title: Microsoft has free and open-sourced a Linux operating system — yes, it's made by Microsoft itself date: 2026-06-29 platform: wechat-mp status: finalized cover: cover.png

Microsoft has free and open-sourced a Linux operating system, that's right! It's a Microsoft product

June 2026

💡 What You Will Learn

title: Microsoft has free and open-sourced a Linux operating system — yes, it's made by Microsoft itself date: 2026-06-29 platform: wechat-mp status: finalized cover: cover.png Microsoft has free and

📜 Table of Contents

• 1. What Is Azure Linux 4.0?
• 1. It's Not Like Ubuntu / Fedora / Mint
• 2. Its Lineage — Fedora 43
• 3. What Did Microsoft Actually Build?
• 2. How Hardcore Is the Tech Stack? A Bunch of Latest Versions
• 1. OpenSSL 3.5 + Post-Quantum Cryptography
• 2. Python 3.14 + JIT
• 3. FIPS 140-3
• 3. Who's Already Using It?
• 4. Why Is Microsoft Doing This?
• 5. Azure Container Linux Released Alongside
• 6. Does It Matter to Regular People?
• 7. If You Want to Try It
• 8. Final Thought

title: Microsoft Open-Sources a Linux OS It Built Itself date: 2026-06-29 platform: wechat-mp status: finalized cover: cover.png

Microsoft Open-Sources a Linux OS — Yes, It's from Microsoft

In June 2026, at its Build 2026 developer conference, Microsoft officially unveiled a Linux distribution to the public — free, open-source, free to download, and ready to use.

When you hear "Microsoft makes Linux," your first reaction is probably, "Wait, wasn't Microsoft always trashing Linux?"

Exactly. But this time, they actually did it — Azure Linux 4.0 is now fully open-sourced on GitHub. Anyone can install it, modify it, and even use it commercially.

A company that once treated Linux as its enemy is now giving away a Linux OS it built itself. That alone is the biggest plot twist in tech this year.

Let me break it down for you — what this Microsoft-made Linux actually is, why they made it, and whether it matters to regular people.

1. What Is Azure Linux 4.0?

In one sentence: It's Microsoft's "homegrown cloud server OS," now open to the public.

But it's not the kind of Linux you'd install on a laptop as a daily driver.

Let me unpack that —

1. It's Not Like Ubuntu / Fedora / Mint

The Linux distros most people know (Ubuntu, Fedora, Debian, Mint) are all general-purpose — you can install them on your laptop, they have desktops, icons, and you can watch videos and listen to music.

Azure Linux 4.0 is not that.

It has no desktop, no GUI, no graphical interface. After installation, all you see is a black screen with white text — a command-line terminal, just like DOS from 30 years ago.

It's only for cloud servers, virtual machines, containers, and Kubernetes — the internet infrastructure you can't see but use every single day.

2. Its Lineage — Fedora 43

Azure Linux 4.0 is built on the Fedora 43 kernel — Fedora is one of the most mainstream distros in the Linux world (backed by Red Hat).

This means: - Package format is RPM (same as Fedora and Red Hat) - Full ecosystem compatibility with the Red Hat family (zero learning curve for anyone who's used RHEL)

3. What Did Microsoft Actually Build?

Microsoft didn't just slap a logo on Fedora and call it Azure Linux.

Azure Linux 4.0 is designed with a "cloud-server-only" goal —

The key thing to look at is image size — Azure Linux is just 300 MB. Half the size of Ubuntu.

Why so small? Because it only includes the minimal set needed for cloud servers — no audio, no desktop, not even less is bundled. Smaller attack surface, fewer vulnerabilities, faster patches.

This is what a "cloud-native OS" should look like — an invisible operating system that works silently, and you never even notice it's there.

2. How Hardcore Is the Tech Stack? A Bunch of Latest Versions

Let me just throw the raw data at you (source: Microsoft official + GitHub repo):

A few things worth calling out:

1. OpenSSL 3.5 + Post-Quantum Cryptography

This is a big deal.

OpenSSL 3.5 ships with quantum-resistant encryption algorithms (CRYSTALS-Kyber for key exchange + CRYSTALS-Dilithium for digital signatures). These are the new-generation standards NIST just finalized in 2024.

What this means is — when future quantum computers can crack traditional RSA encryption (industry estimates say within 10-20 years), Azure Linux won't be the weak link.

For enterprise customers (government, finance, healthcare) with strict compliance requirements, this is a very hard requirement.

2. Python 3.14 + JIT

Python 3.14 is the stable release from October 2025, and it's the first to officially introduce JIT (Just-In-Time compilation).

Traditional Python is interpreted — slow. JIT compiles as it runs — a massive boost for Python-heavy workloads like AI inference and data processing.

Azure Linux 4.0 ships Python 3.14 out of the box, so developers don't have to set it up themselves.

