Install Ansible and Run Your First Playbook

Prerequisites

1. Create two EC2 instances:
   • Main instance: Install Ansible.
   • Target instance: The system to configure.

Step 1: Install Ansible on the Main Instance

Commands:

sudo apt update
sudo apt install ansible

Verify Installation:

ansible --version

Step 2: Set Up Passwordless Authentication

On the Main Instance:

1. Generate an SSH Key Pair:

   ssh-keygen

The public key is usually located at ~/.ssh/id_rsa.pub.

1. Copy the Public Key: Open the file with a text editor (e.g., vim) and copy its contents.

On the Target Instance:

1. Log in:

   ssh <username>@<target_server_ip>

1. Paste the Public Key into ~/.ssh/authorized_keys:

   vim ~/.ssh/authorized_keys

Save changes with :wq.

1. Test SSH: From the main instance:

   ssh <target_server_ip>

Passwordless authentication should now work.

Step 3: Create an Inventory File

1. Create a file named inventory:

   [webservers]
   192.168.1.10
   192.168.1.11

   [databases]
   192.168.1.20

Step 4: Run Ad-Hoc Commands

1. Run a Command Across All Servers:

   ansible -i inventory all -m shell -a "command_to_execute"

1. Example:

   ansible -i inventory webservers -m shell -a "ls -la"

Step 5: Write and Run Playbooks

1. Create a Playbook (e.g., playbook.yml):

   ---
   - name: Update and upgrade systems
     hosts: all
     become: yes
     tasks:
       - name: Update package lists
         apt:
           update_cache: yes
       - name: Upgrade packages
         apt:
           upgrade: yes

1. Run the Playbook:

   ansible-playbook playbook.yml -i inventory

By following these steps, you’ll have a basic Ansible setup to manage your infrastructure effortlessly.