What is AWS Amazon Machine Image (AMI)?

An Amazon Machine Image (AMI) is used to create virtual servers (Amazon Elastic Compute Cloud or EC2 instances) in the Amazon Web Services (AWS) environment. Different types of instances can be launched from a single AMI to support the hardware of the host computer used for the instance. With AMIs, it is faster and easier to set up an instance than with traditional software deployments as there is no manual set up, no configuration and no additional hardware.

AMIs can be created or acquired. Prebuilt AMIs can be found by searching AWS, the user community or the AWS marketplace. Custom AMIs can also be created by users or third-party providers (for example, from a vendor such as Aviatrix) to meet specific requirements. Custom AMIs can be kept private. They can also be shared or sold publicly.

The main component of an AMI is a read-only file system that is compressed, encrypted and stored in Amazon S3. AMIs include:

• A template for the instance’s root volume, which typically contains an operating system*, application server, and applications

• Permissions that restrict AMI instance launches to defined accounts

  • Public – launch permission granted to all AWS accounts

  • Explicit – launch permission only granted to specific accounts

  • Implicit – launch permission only granted for an AMI

• A block device mapping that directs which volumes are attached to a launched instance

Once an AMI has been created and registered, it can be reused to launch multiple instances with the same configuration. Tags can be used to categorize and manage AMIs. When an AMI is no longer needed, it can be deregistered. A deregistered AMI cannot be used to launch new instances, but existing instances will remain active.

*Amazon EC2 currently (as of March 2018) supports a variety of operating systems, including Amazon Linux, Ubuntu, Windows Server, Red Hat Enterprise Linux, SUSE Linux Enterprise Server, Fedora, Debian, CentOS, Gentoo Linux, Oracle Linux, and FreeBSD.

Ingress vs. Why AMIs matter

AMIs are a core building block for scalable cloud operations because they allow you to:

• Launch multiple EC2 instances with the same baseline configuration

• Deploy faster with repeatable, predictable builds

• Standardize OS and software versions across dev/test/prod

What’s inside an AMI (Amazon Machine Image)?

An AMI is primarily a read-only root file system stored in Amazon S3, and it includes:

• Root volume template (commonly the OS + application components)

• Launch permissions (who can use the AMI)

  • Public: usable by all AWS accounts

  • Explicit: usable only by specific accounts

  • Implicit: usable only by the AMI owner (private)

• Block device mapping (which EBS volumes attach when the instance launches)

What are the Types of AMIs?

AMIs can be created or acquired depending on your requirements:

Prebuilt AMIs

Prebuilt AMIs are available from AWS, the community, or the AWS Marketplace. They’re useful when you want a known baseline quickly.

Custom AMIs

Custom AMIs are created by users or third-party providers (including vendors such as Aviatrix) to meet specific requirements. Custom AMIs can be private, shared with specific accounts, or published publicly.

AMI lifecycle: create, reuse, tag, and retire

Once an AMI is created and registered, it can be reused to launch multiple instances with the same configuration. Tags can help categorize and manage AMIs across environments. When an AMI is no longer needed, it can be deregistered. A deregistered AMI can’t be used to launch new instances, but existing instances keep running.

AMI Lifecycle at a Glance

An AMI is a reusable blueprint for launching EC2 instances consistently. The flow begins with creating a snapshot of the instance’s root volume (or a template for instance-store backed images). After you register that snapshot as AMI #1, you can use it as a standardized source for deployment. From AMI #1, you can either launch an EC2 instance (repeatable provisioning), or copy the AMI to create AMI #2—commonly done to support a new region, share across accounts, or preserve a versioned “golden image.” When you deregister an AMI, it’s removed from the list of launchable images, which helps prevent accidental use of outdated baselines and supports lifecycle management.

Best practices for using AMIs

To keep AMIs secure and operationally consistent:

• Standardize naming and tagging (owner, app, environment, version, patch date)

• Use least-privilege launch permissions (avoid public AMIs unless there’s a clear reason)

• Patch and rebuild regularly (treat AMIs as “golden images” that are versioned and refreshed)

• Retire old AMIs to reduce security risk and prevent accidental use

• Validate regions and account sharing so teams launch the intended image every time

FAQs about Amazon Machine Image (AMI)

What is an AMI used for in AWS?

An AMI is used to launch EC2 instances quickly using a standardized template that includes OS and configuration details.

Can one AMI launch different instance types?

Yes. Different EC2 instance types can be launched from the same AMI to match the hardware requirements of the host computer used for the instance.

Are AMIs public or private?

AMIs can be private, shared with specific AWS accounts, or public depending on the configured launch permissions.

What happens if I deregister an AMI?

After deregistration, you can’t launch new instances from that AMI, but instances already running from it remain active.

Where is an AMI stored?

AMIs are stored in AWS and backed by a compressed, encrypted, read-only file system stored in Amazon S3.

What is the difference between EC2 and AMI?

EC2 is the compute service and the instance is the running virtual server. An AMI is the template used to launch that instance (OS, configuration, and startup baseline).

Are AMIs free in AWS?

Some AMIs are available at no additional charge (for example, certain AWS-provided images), but AMIs can still incur costs depending on what backs them—especially EBS snapshots and storage, and any licensed software included in Marketplace AMIs.

How much does an AMI cost?

The AMI itself is a template, but the cost typically comes from:

• Storage (EBS snapshots/volumes that back the AMI)

• Data transfer where applicable

• Software licensing (common with Marketplace AMIs) Pricing varies by region and what the AMI includes.

Why do we create AMI in AWS?

Teams create AMIs to standardize and speed up deployments. A well-managed AMI:

• reduces manual configuration

• improves consistency across environments

• supports repeatable scaling and recovery

Is AMI like a Docker image?

They are similar in concept because both are reusable “build artifacts,” but they operate at different layers. An AMI packages an entire machine environment for EC2 (OS and system configuration). A Docker image packages an application and its dependencies to run in a container runtime.

Can we delete AMI in AWS?

You can deregister an AMI so it can’t be used to launch new instances. You typically also delete the backing snapshots if you want to stop storage charges. Existing instances launched from that AMI are not automatically stopped.

What is the main purpose of AMI?

The main purpose of an AMI is to provide a repeatable, consistent template for launching EC2 instances, enabling faster provisioning and standardized configurations.

What is an AMI used for in AWS?

An AMI is used to launch new EC2 instances using a predefined operating system and configuration baseline.

Can one AMI launch different instance types?

Yes. The same AMI can be used to launch different EC2 instance types depending on the compute requirements.

What happens if I deregister an AMI?

After deregistration, you can’t launch new instances from that AMI, but existing instances continue to run.