What makes Fedora CoreOS container optimized?

Guys, I am probably asking a stupid question right now. But I really don’t get why FCOS is “container optimized”. Why is that? What features make it container optimized?

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This came up recently in the matrix channel too:

It’s mostly just “batteries included with everything you need to run containers” and also “CI tested to make sure basic container functionality works” before shipping.


This is one of the things that triggered my suggestions in a recent thread to drop moby-engine (aka docker) from the default image and just leave podman.

The moby-engine package is lacking active maintainers and new volunteers, and has security vulnerabilities from October 2023. This happens sometimes for community-driven operating systems, but when it happens for Docker on a “container optimized” OS then something doesn’t feel quite right (ie, can an OS really claim to be container optimized when it ships a poorly maintained Docker?).

(NB: Not pointing any fingers, just discussing the situation.)

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I think to take this suggestion to the next level an issue would have to be opened against Issues · coreos/fedora-coreos-tracker · GitHub and tagged with the meeting label so we can discuss at our weekly community meeting, which is the place where things like this get decided.

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It’s good but is there some more detailed information? Like official docs

Because I am not quite sure what is “everything I need to run containers”

Thanks so much for pointing me there @dustymabe !

I’ve opened this feature request. Could you kindly add the meeting label? I don’t think I have permission to do that.

How about two different container runtimes?

Running through our tutorials are a great way to run through some example workflows that might help show things off.

Ye but does this thing makes OS “container optimized”? I can install two different container runtimes on ubuntu and run tests to make sure everything is working but I don’t think this will make my ubuntu “container optimized” :slight_smile:

Fedora CoreOS is primarily designed to serve as an operating system on Kubernetes nodes and is the upstream basis for RHEL CoreOS, which is the default operating system for all OpenShift Container Platform cluster machines. Here is a list of projects actively using Fedora CoreOS.

I think you’re just trying to pick with nit’s here. You were given the explanation as to why FCOS claims to be container optimized. Yes you can setup up Unbuntu to also be container optimized, but with FCOS you don’t have to, what’s needed is already integrated and installed after quality testing.


The “container optimized” statement sounds too serious for me and because of that I want to get more detailed answers

In what way?

Have you tried that? Have you set up, using available documentation, a containerized workflow for development? Or for Kubernetes purposes? I think an appreciation of the claim by FCOS would come from such an exercise.

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