Today at Microsoft Build, we're announcing the public preview of Azure Linux 4.0 - Microsoft's first party Linux distribution, purpose-built for Azure. Azure Linux 4.0 is available now for Azure Virtual Machines, VM Scale Sets, and container images – with Azure Kubernetes Service (AKS) support and Windows Subsystem for Linux (WSL) coming soon after.
Why Azure Linux
Running Linux on Azure often involves a mix of distributions - one for VMs, another for Kubernetes nodes, a third for container base images, and sometimes something different on developer machines. That flexibility is powerful, but it can also introduce operational overhead: multiple patch schedules to coordinate, multiple security baselines to validate, and more moving parts for SRE and security teams to stay ahead of. A more consistent baseline - especially one with a smaller footprint - can help reduce exposure and simplify day‑to‑day maintenance
Azure Linux was built with that principle in mind: a single, Microsoft-supported Linux foundation designed to work across every Azure compute surface. From kernel updates to CVE patches, Azure Linux is built and maintained by Microsoft with a predictable update cadence designed around Azure infrastructure. Azure Linux is included with Azure compute at no additional cost.
What Is Azure Linux 4.0
Azure Linux is a Fedora-derived, RPM-based Linux distribution built and maintained by Microsoft. It is open source, free to use, and optimized specifically for Azure. Minimal by choice, secure by default; Azure Linux ships only the packages required for cloud workloads. Azure Linux is built exclusively for cloud and server workloads, it is not intended to support desktop usage or GUI applications.
Azure Linux already powers millions of cores across Azure's internal services, including AKS, Azure SQL, Azure Cosmos DB, and many others. With 4.0, we're bringing the same OS - same security posture, same performance tuning, same operational simplicity - to every Azure customer.
When Azure Linux 4.0 reaches General Availability, you can expect seamless integration with the Azure services you already rely on, including:
- Microsoft Defender for Cloud - vulnerability assessment and threat detection
- Azure Monitor - telemetry, logs, and performance monitoring
- Azure Migrate - discovery and migration tooling
- Trusted Launch and Secure Boot - hardware-rooted security
- Azure Portal, CLI, ARM, Bicep, Terraform, Ansible -deploy and manage with your existing tools
What's New in Azure Linux 4.0
|
Component |
Version |
What Changed |
|
Kernel |
6.18 LTS |
Azure-tuned with new hardware drivers, improved Hyper-V integration, GPU/AI accelerator support |
|
Package Manager |
dnf5 |
Complete rewrite from python to reduce dependencies, faster package resolution, lower memory usage |
|
glibc |
2.42 |
This includes performance improvements in string ops, memory allocation, thread handling |
|
OpenSSL |
3.5 |
This release includes post-quantum cryptography support, improved QUIC support, and other crypto updates. |
|
systemd |
258 |
Faster boot sequences, improved service management |
|
Python |
3.14 |
JIT compiler, new syntax features |
|
RPM |
6.0 |
Modernized database backend, improved signature verification |
|
FIPS 140-3 |
In progress |
Will be available at GA. |
Azure Linux on Virtual Machines
Deploy Azure Linux 4.0 directly from the Azure Marketplace on any Azure VM or VM Scale Set. Azure Linux images are validated across Azure VM SKUs and tuned for Azure compute, storage, and networking delivering faster VM startup and provisioning with a reduced package footprint.
Whether you're running web applications, databases, or GPU-accelerated AI/ML workloads, Azure Linux provides a consistent, secure foundation with no additional OS licensing cost. You pay only for the underlying Azure compute resources.
Deploy your first Azure Linux VM in minutes from the Azure Marketplace.
Azure Linux on Azure Kubernetes Service
Azure Linux has been the container host for AKS since 2023, already powering mission-critical Kubernetes workloads at massive scale. With 4.0, we're also introducing Azure Container Linux (ACL) an immutable, container optimized variant for environments with stricter security and compliance requirements. To learn more about Azure Container Linux, see ACL blogpost.
|
Azure Linux (General purpose) |
Azure Container Linux (ACL) | |
|
Update model |
Package-based (dnf5) |
Image-based, immutable, auto-updating |
|
Customization |
Full package management |
Locked-down, minimal surface |
|
Best for |
General AKS workloads |
Regulated, high-security environments |
|
SELinux |
Supported |
Enforcing by default |
Both options share the same kernel, security update cadence, and Azure integration; fully supported by Microsoft, end to end.
Azure Linux Container Images
Build and run containerized applications on Microsoft-maintained base images from the same Azure Linux supply chain. One Linux experience from VMs to containers with the same security updates, same compliance posture, and same operational model.
|
Image Type |
Use Case |
|
Base |
Full flexibility - install any packages you need |
|
Runtime (Python, Node.js, Java, .NET) [Not available at Preview] |
Pre-configured for your language stack |
|
Distroless |
Minimal attack surface - no shell, no package manager |
All images are available on Microsoft Container Registry (MCR) and follow the same monthly security update cadence as Azure Linux VM images.
