interesting, because these are for Ansible 2+.
Checkout https://github.com/ansible/ansible/tree/devel/lib/ansible/plugins/callback for more examples.
But it seems, that they are cleaning up quite a lot at the moment.
Therefore, I would say, please checkout a Version Tag, like:
https://github.com/ansible/ansible/tree/v2.9.6/lib/ansible/plugins/callback
Hope this helps.