DevOps Classroom Series – 06/Oct/2021

How Ansible Works

• Configuration Management server in the case of the Ansible is called as Ansible Control Node which can be any linux, unix or mac instance.
• On all the NOdes Python should be installed
• Ansible uses python to do configuration management on the nodes, As an ansible user we would not need to know python to do Configuration Management
• Now lets consider that we would want to install apache on the web1, web2 and web3 nodes
  • Ansible should be configured
  • For doing deployment/installation we need to write a playbook which is a yaml.
  • Now we would ask ansible to execute playbook, Now Ansible will do the following
    • Generate a Python script that installs the apache
    • Copy the script to web1, web2 and web3
    • Execute the script on web1, web2 and web3
    • Wait for the script to complete and show the results
  • For copying and executing the python script created from playbook, Ansible needs to know the server details and credentials, we create a file called as inventory with server details where configuration management has to be executed.

Whats so great about Ansible

• Simple: Ansible was designed to have a simple setup process & minimum learning curve
• Easy to Read Syntax
• Easy to Audit
• Nothing to Install on Remote Hosts
• Easy to Share
• Powerful
  • Batteries
  • Paralled Execution
  • Master less

What Do i Need to Know to work with Ansible

• The following are the topics which we need to know about linux systems
  • Connect to a remote machine using SSH
  • Interact with command line shell
  • Install packages
  • Using the sudo command
  • Check and set file permissions
  • Start and stop Services
  • Set Environment variables

Ansible Lab Environment

• We would create two ec2 instances in AWS with ubuntu 20.04
• Note:
  • Creating AWS EC2 Refer Here
  • Creating Azure VMs Refer Here
• Now lets try to install ansible on one node which would be ansible control node
  • Log in to the ansible control node
  • Install on ubuntu Refer Here

  sudo apt update
  sudo apt install software-properties-common
  sudo add-apt-repository --yes --update ppa:ansible/ansible
  sudo apt install ansible -y
  

  
  • Now lets try to install python on the node 1. Python is already installed
  • In AWS instances, the password is disabled by default. So lets enable password based authentication on both ansible control node and node1
    • In the /etc/ssh/sshd_config lets set the value of PasswordAuthentication to yes
  • Then we would create an ansible user which simulates it admin on both the machines.
    • Log in to nodes and execute

  sudo adduser ansible
  

  
  • Now we need to give ansible user sudo privileges without prompting for password.

  sudo visudo
  

  
  • So now we have a sudo user ansible, so we need to configure in Ansible control node so that when ansible connects to node1, it connects as ansible user