CentOS Stream

CentOS was once the most popular free RHEL alternative in the enterprise Linux world. In late 2020, Red Hat announced the shift from traditional CentOS Linux to CentOS Stream, triggering a massive transformation across the entire community. Understanding this history and CentOS Stream’s new positioning is essential for every EL user.

CentOS History

Traditional CentOS (2004-2021)

CentOS (Community Enterprise Operating System) was originally an independent community project that recompiled RHEL’s publicly available source code into a binary-compatible free distribution.

Core concept: Remove Red Hat branding, rebuild RHEL source RPMs (SRPMs), and provide a fully compatible free alternative.

This model made CentOS extremely popular for:

Budget-constrained small and medium businesses
Web hosting and server hosting
Development and testing environments
Educational and research institutions

Red Hat Acquires CentOS Project (2014)

In 2014, Red Hat brought the CentOS project under its umbrella. The CentOS team joined Red Hat, and the project received more resources — but this also set the stage for the later transformation.

During this phase, CentOS continued its original model as a downstream rebuild of RHEL.

The CentOS Stream Pivot (2020-2021)

In December 2020, Red Hat announced:

CentOS Linux 8 would reach EOL by the end of 2021 (originally planned for support until 2029)
CentOS Linux 7 would continue as planned until June 2024
The CentOS project would henceforth focus on CentOS Stream

This decision caused enormous community backlash and directly spawned AlmaLinux and Rocky Linux as RHEL-compatible alternatives.

What is CentOS Stream

CentOS Stream is the continuously delivered upstream for RHEL. Its positioning has fundamentally changed:

Old model: Fedora → RHEL → CentOS (downstream rebuild)
New model: Fedora → CentOS Stream → RHEL (midstream development)

Key Differences from Traditional CentOS

Feature	Traditional CentOS	CentOS Stream
Relationship to RHEL	Downstream (follows)	Upstream (leads)
Update frequency	Follows RHEL minor releases	Continuous rolling updates
Package versions	Identical to RHEL	Slightly ahead of current RHEL minor version
Stability	Equal to RHEL	Slightly less than RHEL GA, but much more than Fedora
Positioning	Free RHEL replacement	Open collaboration platform for RHEL development

CentOS Stream Update Model

CentOS Stream rolls updates within a major version. For CentOS Stream 9:

It contains changes destined for the next RHEL 9.x minor release
Updates are continuous — there are no “9.1” or “9.2” point releases
Every update passes CI testing, but does not go through RHEL’s full QA process

In practice, the gap between CentOS Stream updates and the next RHEL minor release is usually small. For most workloads, CentOS Stream’s stability is sufficient.

Use Cases

Good Fit for CentOS Stream

Development and Testing
- Test changes coming to RHEL ahead of time
- Ensure your applications are compatible with upcoming RHEL releases
Contributing to RHEL
- CentOS Stream is the public channel for submitting bug fixes and improvements to RHEL
- Anyone can participate in RHEL development through CentOS Stream
CI/CD Pipelines
- Use CentOS Stream in CI for building and testing
- Discover potential compatibility issues early
Non-critical Production
- Internal services that do not require strict RHEL compatibility
- Web development and application deployment

Not Ideal For

Production environments requiring 100% RHEL binary compatibility
Environments needing long-term fixed package versions
Running commercial software certified specifically for RHEL

Installation and Usage

Getting CentOS Stream

Download: www.centos.org/centos-stream/

Currently available versions:

CentOS Stream 9: Active development (tracks RHEL 9.x)
CentOS Stream 10: Active development (tracks RHEL 10.x)

Basic Commands

# Check version information
cat /etc/centos-release

# Update the system
dnf update -y

# List available repositories
dnf repolist

# Install EPEL (Extra Packages for Enterprise Linux)
dnf install -y epel-release

Repository Structure

CentOS Stream repositories correspond to RHEL:

Repository	Description
baseos	Core OS packages
appstream	Applications and runtimes
crb	CodeReady Builder equivalent
extras-common	Additional community tools

SIGs (Special Interest Groups)

An important part of the CentOS project is its SIGs, which provide additional packages and infrastructure around specific topics:

SIG	Focus Area
Cloud	Cloud infrastructure (OpenStack, etc.)
Virtualization	Virtualization technologies (KVM, oVirt, etc.)
Storage	Distributed storage (Ceph, GlusterFS, etc.)
NFV	Network Function Virtualization
Automotive	In-vehicle Linux
Hyperscale	Hyperscale infrastructure optimization
Kmods	Kernel modules

SIG-provided packages are distributed through dedicated repositories that can be enabled on demand:

# Example: List available CentOS SIG repositories
dnf repolist --all | grep -i sig

Migrating from Traditional CentOS

If you are still running traditional CentOS Linux, here are your migration paths:

CentOS Linux 7 (EOL)

Use AlmaLinux’s ELevate tool to upgrade to EL 8/9
Fresh install of CentOS Stream 9 or another EL 9 distribution

CentOS Linux 8 (EOL)

CentOS Stream 8 also reached EOL on 2024-05-31, so don’t migrate to it. Recommended paths:

Migrate in place to AlmaLinux 8 or Rocky Linux 8 (still in maintenance support)
Upgrade directly to EL 9 / EL 10

Source Code and Build System

All CentOS Stream source code is publicly available through GitLab:

Source repository: gitlab.com/redhat/centos-stream
Build system: Koji

This is the best way to see what changes are coming to RHEL, and it is the primary source for all RHEL-compatible distributions to obtain source code (since Red Hat restricted SRPM access in 2023).

Summary

CentOS Stream is no longer “free RHEL” — it is “the development frontier of RHEL.” For users who need a free RHEL-compatible distribution, AlmaLinux and Rocky Linux are more direct choices. But CentOS Stream continues to play an important role in development, testing, and contributing to the RHEL ecosystem.

Understanding CentOS Stream’s positioning helps you make the right choice among the many EL distributions available.