Microsoft releases Azure Linux 4.0 for Containers

Microsoft has released the public preview of Azure Linux 4.0, a new Linux distribution specifically optimized for container infrastructures. This Fedora-based variant is now available for the first time outside of Azure and can be downloaded as an ISO image from the project's GitHub page or found in the Azure Marketplace. The new version offers significant improvements for operation on virtualized servers, particularly regarding Azure Linux for VMs.

Technological Innovations with Kernel 6.18 LTS

At the heart of the release is the new Linux kernel 6.18 LTS, which provides numerous updated drivers and improved Hyper-V integration. These innovations enable native support for current GPUs and AI accelerators, optimizing the processing of compute-intensive tasks. Other components of the distribution include Glibc 2.42, OpenSSL 3.5.4, systemd 258.4, and Python 3.14.3, all contributing to the stability and security of the system.

Package management is handled by the powerful package manager dnf5, which is integrated into this version. Core tools such as Bash 5.3.9 and coreutils 9.7 are also included to ensure comprehensive functionality. The distribution is designed to provide a solid foundation for modern applications and container workloads.

Azure Container Linux for Maximum Security

In addition to the release of Azure Linux 4.0, Microsoft has announced Azure Container Linux (ACL). This extremely hardened host system is designed to function as an immutable operating system. System security is ensured through monthly security updates, allowing for continuous protection of Kubernetes environments.

To further reduce the attack surface, mechanisms such as Secure Boot and SELinux enabled by default are integrated. Additionally, a cryptographically secured supply chain is provided through a Software Bill of Materials (SBOM), offering extra security. These measures are part of Microsoft's strategy to maximize the security and stability of container workloads.

The use of the Fedora ecosystem allows Azure Linux 4.0 to benefit from a modern compiler toolchain. The familiar RPM package management and the dnf5 package manager provide developers and system administrators with an efficient way to install and manage software. These features make Azure Linux 4.0 an attractive option for companies looking to optimize their container infrastructures.

The release of Azure Linux 4.0 and Azure Container Linux demonstrates Microsoft's commitment to the advancement of container technologies. The distribution is now available as a public preview for Azure Virtual Machines, VM Scale Sets, and container base images, with no additional licensing costs. The ongoing FIPS 140-3 certification is expected to be completed soon, positioning the platform as a cost-effective solution for consolidating modern server architectures.