Master Ansible Automation: A Complete Guide to Playbooks, Modules, and Roles

Ansible Overview

Ansible is a popular open‑source automation tool that simplifies operations by enabling repeatable, error‑free management of large numbers of hosts.

Key Features

Python‑based, easy to extend for developers.

Rich built‑in modules covering most automation needs.

Agentless architecture using SSH.

Scales to thousands of machines with a single command.

Supported by major cloud providers and vendors.

Ansible Roles

How users interact with Ansible (CMDB, API, ad‑hoc commands, playbooks).

Core toolset includes Inventory, Modules, Plugins, and API.

Supported objects span Linux, non‑Linux, public/private clouds, and network devices.

Installation

Ansible can be installed via YUM; only Python and SSH are required. Example repository configuration and installation commands:

# cd /mnt/ansiblerepo/ansiblerepo/repodata/
# vim /etc/yum.repos.d/local.repo
[local]
name=centos
baseurl=file:///mnt/ansiblerepo/ansiblerepo
enabled=1
gpgcheck=0
# yum -y install ansible

Verify installation:

# ansible --version
ansible 2.3.1.0
config file = /etc/ansible/ansible.cfg
python version = 2.7.5

SSH Key Setup for Password‑less Login

# ssh-keygen -t rsa
# ssh-copy-id -i ~/.ssh/id_rsa.pub [email protected]
# ssh-copy-id -i ~/.ssh/id_rsa.pub [email protected]

Inventory Configuration

The inventory file (default /etc/ansible/hosts) defines host groups and can include ports, wildcards, and range expressions.

[web]
192.168.100.20
192.168.100.30
[test]
www.benet.com:222
mail
yj1.kgc.cn
yj[2:5].kgc.cn

Common Ansible Commands

ansible all -m ping

– check connectivity. ansible web --list – list hosts in a group. ansible web -m command -a "df -hT" – run ad‑hoc commands. ansible-playbook playbook.yml – execute a playbook.

Modules Overview

command : Executes a command without shell features.

shell : Executes a command with full shell support.

copy : Copies files to remote hosts.

hostname : Manages hostnames.

yum : Manages packages via YUM.

service : Controls services.

user : Manages user accounts.

Playbook Structure

Playbooks are YAML files that define hosts, remote_user, tasks, handlers, and roles. Example snippet:

---
- hosts: web1
  remote_user: root
  tasks:
    - name: add user
      user:
        name: user1
        state: present
      tags:
        - aaa
    - name: add group
      group:
        name: root
        system: yes
      tags:
        - bbb
- hosts: web2
  remote_user: root
  tasks:
    - name: copy file to web
      copy:
        src: /etc/passwd
        dest: /home
      tags:
        - ccc
...

Handlers and Roles

Handlers run only when notified by a task, ensuring actions like service restarts happen after configuration changes. Roles organize related tasks, handlers, files, templates, and variables under a directory structure (e.g., /etc/ansible/roles/mysql).

Example: Deploy MariaDB with a Role

The article outlines a full workflow: install MariaDB, copy configuration files, restart the service, create a database, and grant privileges, all orchestrated through Ansible roles and playbooks.