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      CoreOS Container Linux Alternatives

       

       

       

       

      Yes, it’s true.

       

      Six years since the first CoreOS release, our favorite container-optimized operating system has reached end-of-life.

       

      So what are your options?

       

       

       

    • Clearly, if you are using CoreOS today, or are looking for a container-optimized Linux, you need to make a plan. But what are your options? Let's look at the alternatives and the facts you need to make that plan, depending on your use case and needs. Check out the leading CoreOS Container Linux alternatives below, or jump straight to our summary and conclusion.

    • So what options are available to you?

      Fedora CoreOS

      Fedora CoreOS is Red Hat’s official successor to CoreOS Container Linux. However, it is not a simple continuation of the original CoreOS: it is rather a merging of the former Red Hat Atomic Host with CoreOS Container Linux, with some key differences you should understand.

      Flatcar Container Linux

      Flatcar Container Linux is a “friendly fork” of CoreOS Container Linux, so is essentially identical. Maintained by Kinvolk, a company that worked closely with CoreOS in the early days, Flatcar is so close to CoreOS that in-place updates are practically seamless.

      Red Hat Enterprise Linux CoreOS

      Red Hat Enterprise Linux CoreOS (RHCOS) is Red Hat’s flagship container-optimized operating system. It is based on Fedora CoreOS, with each release subject to additional hardening/testing, and integration with OpenShift.

      AWS Bottlerocket

      Bottlerocket is a new offering in the container-optimized Linux space, from Amazon Web Services (AWS). It follows a lot of the CoreOS philosophy — minimal OS for container workloads with automatic atomic updates — but is primarily targeted at AWS's EC2 environment and EKS Kubernetes offering.

    • Summary

      See how the leading CoreOS Container Linux alternatives stack up against each other, or scroll down to the conclusion if you just want to get to the bottom line.

      Fedora CoreOS

      Pros:

      • Comes from Red Hat
      • Active project
      • Available on wide range of platforms

      Cons:

      • Larger distro
      • No in-place update
      • No support for cloud-init
      • Many configuration changes
      • Not hardened for production by Red Hat - releases may not be fully tested compared with RHEL CoreOS
      • Relatively new project (out of preview in January 2020)
      • No commercial support available

      Flatcar Container Linux

      Pros:

      • Seamless migration from CoreOS Container Linux
      • Identical operational experience to CCL
      • Small footprint
      • Established project (>2 years)
      • Available on wide range of platforms
      • LTS channel available for stable production environments

      Cons:

      • Backed by a smaller company than Red Hat / AWS

      RHEL CoreOS

      Pros:

      • Well integrated with OpenShift
      • Hardened for production by Red Hat
      • Available on wide range of platforms

      Cons:

      • Only supported as part of an OpenShift subscription
      • Otherwise, as for Fedora CoreOS

      AWS Bottlerocket

      Pros:

      • Supported by AWS in EC2
      • Well integrated with EKS

      Cons:

      • Only available for AWS today
      • No official support for users of non-AWS platforms
      • Very new project, not yet field hardened

    • Conclusion

      And the winner is…

       

      All of them!


      There is no single "bottom line" because the path you choose depends on your needs and use case.

       

      Instead, here are some recommendations based on some common scenarios.

    • Recommendations

      If you are using Red Hat OpenShift

      …then you should use RHEL CoreOS: it is bundled with your existing subscription, and fully integrated and supported.

      If you want a seamless in-place upgrade for an existing CoreOS Container Linux deployment

      …then Flatcar Container Linux is the only solution meeting your needs today.

      If you want to try a cutting-edge operating system with the latest features, and are willing to live with occasional regressions or breaking changes and best-efforts community support (rather than a commercial support contract)

      …then consider either Fedora CoreOS or Flatcar Container Linux. Both are good solutions.

      If you want a container-optimized operating system with enterprise support AND you’re not using Red Hat OpenShift

      …then you should use Flatcar Container Linux with a support subscription from Kinvolk. It is the only solution offering that capability today.

      If you will only deploy on AWS, want an OS that is backed up by Amazon, and are willing to try something that’s not yet a stable, generally available release

      … then Bottlerocket may be worth a look for you. However, Fedora CoreOS or Flatcar Container Linux will both give you essentially the same functionality, but with a more mature project and from platform-neutral project teams.

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