Ansible: Up and Running, 3rd Edition

Chapter 18. Callback Plug-ins

Ansible supports a feature called callback plug-ins that can perform custom actions in response to Ansible events, such as a play starting or a task completing on a host. You can use a callback plug-in to do things such as send a Slack message or write an entry to a remote logging server. In fact, the output you see in your terminal when you execute an Ansible playbook is implemented as a callback plug-in.

Ansible supports three kinds of callback plug-ins:

• Stdout plug-ins

• Notification plug-ins

• Aggregate plug-ins

Stdout plug-ins control the format of the output displayed to the terminal. Ansible’s implementation makes no distinction between notification and aggregate plug-ins, which can perform a variety of actions.

Stdout Plug-ins

Only a single stdout plug-in can be active at a time. You specify a stdout callback by setting the stdout_callback parameter in the defaults section of ansible.cfg. For example, here is how to select the yaml plug-in, which makes the logging more readable:

[defaults]
stdout_callback = yaml

You can use ansible-doc -t callback -l to see the list of plug-ins available in the version you installed. Some stdout_callback plug-ins that Bas finds interesting are listed in Table 18-1.

Table 18-1. Stdout plug-ins

Name	Description	Python requirement
ara	ARA Records Ansible	ara[server]
debug	Formatted stdout/stderr display
default	Default Ansible screen output
dense	Overwrite output instead of scrolling