As a newbie my first question, for which I did not find that it has previous been asked, is which server distro(s) has the best automated upgrade utilities for installing new releases without having to do a complete reinstall from scratch.

For context, I used to be a Unix reseller many years ago which had great upgrade utilities, but I never switched to Linux when it became popular because it had none, and required too much time to install upgrades and customers did not understand why they had to pay for so much more time. I have developed some vertical software that runs on Windows and Linux and while most sales probably will be for Windows, I hope to push Linux as much as possible. To do so, I need to find a great server distro that also makes it as painless as possible for users to upgrade. All the distros may have these capabilities now, but I am not familiar with enough different distros to know which ones do a good job in this regard.

For clarity, what I mean by "automated upgrade utilities", using Unix as an example, are programs that will save-off all the admin configurable files - user login and profiles, printer setup or config files, password files, group files, network config, startup files, crontab & scripts, and others - install the OS upgrade without touching the /usr/bin or /var/bin directories, then coping back all the saved-off files and reboot the server. I am probably forgetting some steps, but that is the gist of it. That process usually took about 1-2 hrs to install, config new features, and test to be sure the upgrade worked and didn't mess up something.

Regards
planodan

What you've described doesn't sound very automated.

Assuming you've backed up competently, in Debian, online upgrade consists of as little as the following:

1. edit /etc/apt/sources.list to change the distro's release name from old to new on each line item
2. clear the packages cache of old packages (technically unnecessary; apt clean)
3. update packages database (apt update)
4. upgrade (apt upgrade; apt dist-upgrade)
5. reboot

In openSUSE, updating the packages database will be performed automatically by the upgrade command when not done as a separate step. IME, both Debian and openSUSE distribution upgrade processes are seriously competent, having been refined over many years of evolution and experience. Also IME, though not really intended as server distros, Fedora's and Mageia's upgrade processes are also refined, simple and competent. Given CentOS is a Fedora derivative, it should be similarly competent. I don't often install any of these distros fresh except on a new PC or boot disk. Upgrading works too well to hassle with re-customizing after a fresh installation.

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Thanks, good info that is very helpful!

You're welcome!

Centos and RHEL are both very good and easily updated server systems that have benefited from years of refinement similar to that noted above. Ubuntu also has a very good system.
Most systems can today be upgraded from one release to the next with very little need for reconfiguration.

The simple process of backing up the critical config files as you describe in case of errors, then an online upgrade followed by a reboot is usually all that is required; regardless of the linux distro in use. Seldom does it require more than an hour to do a full system upgrade.

Sorry, but no, there's currently no officially supported way of upgrading CentOS to the next major release other than a fresh install from scratch. Upgrade tools that work for RHEL, don't work for CentOS. They even took down description of the upgrade process from their Wiki. Also see this thread on forums.centos.org

That change is probably due to the (fairly) recent switch where they discontinued the Centos Linux distro and now are only providing the Centos Stream version. It is available here. Stream is a rolling release. A little behind Fedora since fedora is the test bed, but still a rolling release and ahead of RHEL.

In fact, Centos 8 reaches end of support this year.

I am looking forward to finishing the build on my new system and installing Centos Stream on it.

IIRC, dropping the upgrade process preceded the latest developments by quite a while. The wiki page I linked to originally concerned upgrades from CentOS 6 to CentOS 7. That upgrade path was dropped long before CentOS 8 appeared: the link to the tool was removed in November 2017. And the tool was neglected for quite some time before that.

There never was an official upgrade path from CentOS 7 to CentOS 8. The CentOS project just didn't have the manpower required to maintain the upgrade tool and test the upgrade process.

One thought regarding automatic upgrades:

The very few sysadmins that I have known personally want no part of automatic upgrades. They want to be able to schedule any upgrade when it's convenient to their organizations and to be present and in control during any upgrade process, however minor, in case something goes awry.

I doubt that you will find a reliable server distro, or a reliable distro to use as a server, with that feature. (Pretty much any Linux distro can be used as a server--the primary feature that distinguishes "server" distros from desktop distros is that they come without a GUI installed, as most servers sit in racks in datacenters and are administered remotely via the command line or with tools such as WHM and phpMyAdmin, and with all server software preinstalled.)

I don't think anyone is talking about automatic upgrades - planodan asked about "automated upgrade utilities" which they then clarified as (afaict) being an backup/restore tool.

The cPanel/WHM software you mention is one such option - with it the admin can backup/export all user-related files and configuration and then restore/import those to a newly prepared server, making upgrades far less painful than manually transferring everything.

