Event driven automation with Ansible

What is this all about?

Just a few weeks ago we have had a new significant development in the Ansible space, it is the introduction of Event-Driven Ansible. It includes new tools which allows you to automatically trigger automation using events. This is what many of our customers have been doing with Ansible Automation Platform, Event-Driven Ansible both makes it easier to do and available to everyone, also those doing Ansible outside of Ansible Automation Platform and AWX.

Event-Driven Ansible is in developer preview, which means that we are collecting feedback. Get engaged and influence the development of this significant piece of technology. The upstream open source project lives here: https://github.com/ansible/event-driven-ansible

As Event-Driven Ansible matures, a qualified guess is that we can look forward for more event-driven features in Ansible Automation Platform as well ;)

I am myself very excited regarding this. Read on to learn more.

Review of what Event-Driven Ansible is

Let's dive into it all. First off, there's a compliment to the Ansible playbook, and it is called a rulebook. Rulebooks gets read by ansible-rulebook, just as playbooks are read by ansible-playbook.

Rulebooks are just as playbooks written in YAML but has some different structure. Let's have a look at one.

There are three parts of a rulebook:

• Source?- The sources of our events come from source plugins. These plugins define where we are listening for events. There is support for a lot of different sources and more are planned to be added. View a list over current source plugins here: https://github.com/ansible/event-driven-ansible/tree/main/plugins/event_source. In our rulebook above, we use the url_check event source, which will produce two types of events, up and down.
• Condition?- The conditional statements in the rulebook allow us to match criteria on which we want to have some kind of response to. Depending on source plugin, we have different conditions we can deal with. Many source plugins allows for an arbitrary number of different event types and therefor conditions we can define. The as the url_check plugin only provides two types of events, up and down, we can only have two conditions in our rulebook.
• Action?- Lastly, the action is our response once the condition as been met from the event source. The action is the execution of a playbook. This can be done to trigger any automation of course, such as remediation, log a ticket for observation or generate other events which we would want to respond to. In our rulebook, we refer to two playbooks, site_up.yml and site_down.yml which we trigger depending on condition.

Here's the site_up.yml playbook:

Here's the site_down.yml playbook:

And here is what running the rulebook looks like:

ansible-rulebook --rules website-automation.yml -i inventory.yml --verbose

Try it out for yourself

You can access our free online lab to try out both the url_check example described above and another lab which uses the kafka source plugin here: https://www.ansible.com/products/ansible-training#event-driven-automation

If you want to try it out on your own systems, have a look at this repository, where I have put example rulebooks and playbooks: https://github.com/mglantz/event-driven-ansible-demo

To install ansible-rulebook, do this:

$ pip3 install ansible-rulebook
$ export JAVA_HOME=/usr/lib/jvm/java-17-openjdk        

Read more

This blog from Emily Bock is an excellent read: https://www.ansible.com/blog/introducing-event-driven-ansible