Getting Started with Windows Server 2025 Nodes in Kubernetes
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TechJunkie2023
Hey folks! I'm diving into using Windows Server 2025 nodes in my Kubernetes setup, and I've hit a snag. The Kubernetes docs mention that Windows Server versions newer than 2019 or 2022 should be compatible, but I'm encountering a persistent "host operating system does not match" error. I've tried different images like windows:ltsc2019, windows-server:ltsc2025, and windows-servercore:ltsc2025, but no luck. Interestingly, when I run the container using 'ctr' directly on the node, it works just fine. But, when I create a job with that image in Kubernetes, it throws a "HCS failed to create pod sandbox" error instead, indicating a mismatch. Even when I specify a build version like 'windows-build: 10.0.26100', Kubernetes says no nodes are available, despite them showing the same build number. I'm pretty much locked into using WS2025, so downgrading isn't an option. Has anyone else run into this or have any suggestions? Thanks!
Answers
Make sure to check your container network interface software; sometimes that can cause these kinds of mismatches with the host operating system.
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It sounds like WS2025 might just be too new. I suggest ensuring that everything is updated to the latest versions available, as that can often help with compatibility issues. Personally, I’ve been using a WS2022 node with a nanoserver:ltsc2022 image, and while it was tricky, it worked out for me eventually—especially after addressing network policies.
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Totally unrelated, but I'm curious why you’re going with a Windows node? Is it due to some legacy .NET Framework stuff you’re working with?
TechJunkie2023: That’s a good question! I'm currently helping a team set up a bare metal cluster for some exploratory work, but I believe the plan is to eventually transition to a Linux environment.
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I spent a lot of time setting up a Windows node from scratch using Microsoft's PowerShell scripts, but I faced a lot of issues. The networking kept degrading until the node was unusable after a couple of weeks. Plus, I couldn't get kubectl exec working from a Linux node to a Windows container, which was a slight nuisance. While I know Microsoft offers Windows nodes via Azure, I don’t think there's a reliable way for self-hosting at the moment.
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TechJunkie2023: That's a valid concern. I’m stuck with WS2025 for licensing reasons, but I fear it might not be supported yet…