Automation with Linux

Ansible is an open-source tool for automating Linux stuff

Ansible

It helps administrators configure their servers with one click. For example, the admin wants to change DNS settings in every single Linux server.

Example: /etc/resolve.conf

nameserver 10.0.80.11
nameserver 10.0.80.12

By using Ansible, the admin only need to change the setting on the master server.

Get Started

{: .box-note} Demo - using three CentOS 7 VM

Step 1: Install Ansible

Enable EPEL repository: yum install epel-release -y
Install Ansible: yum install ansible -y

Step 2: Add hosts

Add hosts to your master server

/etc/ansible/hosts

[myLinux]

192.168.1.11 # server 2
192.168.1.12 # server 3

[myLinux:vars]

ansible_user=root
ansible_password=password

{: .box-error} Disclaimer - Don’t use root account for production

Skip the SSH key checking

/etc/ansible/ansible.cfg

# SSH
host_key_checking = False

{: .box-error} Disclaimer - SSH key is needed for production

Step 3: Check the connections

Use ping to check the connection between servers.

# Ping
ansible linux -m ping

# Reboot
ansible linux -a "reboot"

Done!

Playbook - Advanced Feature

There are more and more features for you. The YAML file is used to help organize our plays (tasks).

/etc/anisble/myTask.yml

# Task: Check for nano
---
- name: myTask
  hosts: myLinux
  tasks:
    - name: ensure nano is there
      yum:
        name: nano
        state: latest

We can run the playbook task with ansible-playbook myTask.yml. The playbook is trying to install the latest nano. They will show you if there are any changes with the changed=1 in the result.

Credit: Networkchuck

Tags: Automation