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Ansible

Introduction​

This cheat sheet provides a quick reference for some common Ansible commands and concepts. Ansible is an open-source automation tool for configuration management, application deployment, and task automation.

Installation​

To use Ansible, you need to install it on your control node. Installation methods may vary depending on your operating system. Refer to the official Ansible documentation for installation instructions.

Configuration​

Before using Ansible, you should configure your inventory and create Ansible playbooks.

Inventory​

The inventory file defines the hosts and groups that Ansible will manage. It is usually named inventory or hosts and can be stored in /etc/ansible/ or your project directory.

Example inventory file (inventory.yml):

web_servers:
  hosts:
    web1.example.com:
    web2.example.com:

db_servers:
  hosts:
    db1.example.com:
    db2.example.com:

# Group vars can be defined for each group
web_servers:
  vars:
    ansible_ssh_user: ubuntu
    ansible_ssh_private_key_file: /path/to/your/private_key.pem

Ansible Playbooks​

Playbooks are written in YAML and define a series of tasks to be executed on hosts. Create a playbook file (e.g., my_playbook.yml) to get started.

Example playbook (my_playbook.yml):

---
- name: My Ansible Playbook
  hosts: web_servers
  tasks:
    - name: Ensure Nginx is installed
      apt:
        name: nginx
        state: present

    - name: Start Nginx service
      service:
        name: nginx
        state: started

Common Ansible Commands​

Running Playbooks​

  • Run a playbook on all hosts:

    ansible-playbook my_playbook.yml

  • Run a playbook on specific hosts or groups:

    ansible-playbook -i inventory.yml -l web_servers my_playbook.yml

Ad-Hoc Commands​

  • Run an ad-hoc command on hosts:
    ansible -i inventory.yml -m <module> -a "<module_arguments>" web_servers

Variables​

  • Define variables in playbooks:

    vars:
      my_variable: "some_value"

  • Access variables in playbooks or templates:

    {{ my_variable }}

Conditionals​

  • Use conditionals in tasks:

    when: my_variable == "desired_value"

Loops​

  • Use loops in tasks:

    with_items:
      - item1
      - item2

Conclusion​

This cheat sheet covers some basic Ansible concepts and commands. Ansible provides extensive documentation; refer to the Ansible documentation for more in-depth information and advanced usage.