3. FIPS 140-3

FIPS 140-3 is the US government's mandatory cryptographic module certification standard — for finance, healthcare, and government clients working on government projects, FIPS is a hard gate.

Azure Linux 4.0 is still "in progress" — the certification will be in place by the time it hits GA (General Availability).

For enterprise compliance, this is a real signal.

3. Who's Already Using It?

This is the strongest evidence —

Azure Linux isn't some new "experiment" Microsoft just cooked up.

It's been used internally for 7 years — starting as the internal project CBL-Mariner (Common Base Linux Mariner) in 2019, renamed to Azure Linux in March 2024, and now opened to the public.

Major customers already on it:

• ✅ LinkedIn — entire infrastructure fully migrated to Azure Linux 3. A social platform with 300 million monthly active users globally.
• ✅ Databricks — 100,000 VMs and 1M+ CPU cores all running on Azure Linux. Zero customer-visible incidents.
• ✅ Microsoft itself — core cloud services like AKS (Azure Kubernetes Service), Azure SQL, and Azure Cosmos DB all run on Azure Linux.

An OS that carries all of LinkedIn plus most of Databricks' business — now free for you to use.

Still wondering if it's stable?

4. Why Is Microsoft Doing This?

Self-interest. Very straightforward business logic.

The number of Linux VMs running on Azure has already surpassed Windows Server. In other words — most customers on Microsoft's cloud are using Linux.

But whose Linux? Ubuntu (Canonical's), RHEL (Red Hat's), SUSE (SUSE's), Debian (the community's)…

All someone else's OS. Microsoft only makes money on infrastructure (compute, storage, networking) — it gets zero share of the OS subscription fees.

Example: A customer runs Red Hat Enterprise Linux on Azure — every single VM pays a subscription fee to Red Hat. That money has nothing to do with Microsoft.

If Azure Linux 4.0 takes off —

✅ Microsoft controls the entire stack — hardware, virtualization, OS, monitoring, patching, supply chain… one vendor, full accountability ✅ OS subscription revenue stays in its own pocket ✅ Security responsibility is clearer — customers deal with just Microsoft, no more finger-pointing between Canonical + Red Hat + SUSE ✅ Compliance advantage — Microsoft can promise "full-stack SBOM (Software Bill of Materials) from hardware to OS" — the selling point finance/government customers love most

Same logic — Amazon did this 10 years ago (Amazon Linux), Google did it (Container-Optimized OS), Alibaba Cloud did it (Anolis OS) — Microsoft is just filling in the gap now.

It's not charity. It's business.

5. Azure Container Linux Released Alongside

Quick side note — at Build 2026, Microsoft also released a second Linux product — Azure Container Linux.

It looks similar to Azure Linux 4.0, but the philosophy is completely different —

Azure Container Linux has been silently running underneath AKS since 2023, and now it's finally released as a standalone product.

6. Does It Matter to Regular People?

Honest answer: Not in the short term.

Azure Linux 4.0 is currently in public preview, explicitly marked "not for production use."

If you: - Use Ubuntu / Fedora / Mint on your laptop → completely unaffected - Use RHEL / Debian on servers → completely unaffected - Use WSL (Windows Subsystem for Linux) as a developer → unaffected in the short term (a WSL version of Azure Linux is coming soon)

But —

It reveals a trend:

In the cloud computing era, operating systems are a "commodity," but "cloud-native + enterprise-grade security" is the scarce resource.

With Azure Linux 4.0, Microsoft is setting an example for every cloud vendor — "Your cloud deserves an OS you built yourself."

For developers, Azure Linux 4.0 will eventually land in WSL, meaning you can write code and run containers on your Windows laptop, then deploy seamlessly to Azure Linux in production — the environment consistency problem is completely gone.

That significance is ten times bigger than "just another Linux distro."

7. If You Want to Try It

The source code and documentation are all open on GitHub:

https://github.com/Microsoft/azurelinux

Download the ISO, spin up a VM with VirtualBox or Hyper-V, and you're good to go.

But after you install it, you'll see —

A black screen with white text, waiting for a username. No GUI, no desktop, no onboarding wizard.

Don't panic — enter your username and password, and you're in bash.

This is what a cloud-native OS looks like. No GUI, because GUIs are for "people"; Azure Linux is for "machines."

8. Final Thought

A company that once treated Linux as its enemy is now giving away a Linux OS it built itself.

This isn't Linux's victory, nor Microsoft's surrender.

It's the triumph of business logic in the cloud computing era — whoever controls the OS, controls the cloud.

And Microsoft just filled in that final piece of the puzzle.

That's it for today.

If you found this useful, hit like, bookmark, and share — give me that triple tap, so I know this series is worth continuing.

Drop a comment below:

• What do you think of Microsoft's move here? Genuine embrace of open source, or just a "I want it all" business play?