Amazon Machine Images (AMIs) are pre-configured templates that contain the operating system, software, and configurations required to launch an EC2 instance. In this post, we will guide you through the process of creating a custom AMI from an existing EC2 instance and launching a new instance based on this custom AMI.

Steps to Create a Custom AMI

1. Launch and Configure Your Base EC2 Instance:

   • Go to the AWS Management Console.
   • Navigate to EC2 and launch an instance using an existing AMI (e.g., Amazon Linux, Ubuntu).
   • SSH into the instance and install any necessary software and configure it to your requirements:

     sudo yum install nginx -y    # Example: Installing Nginx on Amazon Linux
     sudo systemctl start nginx
     sudo systemctl enable nginx
     

2. Create the Custom AMI:

   • Once the instance is configured to your needs, navigate back to the EC2 Dashboard.
   • Select the instance you want to use for the custom AMI.
   • From the Actions menu, choose Image and templates > Create Image.
   • Fill in the details such as the name and description of the AMI, and optionally specify which volumes to include.
   • Click Create Image.

3. Wait for the AMI Creation:

   • AWS will take a snapshot of your instance and create the AMI. You can monitor the progress under Images > AMIs in the EC2 Dashboard.

Launch an EC2 Instance from the Custom AMI

1. Launch an Instance Using the Custom AMI:

   • Once your AMI is ready, go to AMIs in the EC2 dashboard.
   • Select your custom AMI and click Launch.
   • Choose the instance type, configure instance details, security group, and any other settings as needed.
   • Review and launch the instance.

2. Verify the Custom Setup:

   • Once the instance is running, SSH into the new instance to verify that all your custom configurations and software are in place:

     sudo systemctl status httpd    # Verify Nginx or any other custom software