Azure Linux on WSL
Familiar Linux, optimized for Azure. Develop locally on the same Linux you run in production. Azure Linux for Windows Subsystem for Linux brings your production OS to your developer workstation, eliminating environment drift and giving your team a consistent dev-to-cloud workflow.
Azure Linux for WSL will be available shortly after Build.
Secure by Default, Backed by Microsoft
Security is not an add-on in Azure Linux; it's foundational. Built with security in mind from day one, Azure Linux applies defense-in-depth from the kernel through to the supply chain. A reduced package footprint means fewer vulnerabilities to manage, and Microsoft's ownership of the full supply chain enables fast-track CVE response. Below is a summary of security capabilities that you should expect to see in Azure Linux at the time of general availability.
|
Capability |
Details |
|
Secure Boot & Trusted Launch |
Signed shim, GRUB, kernel, and systemd-boot. |
|
SELinux |
Supported on all images. Enforcing by default. |
|
FIPS 140-3 |
Certification in progress. Built-in crypto module support. |
|
Kernel hardening |
ASLR, stack protection, seccomp, systemd service sandboxing. |
|
Supply chain security |
All packages and repos cryptographically signed. SBOMs published. |
|
Identity |
Entra ID SSH support. |
|
CVE response |
Microsoft-owned supply chain enables fast-track Critical/High CVE patches. |
|
Lifecycle |
LTS kernels maintained for lifetime of the distribution. |
Day-1 Ecosystem Partner Support
Azure Linux already has validated support from a broad ecosystem of security, monitoring, networking, and data partners via AKS and VM support:
- Dynatrace — Application performance monitoring and observability
- Aquasec – database platform support
- Qualys — Vulnerability management, compliance scanning, and asset inventory
- Isovalent — eBPF-powered networking, security, and observability via Cilium
- Elastic — Log analytics, infrastructure monitoring, and SIEM/XDR
- Upwind — Runtime cloud security and behavioral threat detection
- SAP — Enterprise workload certification for S/4HANA and NetWeaver
- Databricks — Data and AI platform powering lakehouse workloads at scale
- Arm — Native Arm64 architecture support for cost-efficient cloud compute
Proven at Scale
Azure Linux isn't new; it has been running production workloads at massive scale across Azure's internal services and early adopters.
Azure Linux has been powering production workloads at massive scale since 2022 across AKS, Azure SQL, Azure Cosmos DB, and other core Azure services along with LinkedIn and Databricks. With version 4.0, we're building on that proven foundation with a modernized stack, expanded compute surface support, and a new Fedora-derived base, bringing the same reliability our internal services depend on every Azure customer.
Databricks
Databricks migrated over 100,000 VMs and more than 1 million CPU cores to Azure Linux with zero customer-facing incidents. The migration eliminated separate hardened images by leveraging Azure Linux's built-in FIPS support and delivered measurable performance gains: 27% faster image pull times and approximately 5% faster query execution across their serverless compute fleet.
LinkedIn completed a major stack upgrade, migrating to Azure Linux 3 across their infrastructure. The transition enabled adoption of configuration as code and modern kernel integration, resulting in a more resilient, secure, and future-proof environment. LinkedIn's Grid team reported significant performance improvements following the migration.
Predictable Lifecycle and Updates
Patch faster. Operate simpler. Azure Linux follows a clear, predictable lifecycle designed for teams running large Azure fleets:
- LTS kernel - Maintained with monthly CVE backports.
- HWE kernels - Introduced annually for new hardware platforms, GPU, and AI accelerator enablement.
- Predictable updates - Packages (language runtimes, tools) are refreshed in predictable windows. Between windows, only critical/high CVE patches are backported.
- Monthly security updates - Predictable cadence for all supported packages.
For full details on the lifecycle model, kernel tracks, and package tiers, see the Azure Linux Release Cadence and Lifecycle documentation.
Get Started
Azure Linux 4.0 is available now in public preview. Choose the path that fits your workload:
|
Scenario |
How to Start |
|
Azure Virtual Machines |
Deploy from Azure Marketplace via Portal, CLI, ARM, Bicep, or Terraform |
|
Azure Kubernetes Service [Not available at Preview] |
Set --os-sku to AzureLinux when creating a node pool |
|
Container Images |
Pull from Microsoft Container Registry (MCR) |
|
WSL [Not available at Preview] |
wsl --install -d AzureLinux |
Learn More
- //Build Session: Build, deploy, and run Linux workloads on Azure
- Azure Linux documentation
- To learn more and get started, visit aka.ms/AzureLinuxProduct
- Azure Linux on GitHub
- Release notes
- Joining the ISV partner program: AzureLinuxPartners@microsoft.com
We're excited to put Azure Linux in your hands. Try it today and let us know what you think.