How CentOS Became CentOS Stream, and Why Rocky Linux Exists Because of It

On December 8, 2020, the CentOS Project announced that its focus would shift from CentOS Linux—the downstream rebuild of released Red Hat Enterprise Linux content—to CentOS Stream, positioned just ahead of a current RHEL release. The disruptive part was not only direction: CentOS Linux 8 updates would stop on December 31, 2021, years earlier than users had planned, and there would be no CentOS Linux 9.

Rocky Linux and AlmaLinux emerged in direct response, but CentOS Stream was not simply CentOS Linux renamed.

CentOS Stream already existed

Red Hat introduced CentOS Stream in September 2019 as a continuously delivered development stream between Fedora and upcoming RHEL minor releases. Fedora remained where broader innovation for future major RHEL versions began; Stream exposed and accepted work closer to the next RHEL minor-release content.

The December 2020 announcement made Stream the CentOS Project’s future focus. Describing that event as the creation of Stream erases its first year; describing Stream as an unstable nightly branch ignores its defined place in RHEL engineering.

CentOS Linux and Stream occupied opposite sides of RHEL releases

CentOS Linux rebuilt sources corresponding to already released RHEL packages after removing/replacing Red Hat branding and performing project integration. It aimed at functional/binary compatibility but did not include Red Hat subscriptions, certifications or support.

CentOS Stream receives changes before they enter a subsequent RHEL minor release. That gives hardware/software partners and community contributors earlier visibility and a contribution point. It is a different risk/change model from consuming a rebuild after RHEL release.

The open-source licenses in RHEL packages require source obligations according to each license and distribution recipient; they do not reduce the entire product/history to “Red Hat must publish every source publicly in one particular repository forever.” CentOS’s rebuild process depended on source availability plus substantial release engineering.

The lifecycle shock centered on CentOS Linux 8

CentOS Linux 8 had launched in September 2019 with expectations aligned to a long RHEL 8-era lifecycle. The 2020 decision shortened its update window to December 31, 2021. Organizations that had just migrated from CentOS 7 faced another OS migration within roughly a year.

The announcement did not end every CentOS Linux release immediately. CentOS Linux 7 retained its stated path through June 30, 2024; CentOS Linux 6 had ended November 30, 2020. The exact matrix matters when reconstructing incident/change plans.

Red Hat’s stated rationale was an open RHEL development path

Red Hat argued that maintaining both a downstream rebuild and Stream split project attention, while Stream let partners/community influence upcoming RHEL minor releases. The CentOS Governing Board participated in the shift according to the announcement/FAQ.

Critics focused on governance and reliance: the same sponsor that had joined forces with CentOS in 2014 could change the rebuild’s schedule after users deployed it. Both facts belong in the record; attributing the decision solely to technical merit or solely to malice is not evidence.

Rocky Linux was announced as a replacement effort

Gregory Kurtzer, an original CentOS co-founder, responded to the announcement by proposing a new community enterprise distribution and naming it Rocky Linux after CentOS co-founder Rocky McGaugh. The project organized through what became the Rocky Enterprise Software Foundation.

Rocky Linux 8.4 reached general availability on June 21, 2021 for x86-64 and AArch64. Its stated goal was compatibility with RHEL and to restore the downstream community-build role. The first release took months of infrastructure, package rebuild, signing, testing and mirror work; it was not produced the night of the announcement.

AlmaLinux arrived independently

CloudLinux announced Project Lenix, later AlmaLinux, along a parallel path. AlmaLinux OS 8.3 stable shipped March 30, 2021, before Rocky 8.4 GA. The AlmaLinux OS Foundation later became its nonprofit governance home.

The two projects were not one fork with two brands. They developed separate build infrastructure, governance, errata/mirrors, funding and later compatibility strategies. Organizations needed to evaluate each rather than assume “old CentOS with a new logo.”

CentOS Linux eventually ended completely

CentOS Linux 8 updates ended as announced on December 31, 2021. CentOS Linux 7 reached end of life June 30, 2024. CentOS Stream continued as the CentOS distribution/development platform, with version-specific lifecycles such as Stream 8 and Stream 9.

An old CentOS Linux host did not automatically become Stream/Rocky/Alma. Repository conversion or reinstall had to account for third-party packages, Secure Boot keys, kernel modules, management agents, databases, configuration and support contracts.

2023 source-delivery changes added another chapter

In June 2023, Red Hat made CentOS Stream the public location for RHEL-related source work and changed public access to exact RHEL SRPMs previously published at git.centos.org. Rocky said it would adapt its build methods; AlmaLinux later emphasized ABI compatibility rather than promising one-to-one bug reproduction.

That later event should not be retroactively described as the cause of Rocky’s 2020 founding. It changed how downstream projects pursued their goals after they already existed.

The operational lesson is lifecycle ownership

Community availability does not eliminate roadmap, governance or supply-chain dependencies. Before choosing an enterprise distribution, document who controls release gates, source/build/signing infrastructure, update EOL, security advisories, migration tools, commercial support, and fallback.

The December 2020 shift mattered because it changed a deployed contract-like expectation without changing every CentOS release at once. Rocky/Alma demonstrated that open licensing enabled new integration communities, while the time required to build them showed that a distribution is far more than recompiling RPMs.

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