Minimize conditionals with Ansible

stacksofplates

So in Ansible you can use conditionals when a fact is different between systems (eg distribution, release, ip address, etc). You can also use variables with dictionaries and facts to accomplish this. Here is an example using a dictionary with package names for Apache:

---
# vars file for test
dist_hash:
    "RedHat":
        webserver: 'httpd'
    "Fedora":
        webserver: 'httpd'
    "Ubuntu":
        webserver: 'apache2'

webserver: "{{ dist_hash[ansible_distribution]['webserver'] }}"

The variable that will be called in the task is at the bottom. That variable references the hash (dictionary) above it. So it looks in dist_hash for the distribution (in my case Fedora) and replaces ansible_distribution with the actual name. Then it looks at the webserver value of the hash under that distribution name.

I set up a simple task that copies a template called test.j2 with these contents:

We will install {{ webserver }} on this system.

The main task file is this:

---
# tasks file for test
- name: test
  template:
    src: test.j2
    dest: /tmp/test.conf
    owner: root
    group: root
    mode: 0644

So it copies test.j2 and fills in the variable and stores it as /tmp/test.conf. Here's the output of that file:

[jhooks@starscream tmp]$ cat test.conf 
We will install httpd on this system.

This is one way to keep conditionals to a minimum in your roles.