Rocky Linux Overview: Key Details and Considerations

For folks considering CentOS alternatives, Rocky Linux has been living in the spotlight. As a drop-in replacement for CentOS Linux (not to be confused with CentOS Stream) Rocky Linux has all the appearances of being a spiritual successor to CentOS Linux.

But for enterprise organizations, adopting a new distribution like Rocky Linux raises a number of questions. Will it be reliable? How will it be supported? What does the community look like? What do we need to consider before migrating? To help answer some of these questions, we put together an overview of Rocky Linux, including how it compares to CentOS, support and migration considerations, and the current status of Rocky Linux repositories.

What Is Rocky Linux?

Rocky Linux, the brainchild of CentOS founder Gregory Kurtzer, is a free, 100% bug-for-bug compatible fork of Red Hat Enterprise Linux 8 developed by the Rocky Enterprise Software Foundation.

Rocky Linux's "Rocky" 

In addition to Gregory Kurtzer, the CentOS Project was cofounded by Rocky McGaugh who has since passed away. In memory of Rocky, Greg decided to name this new distribution after him:

"Thinking back to early CentOS days... My cofounder was Rocky McGaugh. He is no longer with us, so as a H/T to him, who never got to see the success that CentOS came to be, I introduce to you...Rocky Linux" — Gregory Kurtzer, Founder of Rocky Linux

Rocky Linux Licensing

Licensing of Rocky Linux itself is 3-Clause BSD but, because Linux distributions are a collection of packages, each package may have its own licensing.

Who Should Use Rocky Linux?

Anyone who switched, or consider switching, to CentOS Linux 8 and doesn’t want to deal with the extra overhead of switching to CentOS Stream 8 should consider Rocky Linux 8 as a potential candidate for their infrastructure.

Rocky Linux Support Outlook

Rocky Linux 8 is a downstream rebuild of RHEL 8 and, as such, aligns with the RHEL 8 lifecycle and therefore will be actively maintained until 2029.

There are several options regarding support for Rocky Linux. Official support is offered by CIQ, another company founded and owned by Mr. Kurtzer and comprised of many of the same people who are intimately involved with Rocky Linux, but the RESF has stated that anybody can provide support for Rocky Linux.

Get Technical Support for Rocky Linux

OpenLogic provides technical support for the most popular Enterprise Linux distributions, including Rocky Linux. This allows our customers to engage with a single point of support for homogenous, heterogenous or hybrid OS deployments. Interested in learning more about how we can support your Rocky Linux deployments?

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Rocky Linux Migration Considerations

If you are planning or conducting an migration to Rocky Linux, there are a number of considerations to keep in mind.

• Be careful if your company has customized any OS packages as the migration script will perform a distro-sync which will replace any packages with the version in the Rocky Linux repos, regardless of whether the repo version is newer or older than the installed version.
• SecureBoot is not available with Rocky Linux. This is a common problem for new distributions due to choreographing the keys, certs and hardware/hypervisor vendor support. Since RHEL and CentOS support SecureBoot, be sure to verify whether or not your infrastructure relies on SecureBoot before attempting to migrate your systems.
• At this time, x86_64 is the primary architecture supported, but aarch64 (ARM64) ISOs and packages are also available.  In the future, ppc64le support may become available, but it is not presently a priority.
• If your systems are still viable candidates for migrating to Rocky Linux, the migrate2rocky.sh script can make migrations from other EL8 variants rather easy. Most RHEL8-based OSs can be migrated but if those systems are registered with Katello, Uyuni or SUSE Manager, they cannot be migrated using this tool. The migration script even checks to see if the systems currently have SecureBoot enabled and suggest disabling SecureBoot to proceed.

Get Support for Your Rocky Linux Migration

Need help performing your migration to Rocky Linux? Talk to an expert today to see how we can make your migration a success.

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Rocky Linux Repositories

As of early August 2021, Rocky Linux has almost 100 mirrors, including a global CDN (Content Delivery Network). Over 80 mirrors provide HTTP, over 80 mirrors provide HTTPS and over 50 provide RSYNC connections.

