Skip to content

Build Status

Lab 010 - Loops and Conditionals in Ansible

  • In this section, we will cover Loops and Conditionals in Ansible.
  • Loops assist in efficiently performing repetitive tasks.
  • Conditions allow tasks to be executed based on specific criteria.
  • See documentation about Loops and Conditionals in Ansible.

01. Ansible Loops

Basic loop

  • Ansible provides a loop keyword to execute tasks multiple times with different inputs:

---
- hosts: localhost
  tasks:
    - name: Install multiple packages
      apt:
        name: "{{ item }}"
        state: present
      loop:
        - git
        - curl
        - vim

Loop with dictionaries

  • Loops can be used with dictionaries to process structured data:

---
- hosts: localhost
  tasks:
    - name: Add multiple users
      user:
        name: "{{ item.name }}"
        shell: "{{ item.shell }}"
      loop:
        - { name: "alice", shell: "/bin/bash" }
        - { name: "bob", shell: "/bin/zsh" }

Nested loops

  • Nested loops allow iterating over multiple lists:
---
- hosts: localhost
  tasks:
    - name: Assign permissions
      file:
        path: "/home/{{ item.0 }}/{{ item.1 }}"
        state: touch
        owner: "{{ item.0 }}"
      loop:
        - ["alice", "bob"]
        - ["file1.txt", "file2.txt"]
      loop_control:
        loop_var: item

02. Ansible Conditionals

Using the when clause

  • Conditionals can be defined using the when clause:

---
- hosts: localhost
  tasks:
    - name: Install Apache only on Ubuntu
      apt:
        name: apache2
        state: present
      when: ansible_os_family == "Debian"

Complex conditionals

  • Multiple conditionals can be combined with and, or, and not clauses:
---
- hosts: localhost
  tasks:
    - name: Restart service only if running
      service:
        name: nginx
        state: restarted
      when: ansible_os_family == "RedHat" and ansible_distribution_major_version | int >= 7

03. Combining loops and conditionals

  • Loops and conditionals can be used together:
---
- hosts: localhost
  tasks:
    - name: Create users only if home directory does not exist
      user:
        name: "{{ item }}"
        state: present
      loop:
        - alice
        - bob
      when: not ansible_facts['getent_passwd'][item] is defined

Practice

04. Hands-on

  • Try writing a playbook that installs different packages based on the OS family.
  • Try to use as many parts as you can (external vars, vars, loops, conditions etc) while doing so.