An Amazon Machine Image is a packaged environment containing a software configuration and other parts required to set up an instance.
The machine images are like templates that are configured using an operating system, an application server, and any additional application required to deliver a service or a part of it.
The types of machine images are categorized based on operating system, launch permissions, region, system architecture (32- or 64-bit), and storage for the root device such as EC2 store or Amazon Elastic Block Store (Amazon EBS).
A user must specify a source AMI when setting up an instance. The user can set up multiple instances from one machine image when the instances are needed with a similar configuration. A user can also use different machine images to set up instances when instances with different configurations are needed.
What Do Amazon Machine Images Include?
Each Amazon Machine Image includes the following:
- A template for the instance’s root device volume
- Set up permissions that control which Amazon Web Services (AWS) accounts can use the machine images to set up an instance
- The block devices that specify the root device volume to attach to the E2C instance once it’s launched.
A read-only filesystem image - the main component of a machine image - is normally compressed, encrypted and uploaded into Amazon S3 for storage. The file used to store information about the machine image is known as a manifest file.
Information stored in this file includes name, architecture, decryption key and default kernel id. Note that an AMI does not include an image but rather a pointer to the default kernel id.
Types of Machine Images
These are machine images that are safe, secure and customized for public consumption.
These are images that can be purchased from a developer. EC2 users can purchase the images from the AWS Marketplace, an online store that sells software running on Amazon Web Services.
A private machine image can only be used by EC2 users who have been granted access to it by the developer.
Creating an Amazon Machine Image
A user can set up an instance using an existing Amazon Machine Image, customize it then save the updated configuration as a custom machine image.
To set up a Linux machine image backed by instance store, the user must create a machine image from their instance using the Amazon EC2 AMI tools.
How to Use Amazon Machine Images
After creating and registering an Amazon Machine Image, the developer can use it to set up new instances. The developer can then copy a machine image within the same region or other regions.
Additionally, the user can deregister a machine image if he/she no longer needs it. Have in mind that a deregistered machine image can’t be used to set up new instances.
A user can search for a machine image that meets the criteria of a certain instance or machine images provided by AWS or the community. When a user is connected to an instance, they can use it like any other server.