Secure communication with the repos over HTTPS is not strictly necessary since no authentication is required to access the repos. Utilizing HTTPS will cause proxies to not be able to cache the packages. Certain proxies (like squid) can be configured to accept HTTP requests from the client and connect to the upstream repos via HTTPS, though.

RSYNC access is primarily useful if you’d like to create your own local mirror to distribute the RPMs to your clients. A caching proxy or local mirror is something that I recommend for most of our customers, not just for the packages published by the OS vendor (Rocky Linux, in this case), but also for 3rd party application repos or private repositories like we provide for our customers.

When the Rocky Linux repositories were first populated, signed repository metadata was not provided. This changed around July 11, 2021 with the inclusion of GPG signed metadata. With the latest update to the libdnf package, you can set repo_gpgcheck=1 in your DNF configuration to verify the repo metadata via GPG.

Rocky Linux has just started offering errata with their updates. This means commands like dnf updateinfo list --security --available and

dnf upgrade --cve CVE-20xx-xxxx will work in Rocky Linux! (CentOS users have been wanting this feature for a very long time.)

# dnf updateinfo list --security --available
RLSA-2021:2714 Important/Sec. bpftool-4.18.0-305.10.2.el8_4.x86_64
RLSA-2021:2570 Important/Sec. bpftool-4.18.0-305.7.1.el8_4.x86_64
RLSA-2021:2714 Important/Sec. kernel-4.18.0-305.10.2.el8_4.x86_64
RLSA-2021:2570 Important/Sec. kernel-4.18.0-305.7.1.el8_4.x86_64
RLSA-2021:2714 Important/Sec. kernel-core-4.18.0-305.10.2.el8_4.x86_64
RLSA-2021:2570 Important/Sec. kernel-core-4.18.0-305.7.1.el8_4.x86_64
RLSA-2021:2714 Important/Sec. kernel-modules-4.18.0-305.10.2.el8_4.x86_64
RLSA-2021:2570 Important/Sec. kernel-modules-4.18.0-305.7.1.el8_4.x86_64
RLSA-2021:2714 Important/Sec. kernel-tools-4.18.0-305.10.2.el8_4.x86_64
RLSA-2021:2570 Important/Sec. kernel-tools-4.18.0-305.7.1.el8_4.x86_64
RLSA-2021:2714 Important/Sec. kernel-tools-libs-4.18.0-305.10.2.el8_4.x86_64
RLSA-2021:2570 Important/Sec. kernel-tools-libs-4.18.0-305.7.1.el8_4.x86_64
RLSA-2021:2569 Moderate/Sec.  libxml2-2.9.7-9.el8_4.2.x86_64
RLSA-2021:2575 Moderate/Sec.  lz4-libs-1.8.3-3.el8_4.x86_64
RLSA-2021:2569 Moderate/Sec.  python3-libxml2-2.9.7-9.el8_4.2.x86_64
RLSA-2021:2714 Important/Sec. python3-perf-4.18.0-305.10.2.el8_4.x86_64
RLSA-2021:2570 Important/Sec. python3-perf-4.18.0-305.7.1.el8_4.x86_64
RLSA-2021:2574 Moderate/Sec.  python3-rpm-4.14.3-14.el8_4.x86_64
RLSA-2021:2574 Moderate/Sec.  rpm-4.14.3-14.el8_4.x86_64
RLSA-2021:2574 Moderate/Sec.  rpm-build-libs-4.14.3-14.el8_4.x86_64
RLSA-2021:2574 Moderate/Sec.  rpm-libs-4.14.3-14.el8_4.x86_64
RLSA-2021:2574 Moderate/Sec.  rpm-plugin-selinux-4.14.3-14.el8_4.x86_64
RLSA-2021:2574 Moderate/Sec.  rpm-plugin-systemd-inhibit-4.14.3-14.el8_4.x86_64
RLSA-2021:2717 Important/Sec. systemd-239-45.el8_4.2.x86_64
RLSA-2021:2717 Important/Sec. systemd-libs-239-45.el8_4.2.x86_64
RLSA-2021:2717 Important/Sec. systemd-pam-239-45.el8_4.2.x86_64
RLSA-2021:2717 Important/Sec. systemd-udev-239-45.el8_4.2.x86_64

Rocky Linux Release Lag

Let’s examine the release lag for updates posted since Rocky Linux went GA. Here’s what I’ve seen with a cursory evaluation. There were a large number of updates published by Red Hat on June 29th and taking a look at a sample of these shows that Rocky Linux published their updates the same day.

