As you should recall, CentOS 8 came out on Tuesday, September 24, 2019. On that date they also announced CentOS 8 Stream. I've had the opportunity to play with it some, do a few installs, see what's there as well as checking the state of the two most popular third-party repos (EPEL and rpmfusion).
... a much newer kernel to start with. EL7 has 3.10.x and EL8 has 4.18.x. As you may recall, EL8 is loosely based on Fedora 28. One good thing about having a much newer kernel is that things like username spaces work better and that trickles down into things like podman and rootless / unprivledged containers actually working... whereas they were basically broken in EL7. A much newer kernel also brings its share of hardware enablement and a bit of legacy hardware being dropped. Have an older server with a RAID card? Better check those release notes to ensure it is still supported. If not, there's a good chance that the third-party ELrepo repository has you covered.
One oddity at time-of-writing is that cockpit in EL7.7 is newer (version 195) that what is in EL8 (version 185). I'm guessing cockpit will receive in an update in EL8 in the not-too-distant future putting it in parity or surpassing what is in EL7.
While yum is still there, it's really a symlink to dnf. I'm guessing most all Fedora users would agree that dnf is more of a pleasure to use than yum. Speaking of package managers, EL8 now has streams which obviously came from Fedora where it they are called modules from their Modularity project. Unfamiliar with modularity? It is a way of providing multiple versions of packages although you can only have one version installed at a time. Need something older or need something newer? You decide. It allows EL8 to still provide the slower changing personality we've come to expect in Enterprise Linux while at the same time accommodating those who might want / need something newer.
I could go on and on enumerating package updates but I'll leave it to those fine release notes. One last thing to mention is that KDE Plasma is no longer available from the stock CentOS repositories.
Yes. At least this early in the release. There are only two install .iso files to pick from... one being a half-GB netinstall and the other being a 6.6GB DVD image. There currently isn't a min CD image. There currently isn't any LiveDesktop media (they only offer GNOME now) . I believe some of their cloud KVM, vagrant, Amazon AMI, and container images are still in the works as are all of the updates. While that's quite a bit of stuff, they are working on it and I expect we'll see those things start to appear shortly. You have to remember that they basically have two full blown flavors now, regular and Stream.
There isn't a livecd-tools package in the CentOS Extras repository anymore and that kind of bums me out because I really preferred to use livecd-creator (historically provided by the livecd-tools package) over livemedia-creator (provided by the lorax package). I've been trying my best to build a few personal EL8 remixes with livemedia-creator and I have yet to get it to work. One has to wonder if that is part of the reason CentOS doesn't have any LiveMedia available yet.
What exactly is CentOS 8 Stream?
The gist of Stream is that it is a rolling release. Wait, weren't minor version upgrades painless and basically rolling in nature... meaning no clean install required, just use your package manager to upgrade? Yes. Is CentOS 8 Stream different? Yes. Basically rather than waiting for a new .x+1 point release to come out where you have a large number of packages to update all at once, Stream will offer updates to things more frequently, over time during the normal lifecycle of your release. I'm not sure if Stream will have point releases or not.
Will there be a CentOS 9 Stream release before RHEL 9 comes out? Will CentOS 8 Stream be easily upgradable to CentOS 9 Stream in true rolling release fashion? Maybe... probably... but the 8-Ball says the future is currently unclear. Since we are so early in the lifecycle, there currently isn't much different between CentOS 8 and CentOS 8 Stream. Obviously there are a number of use cases for Stream and I'm sure the plan for it will be modified over time as needs dictate. I do have to wonder why much of their goals couldn't have be accomplished with package streams. As previously mentioned, with package streams, newer stuff can be easily and non-disruptively offered. I'm guessing they have much broader plans for Stream that haven't been articulated yet... or maybe Stream is going to be more disruptive than they want to be with streams. Oh, and why did they have to use the same word with 1 letter difference?
I am fairly confident that a significant number of EL users use Fedora's Extra Packages for Enterprise Linux (EPEL) and while EPEL8 is available, compared to the vast numbers of packages in EPEL7, EPEL8 still has a ways to go. You should recall that KDE Plasma isn't in CentOS proper anymore, but rest assured that it is in EPEL8 Playground. I believe one thing currently slowing down the appearance of a lot of stuff is the fact that the EPEL automated build system is still being worked on so that it may produce package streams as some EPEL packagers have mentioned that they would prefer to release their stuff via package streams. We'll have to wait and see how that pans out. I'm currently waiting on XFCE and MATE to appear in EPEL8 / EPEL8 Playground. It should also be noted that RPM Fusion has come out with a repository for EL8 where you can find most of the same stuff they offer Fedora users.
There is just so much to be excited about in CentOS 8 and the addition of CentOS 8 Stream will surely offer a lot of possibilities we haven't even thought of yet. One additional thing worth noting is that the Red Hat documentation for RHEL 8 (which CentOS mostly points users to rather than trying to also produce rebranded documentation) has undergone massive changes. Rather than offering the various guides we have grown accustomed to in the past (like the System Administrators Guide, the Network Guide, the Security Guide, etc), the RHEL 8 documentation is task oriented rather than reference oriented. For example, they have a Configuring basic system settings guide and a Deploying different types of servers guide. I'm guessing that there is probably quite a bit over of overlap in the material between the two styles of documentation but the newer one will take a little getting used to. Those who are completely new to the documentation may prefer the new style.
In any event, I really look forward to using CentOS 8 more and putting it through its paces, seeing how Stream evolves, and enjoying all of the new features a new major release offers. Thanks for all of the hard work Red Hat and CentOS!