However, I don't recommend cPanel/WHM - it uses non-standard locations which can make it confusing to administer from the command line, is proprietary subscription software, and recently upset a lot of hosting providers by switching from per-instance to a per-account fee.

I assume other control panel / server manangement software has similar functionality which may or not be better or worse than WHM.

That is correct, I'm not asking about "automatic upgrades" that install themselves on the server with or without administrator or users permission, as can occur in a Windows environment. I am asking about utilities that are run from the command line that automate what would otherwise be a manual process of saving admin type configuration or customized files, loading the new OS features (files) and not disturbing the users' application, database, and data files, i.e. those typically kept in /usr/bin or /var/bin. That to me is the meaning of an upgrade to an existing installation. If one has to do a fresh install of a new version, that scenario, to me, is not an "upgrade" but an "install of a new release", the latter being a different animal altogether.

I would expect each distro to have its own version of these utilities, if they provide them at all, because of the differences in what they add, include and customize that makes their distro unique. Therefore, I am not expecting to find a universal utility that performs upgrades.

I understand most Linux server packages do not include a GUI interface and why. Personally, if I was creating a distro, I would make a GUI optional for those scenarios where the distro is installed on a server, whether rack mounted or not, in environments where the admins are not power Linux users or trained personnel, like small to medium sized businesses. With a GUI, those user types can be easily trained to do light admin functions like add a new user, handle simple printer issues, load a self-installing application software package, and other light functions, as they would do with a Windows server. Adding automated upgrade utilities would not be something the type of person I am describing above would typically perform. If the person qualifies as a well trained admin, then yes they could install an upgrade. If not, a company's systems consultant or provider could do so without it being a major time consuming engagement. A utility such as this is a professional refinement that is a differentiator and makes a distro a complete package for business use as opposed to a pure internet play. This is not part of the question, but perhaps it adds a little more context to my question. I understand business is not the major market for Linux, but perhaps without these types of refinements is one reason it isn't.

Thanks for the good answers and info, they are very helpful.

Actually RHEL is aimed at businesses as a very reliable enterprise level server. I am not fully aware of all the enterprise server distros available, but there are some others as well.

I suppose that most admins of companies using RHEL and the like may have utilities for what you describe as an update. Now that you have clarified it as upgrades to the services rather than the operating system I can see it applies for situations such as upgrading a database server or web server (among others) to a newer version of the app.

The specific needs there are unique to each service being upgraded so I am not sure any standard tools are available to fully automate that type upgrade. Vendors of those apps would likely have something to recommend for version upgrades.

Sometimes the configuration is tweaked according to the size of the app, the hardware available, etc. If the install is fully standard and nothing has been altered from the designed installation then an automated script for doing the upgrade seems pretty standard. If the configuration is unique to the way the organization installed it (non-standard) then a little bit of unique tweaks in upgrade procedures are required for that reason.

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The easiest trustable way that I know is that in Rocky Linux or maybe any CentOS based distro you can manage your server with Cockpit via browser, in there you can go to "Software Updates" menu and there schedule one day of the week for security or all updates and it will even reboot for you after it's done if needed.

In Ubuntu you have unattended upgrades package that you can install and tweak to do this in the way you want too.

If you want to save it all before updating, maybe boot Clonezilla and image your server or if those were virtual machines, just power off and copy VM files although this would probably take a lot of space in another disk.

I want to say that I've used Webmin before for managing and you can use to update and see the output too. If I recall correctly this has some export and import features that can help you in migrations.

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Historically RHEL (& therefore derivatives) have always had good in-place upgrades for minor version upgrades eg 6.x -> 6.x+1, but have always reqd a fresh install for major version upgrades eg 6 -> 7.
Major version changes allow them to do breaking changes.

As far as I know, this is still the case, so eg RHEL 8 -> RHEL 9 will be the same.
I would be very(!) surprised if this did not apply to Centos stream 8 -> 9 as well, even if it is slightly upstream. Either something is a breaking change (serious architecture change) or it isn't.

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All the replies are great info and very helpful!

The only two distros I have used in the past are RH and Ubuntu. I have used them only to test my software, and I also setup RH as a db server in a test configuration. That is why my exposure to other distros in so limited, and my use of Ubuntu & RH is very light and command line only. So I very much appreciate the help and input. I was not aware that either of the two distros I have used, had the upgrade utilities mentioned. Hopefully, Rocky will be even a new and improved Centos 2, and I am looking forward to trying it.

Regards to all!
Danny