What is an image builder?

An image builder is a tool used in system administration to create a copy—an exact image—of a virtual system or configuration (such as an operating system [OS], server, virtual machine [VM], container, etc.). Developers can use that copy as a base to build and deploy systems—or customized versions—on other machines, platforms, or other environments. 

Containers and container images, for example, are used in this way to move the code needed for an application from one system or platform to another. 

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With the original system configurations safe, developers can experiment and expand on the image/copy, keeping the original build components and adding features and functionality. This lets them learn and make improvements as they go without altering or damaging the original or its permissions. An image builder makes this possible without the developer needing to create each new image from scratch. 

The ability to spin up new instances of systems is an invaluable resource for devops, not only saving them the time of building the system copy themselves, but providing consistency with each image. This consistency and validation with image creation means no human errors that have to be fixed which, in turn, means more confidence in the system and efficiency in the process.

These images, often referred to as golden images or gold images, can be stored for access to each version as needed, similar to the way container registries are used.

A golden image (also known as a gold image, base image, clone image, or master image) is an image that is considered to be the final, perfect copy of the original system from which copies are made. The term originates from the media and film industries, which use it to signify the final cut or version of a film or album. It’s considered perfect and is therefore "golden."

From a security perspective, creating an image of the most ideal instance of your systems means having a backup copy that makes it easier to get up and running in less time should there be a failure or security breach. 

A golden image also prevents "drift" or "configuration drift"— a term meaning that a system has changed from its ideal baseline. This could indicate it has added or modified applications, security settings, or system configurations between the data center and recovery systems. Without a gold image baseline, it can be very difficult to identify when or how systems have been modified. This can be crucial to maintain compliance, regulatory, and industry standards. Using a baseline means that you can monitor systems for drift.

Golden images also let operations teams (such as systems administrators) create and manage a curated catalog of prebuilt images that can then be deployed by developers and database administrators for development and testing.

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Red Hat® Enterprise Linux® comes with its own image builder, allowing the creation of custom Red Hat Enterprise Linux system images in a selection of formats and configurations. Image builder is available as an on-premise tool or as a hosted service on the Red Hat Hybrid Cloud Console which helps you optimize your existing infrastructure and efficiently migrate and deploy future workloads. 

With Red Hat’s image builder, you can create customizable and repeatable OS images and server images with consistent provisioning and deployment across all environments—including system images prepared for deployment on cloud platforms. 

Image builder also automatically handles the details of how to deploy to a cloud, virtual machine or image, making it easier to use and faster to work with than creating images manually. Images built with image builder are compatible with the major cloud providers and virtualization technologies available so you can quickly spin up new Red Hat Enterprise Linux systems quickly on different platforms, according to your requirements.

With Red Hat’s image builder, you can build a custom image in a few simple steps: 

• Select your platform
• Choose between an on-premise build or the hosted version of image builder
• Create a template by defining filesystems, selecting packages, and configuring users
• Build the image
• Deploy.

Coming from a leading provider of open source enterprise Linux, Red Hat Enterprise Linux image builder creates pristine, never-before-booted images, avoiding update and cleanup operations, which can be prone to error. It's also used in all of Red Hat’s own build workflows and is fully tested and supported by Red Hat Quality Engineering. 

Building your systems (and their images) on a Red Hat foundation means you have access to these other benefits as well:

• Red Hat Lightspeed (formerly Red Hat Insights) gives visibility over your entire infrastructure. Using a set of baseline images can make it easier to identify vulnerable systems, create playbooks for automation, and track drift within systems.
• Red Hat’s Cloud Access program allows organizations to use their subscription with public cloud providers. As part of this program, Red Hat has created certified, prebuilt images for Amazon Web Services (AWS), Microsoft Azure, and Google Cloud for all of the major products from Red Hat, including Red Hat Enterprise Linux, middleware, and storage.
• Red Hat even has optimized, OCI-compliant container images as part of its Universal Base Image Catalog.

Image mode for Red Hat Enterprise Linux is a different method of deploying Red Hat Enterprise Linux where one builds, deploys, and manages the operating system (OS) using container technologies. Managing your OS with the same tools and workflows as application development can help create a consistent experience and common language across teams. 

Deploying Red Hat Enterprise Linux via package mode is a familiar experience across any footprint, where the OS is assembled and updated from RPM packages. Red Hat Enterprise Linux image builder is used when Red Hat Enterprise Linux is deployed in package mode. 

In image mode, Red Hat Enterprise Linux is delivered as an immutable bootc container image. Updates are built as new container images and pushed to the container registry, and updates are applied on top of the existing image. This makes it easy to uniformly roll updates out and back if needed. The new container file can be removed in one piece, returning to the original baseline.

Both modes run on bare metal, virtual machine, cloud, and edge deployments. 

Learn more about image mode for Red Hat Enterprise Linux→