DevOps Classroom notes – 15/Nov/2019

Ansible Variable Files

• Rather than having inventory and variables defined in same file, lets use Variable files.
• Variable files are of two categories
  • group_vars
  • host_vars
• Directory Structure should
  • Playbook
  • Inventory
  • group_vars
    • group_name
  • host_vars
    • host_name
• Lets design the directory structure for the following inventory

[ubuntu]
172.31.26.196

[redhat]
172.31.25.93

[webservers]
172.31.26.196
172.31.25.93

• The directory structure would be
  • lamp.yml
  • hosts
  • group_vars
    • webservers
    • redhat
    • ubuntu
  • host_vars
    • 172.31.26.196
    • 172.31.25.93
• Create files in the group_vars and host_vars
• Refer this sample over here
• Lets execute this command

ansible-playbook -i hosts -e package_name=stress lamp.yml

Ansible Variable Precedence

• Refer Here
• In majority of Cases variables are defined
  • In Playbook
  • In Inventory
  • In Inventory group_vars and host_vars
  • set fact
  • Roles
  • extra vars

Ansible Special Variables

• Refer Here

Adding a custom fail message for unsupported OS

• After adding a fail message for unsupported os, the playbook looks like

---
- hosts: webservers
  become: yes
  tasks:
    - name: fail if it is unsupported os
      fail:
        msg: This playbook is supported only on redhat and debain variants
      when: ansible_facts['os_family'] != "RedHat" and ansible_facts['os_family'] != "Debian"
    - name: install apache
      package: 
        name: "{{ package_name }}"
        state: present
      notify:
        - restart and enable apache
    - name: printing php modules
      debug:
        var: php_modules
    - name: install php modules
      package:
        name: "{{ item }}"
        state: present
      loop: "{{ php_modules }}"
    - name: Download info php page
      get_url:
        url: https://qt-s3-new-testing.s3-us-west-2.amazonaws.com/info.php
        dest: /var/www/html/info.php
      notify:
        - restart and enable apache
  handlers:
    - name: restart and enable apache
      service:
        name: "{{ package_name }}"
        enabled: yes
        state: restarted

• In our next series we will cover about
  • files
  • templates
  • Roles
  • set facts (pre and post tasks)
  • Ansible tower