Ansible is a tool that used to manage various nodes from an ansible installed Controlling Machine using SSH Protocol. It makes every system administrative tasks more easy.

Ansible Playbook is a organised unit of scripts which is working in the Controller machine (Ansible installed system). Playbook are written in YAML format.

Install Ansible on Centos 7:-

Controller Machine IP:- 10.0.0.209

Node IP :- 10.0.0.206
10.0.0.207

* more ip can be used.

Step 1 :-
Install Ansible using yum in Controller Machine. Check the version of the installed Ansible.

# yum install ansible

# ansible --version

Step 2 :-
Setup Controlling Machine to connect node using ssh protocol.
Create ssh key to access node systems and copy the key to the node.

# ssh-keygen

# ssh-copy-id root@10.0.0.206
# ssh-copy-id root@10.0.0.207

Step 3:-
Add ips of node systems into the Inventory of Ansible by editing /etc/ansible/hosts .

# vim /etc/ansible/hosts
[ansi-test]
10.0.0.206
10.0.0.207

Note: Here both ip can call using name ansi-test

Step 4:-
Test Ansible in the Controller Machine by using below commands.

1. First of all test the Controlling Machine have ping with node system using ansible commands.

# ansible -m ping all

10.0.0.206 | SUCCESS => {
    "changed": false, 
    "ping": "pong"
}
10.0.0.207 | SUCCESS => {
    "changed": false, 
    "ping": "pong"
}

Now Lets start to work with Ansible Playbook.

Create Ansible Playbook for CRON :-

Our requirement is to take backup of /test folder to /backup folder at every day 12:00 in all the nodes that are configured to the controller machine with Ansible.

First make /test folder and /backup folder.

# mkdir /backup
# mkdir /test

Now we need to write a backup shell script in the folder /backup_script with the name backup.sh . This script are need to transfer all nodes.

# vim /backup_script/backup.sh

#!/bin/bash
tar vcf /backup/backup_test.`date +\%Y-\%m-\%d_\%H:\%M:\%S`.tar /test

Setup Ansible playbook and create yml script for cronjob :-

Make a directory Playbooks in side /etc/ansible.

# mkdir /etc/ansible/playbooks

Create cron.yml using vim tool.

# vim /etc/ansible/playbooks/cron.yml

  tasks:
  - name: Install a yum package in Ansible
    yum:
      name: crontabs
      state: present
  - name: copy the script into node systems
    copy: src=/backup_script/backup.sh dest=/root/
  - name: create a cron in node systems
    cron:
        name: "Backup Cron"
        user: "root"
        minute: 00
        hour: 12
        job: "/usr/bin/sh /root/backup.sh 2>&1"

Now we have created Ansible Playbook with name cron.yml. Execute the following command to run the script using Ansible.

# ansible-playbook /etc/ansible/playbooks/cron.yml