How CentOS Became CentOS Stream, and Why Rocky Linux Exists Because of It
Red Hat's December 2020 announcement that CentOS Linux would be replaced by CentOS Stream, cutting CentOS 8's support window short and triggering the creation of Rocky Linux in response.
On December 8, 2020, Red Hat announced that CentOS Linux would no longer exist in its original form: rather than continuing as a downstream rebuild of Red Hat Enterprise Linux (RHEL), the project would shift entirely to CentOS Stream, an upstream, rolling-preview branch positioned ahead of RHEL rather than behind it. The change reshaped a significant piece of the enterprise Linux ecosystem almost overnight.
What CentOS actually was, before the change
For most of its history, CentOS Linux served a specific, well-understood purpose: it took RHEL’s source packages (which Red Hat is obligated to publish under the terms of the GPL and other open-source licenses it depends on) and rebuilt them into a free, binary-compatible distribution — the same enterprise-grade software RHEL shipped, without RHEL’s subscription cost. This made CentOS an extremely common choice for production servers, particularly at organizations that wanted RHEL’s stability and long support windows without paying for a support contract they weren’t going to use anyway.
What changed, and why it mattered so much
CentOS Stream inverted CentOS’s position relative to RHEL entirely. Instead of trailing RHEL as a rebuild of already-released, stable packages, CentOS Stream sits upstream of RHEL — a preview of what’s coming in the next RHEL point release, receiving updates before RHEL does rather than after. This is a fundamentally different product serving a different purpose: useful for developers and partners who want early visibility into upcoming RHEL changes, but not a drop-in substitute for the stable, already-released rebuild that CentOS Linux users had relied on.
Compounding the disruption, Red Hat simultaneously cut CentOS 8’s originally planned support window dramatically short — from an expected ten years down to just two, with support ending December 31, 2021, only a fraction of the way through what CentOS 8 users had planned around when they deployed it.
The community’s reaction
The response was swift and overwhelmingly negative, particularly from organizations that had specifically chosen CentOS 8 for long-term production deployments on the understanding it would receive a full decade of updates like its predecessors. The shortened support window meant many CentOS 8 deployments faced an unplanned, accelerated migration timeline they hadn’t budgeted or scheduled for.
Rocky Linux: a direct response
Gregory Kurtzer, one of CentOS’s original creators (who had left the project years earlier), responded by founding Rocky Linux — explicitly positioned as “bug-for-bug compatible” with RHEL, filling exactly the role CentOS Linux had vacated: a free, downstream rebuild of RHEL’s released packages, for exactly the users left without a direct replacement by the shift to CentOS Stream. AlmaLinux, backed by CloudLinux, emerged around the same time pursuing the same goal, giving the ecosystem two independent RHEL-rebuild options where previously there had been one.
The lasting shape of the ecosystem
Years on, the practical result is a more fragmented but arguably more resilient enterprise Linux landscape: CentOS Stream occupies a genuinely useful but different niche as a RHEL preview branch, while Rocky Linux and AlmaLinux absorbed the “free RHEL rebuild” role CentOS Linux used to fill on their own. The episode is frequently cited as a cautionary example of the risk in depending on a single vendor-controlled distribution’s roadmap decisions for production infrastructure planning, regardless of how established that distribution had previously seemed.
Sources: