Ansible, Idempotency,

and Jenkins

Tyler Turk

DevOps Engineer - WP Engine

Brief Introduction on Me

DevOps Engineer at WP Engine

Passionate Ansible Advocate

Loves python and automation

Purpose of this talk?

Empower YOU to:

Use ansible and vagrants

Understand importance of idempotency

Test for idempotent playbooks

What is Ansible?The TL;DR Version

What does idempotency

mean?Why is this important? Why do we care?

What is jenkins?

Job scheduler

Job monitor

Job executor

Awesome

What is Jenkins not?

Want to follow along?

Vagrant:

https://github.com/tylerturk/jenkins_ansible_id

empotent_test_vagrant

Playbooks:

https://github.com/tylerturk/jenkins_ansible_id

empotent_test

Issues Faced

docker_image module is deprecated

SSH on Docker is considered evil

(https://jpetazzo.github.io/2014/06/23/docker-ssh-considered-evil/)

wait_for module just waits for TCP

connectivity

(http://docs.ansible.com/wait_for_module.html)

How are we doing this?

Custom python script

Ansible python API

Validating returned data

What’s under the covers?Vagrant provisioned with jenkins and docker

Vagrant builds a docker image that has

ansible

Jenkins provisions docker container with

ansible

Custom python script runs playbook a second

time

Returned results are then validated

Idempotent vs Not

Idempotent

Uses correct ansible

module

Job successfully builds

Profit!

Touches a file

Job fails miserably

Profit!

How can we make this

better?

Identify file and line number of non-

idempotent task

Use with docker and SSH

Improve callback to not write local file

Move traceback to more visible