Introducing Image Customizer for Azure Linux

We are excited to release Image Customizer, an open-source tool, built and maintained by the Azure Linux team. Image Customizer lets you customize well-tested existing Azure Linux images for any scenario in just minutes. Already trusted by first party teams like LinkedIn, Azure Frontdoor, and Azure Nexus in production, this tool is designed to make image customization simple, reliable, and fast. With full dm-verity support for enhanced security, it also supports customization of Azure Linux with OS Guard images. 

Unlike VM-based image customization, Image Customizer directly modifies the image without booting a VM using a chroot-based approach, making customization faster, more reliable, and easier to integrate into existing workflows.

✨ Get Image Customizer here

✨ Explore our documentation here.

Why Choose Image Customizer?

Direct, Reliable Customization

• • Build on top of bootable, tested, and supported base images.
  • Lower overhead and fewer side effects by avoiding VM boot.
  • No need to rely on the Azure Linux Toolkit. Previously, building from scratch meant your image may fail to boot sometimes. Image Customizer reduces that risk.

Clean and Lightweight

• • Minimal dependencies for a streamlined setup (for example, no SSH required).
  • You only need to invoke one command to run Image Customizer. It is available as a container with all its dependencies bundled for easy integration into CI/CD pipelines.

Versatile and Powerful

• • Supported input formats: vhd, vhdx, qcow2, PXE bootable artifacts, raw and iso created by Image Customizer.
  • Supported output formats: vhd, vhd-fixed, vhdx, qcow2, raw, iso, and cosi.
  • Perform a wide range of operations: add/remove/update packages, add files and directories, create/update users, enable/disable services, customize partitions, image history, dm-verity and more. Full list of supported operations can be found here.

Cross-Platform Compatibility

• • Tested and verified to work on Ubuntu 22.04, Azure Linux 3.0 and WSL2 (Windows Subsystem for Linux). While officially tested on these platforms, Image Customizer will likely work on other Linux distributions as well.

Consistent and Predictable Builds

• • Use --package-snapshot-time or snapshotTime to filter packages by publication timestamp, ensuring only packages available at that point in time are considered. This prevents unexpected changes from newer package versions when reusing configuration files across time.

Getting Started with Image Customizer

To use Image Customizer, you’ll need a configuration file that describes the changes you want to make, using the Declarative API provided by Image Customizer. Next, select a base Azure Linux image as your foundation. With these two pieces in hand, you’re ready to run Image Customizer. The easiest way is to use the Image Customizer container, which comes pre-packaged with all necessary dependencies and is recommended for most users. Alternatively, you can use the standalone executable binary if that better fits your workflow. In just a few minutes, Image Customizer will generate a modified Azure Linux image tailored to your needs. This process is designed to be repeatable and user-friendly, making it easy to add packages, files, users, make partition changes, and much more.

To help you get started, we have a Quick Start  guide that walks you through your first customization step by step. For those who want to explore further, comprehensive API documentation is available, covering both Command-line usage and Configuration options.

Upcoming Community Call

Join our upcoming community call to learn more about using Image Customizer and see a live demo. We’ll cover best practices, advanced scenarios, and answer any questions you may have.

Date & Time: September 25^th, 2025 at 8:00AM PST

Teams Link: Azure Linux - External Community Call | Meeting-Join | Microsoft Teams

Community Call Schedule: https://learn.microsoft.com/en-us/azure/azure-linux/support-help#stay-connected-with-azure-linux

Help and Feedback

If you’d like to report bugs, request features, or contribute to the tool, you can do so directly through our azure-linux-image-tools GitHub repo. We welcome feedback and contributions from the community!

Acknowledgements

A huge thank you (in no order) to our Image Customizer team ─ Adit Jha, Brian Telfer, Chris Gunn, Deepu Thomas, Elaine Zhao, George Mileka, Himaja Kesari, Jim Perrin, Jiri Appl, Lanze Liu, Roaa Sakr, Kavya Nagalakunta and Vince Perri.