What is Ansible?

• Ansible is a software tool that provides simple but powerful automation for cross-platform computer support. It is primarily intended for IT professionals, who use it for application deployment, updates on workstations and servers, cloud provisioning, configuration management, intra-service orchestration, and nearly anything a systems administrator does on a weekly or daily basis.

• Ansible doesn't depend on agent software and has no additional security infrastructure, so it's easy to deploy.

How Ansible Works?

• Ansible works by connecting to nodes (clients, servers, or whatever you're configuring) on a network, and then sending a small program called an Ansible module to that node. Ansible executes these modules over SSH and removes them when finished.

• SSH keys are the most common way to provide access, but other forms of authentication are also supported.

Ansible Architecture: Nodes and Modules

• Ansible's Architecture is based on the concept of a control node and a managed node. The platform is executed from the control node where a user runs the ansible-playbook command. There must be at least one control node; a backup control node can also exist. The devices being automated and managed by the control node are known as managed nodes.

• Ansible automates Linux and Windows by connecting to managed nodes and pushing out small programs called Ansible modules. Ansible executes these modules, which are the resource models of the desired system state, over Secure Socket Shell (SSH) by default and removes them when finished.

• Ansible modules are written in Python and can be written in any language. Ansible modules are reusable, standalone scripts that can be used by the Ansible API, Ansible Playbooks, or Ansible Galaxy.

Create 3 Instances on AWS EC2 with the following names:

• Ansible_Master_Server

• Node_1

• Node_2

Task-01: Installation of Ansible on AWS EC2 (Master Node)

• Step-01: Open Ansible_Master_Server and run the following commands or create a script for it:

#!/bin/bash
sudo apt-add-repository ppa:ansible/ansible
sudo apt update
sudo apt install ansible

• Step-02: Give permission to the script and run it:

sudo chmod 777 install.sh
sudo ./install.sh

• Step-03: Check the Ansible version:

ansible --version

Task-02: Ansible Host files

What is a Host file?

• In the context of Ansible, a host file (also known as an inventory file) is a configuration file used to define and organize the list of target hosts that Ansible should manage.

Where is the Host file located?

• Ansible uses this file to map target hosts to managed nodes. The host's file is usually located in /etc/ansible/hosts.

• So, open the host's file and add the IP addresses of the Nodes:

sudo vim /etc/ansible/hosts

• Step-04: Let's add the Node IP addresses in the host's file:

[servers]
Node_1 ansible_host= <Public IP-Adddress of Node-1>
Node_2 ansible_host= <Public IP-Adddress of Node-2>

[all:vars]
ansible_python_interpreter=/usr/bin/python3
ansible_ssh_private_key_file=/home/ubuntu/.ssh/id_rsa

• Step-05: Now, let's check the Ansible inventory:

ansible-inventory --list -y -i /etc/ansible/hosts

Let's Create an SSH Key on Ansible_Master_Server and copy its Public Key in Node_1 and Node_2.

• Step-06: Create an SSH Key on Ansible_Master_Server

cd /home/ubuntu/.ssh
ssh-keygen

cat id_rsa.pub

• Step-07: Copy the Public Key of Ansible_Master_Server and paste it in Node_1.

# Open Node_1
cd /home/ubuntu/.ssh
sudo vim authorized_keys

• Paste the Public Key of Ansible_Master_Server in Node_1.

• Step-08: Copy the Public Key of Ansible_Master_Server and paste it in Node_2.

# Open Node_2
cd /home/ubuntu/.ssh
sudo vim authorized_keys

• Try a ping command using Ansible to the Nodes.

ansible all -m ping

• Thus we have Pinged Node_1 and Node_2 from Ansible_Master_Server.

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Happy Learning :)