Working with Ansible - Cleanup tasks

My current project is heavily based on Ansible. We use Ansible to deploy into different environments and domains. The configuration has become quite complex. That is why we need to cleanup a server from time to time. Especially when one has to upgrade services on a server and requires to get rid of the old services first. In this post I would like to show you, how we define and run Ansible cleanup tasks in our project.

Imagine this simple directory structure:

roles/
  basic/
    tasks/
      main.yml
      clean.yml

With a very basic task:

main.yml

- name: install packages
  yum: name={{ item }} state=present
  with_items:
    - nano
    - git
    - vim

Now there is a scenario where we need to get rid of these packages before running the main task. For this reason with have the cleanup task:

clean.yml

- name: uninstall packages
  yum: name={{ item }} state=absent
  with_items:
    - nano
    - git
    - vim

It simply does the opposite of the main task.

Now how do we invoke the cleanup task? Well just include the task conditionally like this:

main.yml

- include: clean.yml
  when: clean

- name: install packages
...

Now whenever the main task is executed it will include the cleanup task if the variable clean is true. To run a reinstallation use the command: ansible-playbook _PLAYBOOK_.yml -e clean=true.

It is also possible to run the cleanup task only by using tags.

- include: clean.yml
  when: clean
  tags: clean

- name: install packages
...

Remember when you set a tag the tasks only using the tag are executed. Run this command to uninstall only: ansible-playbook _PLAYBOOK_.yml -e clean=true -t clean.

Of course you should avoid having cleanup task in the first place. Defining a rollback state is not very Ansible like.