Install and use Ansible (Automation Tool) in CentOS 7

Ansible is a free & open source Configuration and automation tool for UNIX like operating system. It is written in python and similar to Chef or Puppet but there is one difference and advantage of Ansible is that we don’t need to install any agent on the nodes. It uses SSH for making communication to its nodes.

In this article we will demonstrate how to install and configure Ansible in CentOS 7 and will try to manage its two nodes.

Ansible Server – ansible.linuxtechi.com ( 192.168.1.15 )
  Nodes                – 192.168.1.9 , 192.168.1.10

Step :1 Set EPEL repository

Ansible package is not available in the default yum repositories, so we will enable epel repository for CentOS 7 using below commands

[[email protected] ~]# yum install epel-release -y

Step:2 Install Anisble using yum command

[[email protected] ~]# yum install ansible

Once the installation is completed, check the ansible version :

[[email protected] ~]# ansible --version

Step:3 Setup keys based SSH authentication with Nodes.

Generate keys on the Ansible server and copy public key to the nodes.

[email protected] ~]# ssh-keygen

Use ssh-copy-id command to copy public key of Ansible server to its nodes.

Step:4 Define the nodes or inventory of servers for Ansible.

File ‘/etc/ansible/hosts‘ maintains the inventory of servers for Ansible.

[[email protected] ~]# vi /etc/ansible/hosts
[test-servers]
192.168.1.9
192.168.1.10

Save and exit the file.

Sample output of hosts file.

Step:5 Now try to run the Commands from Ansible Server.

Check the connectivity of ‘test-servers’ or ansible nodes using ping

[[email protected] ~]# ansible -m ping 'test-servers'

Executing Shell commands :

Example :1 Check the uptime of Ansible nodes

[[email protected] ~]# ansible -m command -a "uptime" 'test-servers'

Example:2 Check Kernel Version of nodes

[[email protected] ~]# ansible -m command -a "uname -r" 'test-servers'

Example:3 Adding a user to the nodes

[[email protected] ~]# ansible -m command -a "useradd mark" 'test-servers'
[[email protected] ~]# ansible -m command -a "grep mark /etc/passwd" 'test-servers'

Example:4 Redirecting the output of command to a file

[[email protected] ~]# ansible -m command -a "df -Th" 'test-servers' > /tmp/command-output.txt

Read Also: How to Download and Use Ansible Galaxy Roles in Ansible Playbook