Master Ansible Basics: Essential Modules and Commands for Automation

Introduction

This article, originally presented by Linux operations expert Wei Wei, introduces the fundamentals of Ansible for beginners and intermediate automation engineers.

Ansible Architecture

Ansible consists of several core components:

Ansible core : the Ansible software itself.

Host inventory : a list of managed hosts defined in /etc/ansible/hosts.

Core modules : built‑in modules that perform most tasks.

Custom modules : user‑written modules for specific functions.

Playbook : a file that defines a series of tasks.

Connection plugin : handles the initial connection to the first managed host.

Host Inventory and Variables

Hosts are defined in /etc/ansible/hosts. Example entry:

[webservers]
www1.magedu.com http_port=80 maxRequestsPerChild=100
www2.magedu.com http_port=8080 maxRequestsPerChild=200

Host‑specific variables can be added in the inventory and are accessible within playbooks. Group variables are defined for all hosts in a group, e.g.:

[webservers:vars]
ntp_server=ntp.magedu.com
nfs_server=nfs.magedu.com

Basic Ansible Command Syntax

The general command format is:

ansible <host-pattern> [-f forks] [-m module_name] [-a args]

Common options: -f forks: number of parallel processes. -m module_name: module to use. -a args: arguments for the module.

Key Modules and Examples

Group Module

Creates or manages groups on remote hosts.

# ansible datanodes -m group -a 'name=developer'

Result example:

{
  "changed": true,
  "gid": 501,
  "name": "developer",
  "state": "present",
  "system": false
}

To delete the group:

# ansible datanodes -m group -a 'name=developer state=absent'

User Module

Manages user accounts.

# ansible all -m user -a 'name=dev uid=666 group=developer'

To remove the user:

# ansible all -m user -a 'name=dev uid=666 group=developer state=absent'

Copy Module

Transfers files to remote hosts.

# ansible datanodes -m copy -a 'src=/etc/issue dest=/tmp/issue.ansible mode=600 owner=zabbix'

Using the content parameter to create a file with inline text:

# ansible datanodes -m copy -a 'content="hello world!
 how are you? 
" dest="/tmp/content.ansible"'

Cron Module

Manages scheduled tasks.

# ansible data1 -m cron -a 'name="pingtest" minute="*/1" job="ping www.baidu.com"'

To delete a job, set state=absent.

Shell Module

Executes commands on remote hosts, supporting shell features like pipelines.

# ansible target -m shell -a 'ps aux | grep httpd'

Ping Module

Checks network connectivity; a successful host returns pong.

# ansible all -m ping

Getting Module Help

Use ansible-doc to list modules or view detailed documentation.

ansible-doc -l          # list all modules
ansible-doc -s group   # show example usage for the group module

The left column shows module names, the right column provides brief descriptions.