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What failed with Fedora that RHEL couldn't use that as upstream? Wasn't that supposed to be where Centos Stream is going?

ghaff 6y ago
RHEL does use Fedora as an upstream but only to rebase major versions. And RHEL may also make different decisions about various components. For example, btfs is now the default file system for Fedora but not RHEL. CentOS Stream is much closer to RHEL. It's basically the ongoing post-CI builds.
- m4rtink 6y ago
  Yep, Fedora is where all new and improved Linux software gets integrated, often being the first Linux distribution where it lands. Many projects (GCC, Gnome any likely others) synchronize their release timelines due to this. The end result is a a rather nice and lately also quite stable modern Linux distro one can use on a PC and other platforms (there is a IoT edition now, container image, Fedora based CoreOS and others). Then every ~3 years Red Hat takes a snapshot of a released Fedora version and basically "productizes" it into a new RHEL release. This means many things, such as cutting package dependencies quite a bit to only ship what the customers expect and what can be expected to be maintainable for the 10 years of support RHEL has. There could be also some "RHELification" when a package is expected to have different default behavior than in Fedora, but most of that is done by spec file macros these days, so RHEL-only RHELification patches are thankfully rare. Then after a given RHEL version GA, there are minor releases about twice a year. for RHEL 8 for example you have 8.0, 8.1, 8.2, etc. And this is where CentOS stream actually comes in - it's effectively the continuous RHEL release that makes the point releases possible. Packages are updated for the the next point release and land in CentOS stream, then when all is ready for the next point release of RHEL, it is cut from the properly QAed CentOS stream state, which then starts tracking the next minor release. This is actually quite an improvement for the usecase of software building on top of RHEL, as instead of getting only a big bunch of surprise twice a year, they can now track what will be in the next release and either adjust or report issues soon enough for them to be fixed before the next point release. I'm thinking this rather important fact what CentOS stream actually is got kinda "lost in translation" as you can see various things stated as facts about it that are wrong: "CentOS stream is between Fedora and RHEL" - well, no, it's the source of the next RHEL minor release & nothing goes directly from Fedora to a point release. "CentOS stream is less stable than RHEL/CentOS" - well, it's the next RHEL, nothing that does not pass the high RHEL standards is expected to land in it for obvious reasons.

ghaff 6y ago

RHEL does use Fedora as an upstream but only to rebase major versions. And RHEL may also make different decisions about various components. For example, btfs is now the default file system for Fedora but not RHEL. CentOS Stream is much closer to RHEL. It's basically the ongoing post-CI builds.

m4rtink 6y ago
Yep, Fedora is where all new and improved Linux software gets integrated, often being the first Linux distribution where it lands. Many projects (GCC, Gnome any likely others) synchronize their release timelines due to this. The end result is a a rather nice and lately also quite stable modern Linux distro one can use on a PC and other platforms (there is a IoT edition now, container image, Fedora based CoreOS and others). Then every ~3 years Red Hat takes a snapshot of a released Fedora version and basically "productizes" it into a new RHEL release. This means many things, such as cutting package dependencies quite a bit to only ship what the customers expect and what can be expected to be maintainable for the 10 years of support RHEL has. There could be also some "RHELification" when a package is expected to have different default behavior than in Fedora, but most of that is done by spec file macros these days, so RHEL-only RHELification patches are thankfully rare. Then after a given RHEL version GA, there are minor releases about twice a year. for RHEL 8 for example you have 8.0, 8.1, 8.2, etc. And this is where CentOS stream actually comes in - it's effectively the continuous RHEL release that makes the point releases possible. Packages are updated for the the next point release and land in CentOS stream, then when all is ready for the next point release of RHEL, it is cut from the properly QAed CentOS stream state, which then starts tracking the next minor release. This is actually quite an improvement for the usecase of software building on top of RHEL, as instead of getting only a big bunch of surprise twice a year, they can now track what will be in the next release and either adjust or report issues soon enough for them to be fixed before the next point release. I'm thinking this rather important fact what CentOS stream actually is got kinda "lost in translation" as you can see various things stated as facts about it that are wrong: "CentOS stream is between Fedora and RHEL" - well, no, it's the source of the next RHEL minor release & nothing goes directly from Fedora to a point release. "CentOS stream is less stable than RHEL/CentOS" - well, it's the next RHEL, nothing that does not pass the high RHEL standards is expected to land in it for obvious reasons.