Amazon Machine Image (AMI) – Everything You Need to Know

Amazon Machine Image (AMI) is a crucial component in AWS when launching EC2 instances. It acts as a blueprint, containing an operating system, application server, configurations, and software packages, enabling quick deployment of virtual machines on the cloud.

In this blog, we will cover:

• What is an AMI?

• Why do we use AMIs?

• How to create and manage AMIs

• Advantages and disadvantages

• Cost considerations

• Best practices for using AMIs

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What is an AMI?

An Amazon Machine Image (AMI) is a pre-configured template that provides the necessary information to launch EC2 instances in AWS. It includes:

• Base OS (Linux, Windows, etc.)

• Pre-installed software (Apache, MySQL, Java, etc.)

• Configuration settings

• Application data (optional)

When you launch an EC2 instance, AWS copies the AMI to an Elastic Block Store (EBS) and boots up a virtual server based on it.

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Why Use AMIs?

AMIs simplify infrastructure deployment and offer scalability, consistency, and efficiency in cloud computing.

1. Fast and Consistent Deployments

• Instead of manually configuring new servers, AMIs let you launch pre-configured instances instantly.

• Ensures that every instance has the same software and configurations.

2. Scalability

• Easily scale applications by launching multiple instances from the same AMI.

• Useful for auto-scaling groups in high-traffic applications.

3. Disaster Recovery & Backups

• Creating AMIs from running EC2 instances allows you to quickly restore instances in case of failure.

• Ideal for backup strategies and maintaining system states.

4. Cost Optimization

• Using custom AMIs with only necessary software reduces unnecessary resources and costs.

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How to Create an AMI in AWS?

Step 1: Select the EC2 Instance

• Go to EC2 Dashboard → Instances

• Choose the instance you want to create an AMI from

Step 2: Create an AMI

• Click on Actions → Image and templates → Create Image

• Provide an Image Name and Description

• Select the Volumes to be included

• Click Create Image

Step 3: Verify AMI Creation

• Go to EC2 Dashboard → AMIs

• You will see the new AMI in the "Pending" state (it takes a few minutes to become "Available").

Step 4: Launch an Instance from AMI

• Go to EC2 Dashboard → AMIs

• Select the AMI → Click Launch Instance from AMI

• Configure instance settings and launch it

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How to Delete an AMI to Stop Charges?

AWS charges for AMI snapshots stored in EBS. Simply terminating an instance does not delete the AMI or its associated snapshots.

Step 1: Deregister the AMI

• Go to EC2 Dashboard → AMIs

• Select the AMI → Click Actions → Deregister AMI

Step 2: Delete Associated Snapshots

• Go to EC2 Dashboard → Snapshots

• Find the snapshot linked to the AMI

• Click Delete

Deleting the snapshots ensures no further storage costs.

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Advantages of AMIs

✅Faster Deployments: Launch EC2 instances quickly without manual configuration.
✅ Scalability: Helps in Auto Scaling Groups to handle traffic fluctuations.
✅ Consistency: Ensures identical setups across environments.
✅ Backup & Recovery: Take snapshots and AMIs to restore instances when needed.
✅ Custom Configurations: Pre-install software, security settings, and dependencies.

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Disadvantages of AMIs

❌ Storage Costs: Even when not in use, AMIs and their snapshots incur storage charges.
❌ Outdated Configurations: If not updated regularly, AMIs can contain outdated software.
❌ Limited Flexibility: Any post-launch changes require creating a new AMI.
❌ Region-Specific: AMIs are region-bound, and you need to copy them to other regions manually.

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Cost Considerations for AMIs

AWS charges for:

• Snapshots stored in Amazon EBS (after AMI creation).

• Running instances created from AMIs (billed as per EC2 pricing).

• Data transfer if copying AMIs across regions.

To reduce costs:

• Deregister unused AMIs and delete snapshots.

• Use minimal storage for AMIs by keeping only required configurations.

• Leverage AWS Free Tier to test AMIs without charges.

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Disabling AMI

The "Disable AMI" option restricts its usage.

• Instances cannot be launched from the disabled AMI.

• The AMI remains stored, incurring EBS snapshot charges.

• It does not delete the AMI or its associated snapshots.

⚠️ Disabling AMI does NOT stop charges! If you want to avoid charges, you must:

1. Deregister the AMI

2. Delete the associated snapshots

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Best Practices for Using AMIs

✔ Use Custom AMIs – Create AMIs tailored to your workloads to speed up deployments.
✔ Update AMIs Regularly – Ensure software and security patches are up to date.
✔ Tag AMIs – Use AWS tags to organize AMIs by purpose, environment, or team.
✔ Limit the Number of AMIs – Regularly delete unused AMIs to save costs.
✔ Copy AMIs Across Regions – For high availability, copy AMIs to different regions.

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Conclusion

Amazon Machine Images (AMIs) are powerful tools for deploying and scaling applications in AWS. They help maintain consistency, speed up provisioning, and ensure disaster recovery. However, managing AMIs efficiently is key to avoiding unnecessary costs.

By following these best practices, you can optimize your cloud infrastructure and reduce costs while leveraging AMIs for efficient deployments.