microsoft has made available downloadable ISO files for Azure Linux 4, a distribution derived from Fedora. This allows users to install and test it outside of Azure for the first time.
The ISO files can be found on the project page. GitHub page. Azure Linux 4 is still in preview and Microsoft discourages its use in production environments. x86-64 and Arm64 images are offered.
The ISO files are not found in the usual GitHub Releases section, which mainly includes kernel builds. Instead, users should scroll down to the Using Azure Linux section and expand the ISO Installer subsection to find the images.
What Azure Linux 4 is designed for
Azure Linux 4 is the successor to Azure Linux 3, which in turn evolved from Microsoft’s previous CBL-Mariner distribution. Unlike its predecessors, which were based on VMware Photon OS, Azure Linux 4 gets most of its packages and metadata from Fedora. As part of the transition, Microsoft has changed configuration files from the .spec format to the TOML format.
The current build is identified as “Four Beta” and runs on kernel 6.18 with systemd 258.4. Although derived from Fedora, Azure Linux 4 does not support Fedora packages. Only two repositories are enabled by default:
- azurelinux base
- azurelinux-microsoft, both hosted at packages.microsoft.com/azurelinux/.
The selection of packages available is limited; Common tools such as less and htop are not included in the default installation and are not available for installation.
Azure Linux 4 is designed to be used inside Azure virtual machines as part of automated deployment pipelines. The ISO version is primarily for testing and is not intended for general desktop or basic installation.
The distribution does not come with a graphical desktop environment like GNOME and Microsoft has not announced plans to include one. Users who want a container-centric host should consider Azure Container Linux, which is Microsoft’s dedicated distribution for the Azure Kubernetes service. It is available separately on GitHub.
What to expect from the ISO preview
The Azure Linux 4 preview has modest resource requirements. It has a download size of 1 GB, requires 1.1 GB of disk space and 359 MB of RAM.
The installation process is simple and uses a simple command line tool. By default, it sets an LVM configuration with memory expansion enabled.
This distribution can run inside on-premises Hyper-V virtual machines as well as Azure virtual machines, making it accessible to developers testing workloads before deploying them to Azure infrastructure.
Azure Linux 4 includes the dnf package manager, which allows users to easily install additional software from available repositories. The distribution is not intended to be an immutable container host, meaning administrators have the flexibility to customize their installations for specific workloads within the range of available packages.
Microsoft has not published a detailed roadmap for the package and the current repository selection reflects the release preview status.
How to try Azure Linux 4 locally
To download and try Azure Linux 4 locally, follow these steps:
- Visit the Azure Linux 4 GitHub page and scroll down to the section titled “Using Azure Linux.”
- Expand the ‘ISO Installer’ subsection and choose x86-64 or Arm64 image depending on your needs.
- Create a virtual machine using Hyper-V, VirtualBox, VMware, or another hypervisor.
- Boot the virtual machine from the ISO file you downloaded and continue with the command-line installation prompts.
It is important to note that Azure Linux 4 is still in preview, so it should not be used in production environments. The preview status indicates that the distribution may have bugs, incomplete package selections, or behaviors that could change before it is generally available.
Lifecycle documentation published by Microsoft indicates that Azure Linux 4 will use long-term support kernels and receive monthly security updates. Some reports have mentioned a two-year update cycle, but this has not been confirmed in the official lifecycle documentation.
Azure Linux 4 illustrates Microsoft’s continued effort to bring more of its infrastructure toolchain in-house. The company migrated LinkedIn to Azure Linux two years ago, removing its dependence on the CentOS Linux distribution, which has now reached end of life.
Moving to Fedora as an upstream source with Azure Linux 4 reduces another dependency on VMware Photon OS, which was used in previous versions.
This transition also supports a broader industry trend away from Broadcom’s VMware, with companies such as Tesco and T-Mobile also reportedly moving their infrastructure away from VMware.
What users should know before installing
For users interested in trying out Azure Linux 4, ISO downloads offer the first opportunity to try out the distribution locally. It is recommended to download and test only in a virtual machine environment.
Use it to evaluate packaging and configuration changes from previous versions of Azure Linux.
Do not use it for production workloads or mission-critical systems. Keep an eye on the GitHub repository for updates as the preview moves toward general availability.
Microsoft has not announced a specific release date for Azure Linux 4. Users planning to migrate from Azure Linux 3 should follow the preview on GitHub and consult Microsoft’s official documentation for guidance on when it will be ready for production.