Since June 29th, there have been 8 security updates and 4 bugfix updates for RHEL packages present in Rocky Linux:

• All 8 security updates were released within 24 hours
• 2 bugfix updates were released within 24 hours
• 1 bugfix update was released within 2 days
• 1 bugfix update was released within 3 days

I think that this demonstrates that security updates are a priority for the Rocky Linux Release Engineering Team and that Rocky Linux users will not have to wait long to receive them. OpenLogic will continue to monitor the release lag of Rocky Linux (and other CentOS alternatives) as package updates are published and new point releases materialize.

Rocky Linux vs. AlmaLinux

Both Rocky Linux and AlmaLinux are downstream RHEL rebuilds that emerged in response to the Red Hat announcement on Dec 8, 2020 that CentOS Linux was being discontinued.

For some background, Red Hat stated that CentOS Linux 8 will now have a diminished lifecycle that will go end of life (EOL) in December of 2021 — 8 years earlier than previously announced. CentOS Linux 6 went EOL on Nov 30, 2020 (as scheduled) and CentOS Linux 7 has not received any change in EOL at this time.

With both projects coalescing to fill the same vacuum that will be left by CentOS 8, both should be relatively identical. Not only to each other, but to the upstream RHEL release that they are rebuilt from.

Where we expect to see differences is in release lag, responsiveness to bug reports, communication and transparency of the project leads.

See our comparison of Rocky Linux vs. AlmaLinux >>

Rocky Linux vs. CentOS Linux

Rocky Linux 8 is intended to be a drop-in replacement for CentOS Linux 8.

As mentioned above, Rocky Linux is providing update errata! The updateinfo metadata is provided, which means you can perform security-centric package management such as installing only security-only updates, query for patched vulnerabilities, etc. CentOS Linux does not provide the updateinfo metadata, but up until CentOS 7, package announcements were available via a mailing list. CentOS 8 doesn’t have the updateinfo metadata, either, and even the package announcements on the CentOS-announce mailing list are absent.

Rocky Linux vs. CentOS Stream

The entire reason that Rocky Linux exists is to fill the void that will exist when Red Hat terminates CentOS Linux 8 in Dec 2021. You can be assured that Rocky Linux will not contain the newest versions of the packages shipped with CentOS Stream. This is by design. If an upstream distribution like CentOS Stream fits your business and technical models, then CentOS Stream should be available for many years to come.

Final Thoughts

Rocky Linux appears to be gaining acceptance at a rapid pace. Stats from our OpenLogic image usage show that our Rocky Linux images are launched as much as (or more than) the other Enterprise Linux distribution images that we publish, including CentOS.

If you’re interested in trying out Rocky Linux, OpenLogic has several images published that you can try out, including our Vagrant boxes, AWS images, GCE images, and Azure images. 

Need Support for Your Rocky Linux Deployments?

If you're working with Rocky Linux, OpenLogic can provide the expert technical support and services you need to succeed in the enterprise. Talk to an expert today and see how we can support your goals.

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Additional Resources

• Blog – Planning a CentOS to Rocky Linux Migration
• Blog - AlmaLinux vs. Rocky Linux: Exploring the Key Differences
• Blog - What's New in AlmaLinux 9
• Blog - RHEL 9 Release Overview
• Blog - What to Expect in Rocky Linux 9
• Blog - What Happened to CentOS and What to Do Next
• Blog - Finding the Right Linux Distribution for Your Organization
• Blog - CentOS Stream Pre-Flight Checklist
• Blog - What's Next for CentOS Stream
• Webinar Series - Discussing the Future for CentOS