Rocky supported version upgrades

OR How to duplicate any Rocky machine.

Introduction¶

Since day one of the Rocky Linux project, some have asked: How do you upgrade from CentOS 7 to Rocky 8, or Rocky 8 to Rocky 9? The answer is always the same: The project does not support in-place upgrades of one major version to another major version. You need to reinstall to move to the next major version. To be clear, this IS the correct answer. This document allows users to move from one major version to the next, using the correct Rocky-supported procedure for a fresh installation. You can use this method to rebuild the same Rocky Linux version. For example, install 9.5 to a fresh 9.5 with all the packages.

Caveats

Even given this procedure, many things can go wrong when going from an older version of one operating system (OS) to a newer version of the same or different OS. Programs become obsolete and replaced by the maintainers with completely different package names, or the names do not match up from one OS to the next. Also, please know about your machine's software repositories and verify they are still functional for the new OS. If going from a much older version to a much newer one, please ensure that your CPU and other machine requirements match the new one. For these and many different reasons, you must remain cautious and note any errors or problems while performing this procedure. Here, the author has used Rocky Linux 8 as the old version and Rocky Linux 9 as the new major version. The formulation of all examples uses these two versions. You can always go ahead and proceed at your own risk.

Steps summary¶

Obtain a list of users from the old installation (userid.txt).
Obtain a list of repositories from the old installation (repolist.txt).
Obtain a list of packages from the old installation (installed.txt).
Backup all data, configuration, utilities, and scripts from the old installation to a non-volatile location along with the .txt files created.
Verify that the hardware you will be installing supports the operating system that you are installing. (CPU, memory, disk space, and so on.)
Perform a fresh install of the operating system you use on the hardware.
Do a dnf upgrade to get any packages that might have been updated since the ISO file's creation.
Create any needed users by examining the userid.txt file.
Install any missing repositories that are not Rocky-related in the repolist.txt file. (See notes for the EPEL and Code Ready Builder (CRB) repositories.)
Install the packages using the procedure for the installed.txt file.

Steps detail¶

Same version upgrades

As discussed earlier, this procedure should work equally well to duplicate a machine installation with the same operating system release, such as 8.10 to 8.10 or 9.5 to 9.5. The difference is that you should not need --skip-broken when installing the packages from the installed.txt file. If you get package errors when installing a version, you are probably missing a repository. Stop the procedure and re-examine the repolist.txt file. The examples here use 8.10 as the old installation and 9.5 as the new one.

Version 10 is unknown

Because of the vast changes between 9.5 and the upcoming version 10, this procedure might not work to move between 9.5 and 10. The exploration of this will occur once there is a release of 10 to test.

Example old machine¶

The old machine used here is Rocky Linux 8. The installation includes several Extra Packages for Enterprise Linux (EPEL) repository packages.

Code Ready Builder

The Code Ready Builder (CRB) repository in Rocky Linux 9 replaces functionality in the deprecated PowerTools repository that existed in version 8. If moving from an 8 version to 9 where you have the EPEL, you will need to enable the CRB on your new machine with the following:

sudo dnf config-manager --enable crb

Obtain a list of users¶

You will need to manually create any users on the new machine, so you need to know what user accounts you will need to create. User accounts generally start at user id 1000 and increment upwards.

sudo getent passwd > userid.txt

Obtain a list of repositories¶

You need a list of the repositories that exist on the old machine:

sudo ls -al /etc/yum.repos.d/ > repolist.txt

Obtain a list of packages¶

Generate the package list with the following:

sudo dnf list installed | awk 'NR>1 {print $1}' | sort -u > installed.txt

Here, the NR>1 eliminates record one from the column, which has the "Installed" that came from the dnf list installed command. It is not a package, so you do not need it. The {print $1} means only use column one. You do not need the package version or the repository it came from in the listing.

You will not need to install any kernel-related packages. It does not hurt to install them again if you leave this step out. You can remove the kernel lines with:

sudo sed -i '/kernel/d' installed.txt

Backup any data¶

This can encompass many things. Make sure you know the purpose of the machine you are replacing and all of its program components (database, mail server, DNS, and more). If you have any doubts, just back it up.

Copy files¶

Copy the text files you created to a non-volatile location and all the backup data.

Example new machine¶

Your fresh installation of Rocky Linux 9 is complete. You need to get any package updates since the creation of the ISO image:

sudo dnf upgrade

You are ready to start copying your text files and backups from where you stored them in the earlier procedure.

Create the users¶

Examine the userid.txt file and create the users you need on the new machine.

Install the repositories¶

Examine the repolist.txt file and manually install the repositories you need. You can ignore the Rocky-related repositories. Remember that we have packages from the EPEL, so you will need the CRB repository rather than PowerTools:

sudo dnf config-manager --enable crb

Install the EPEL:

sudo dnf install epel-release

Install any other repositories from the repolist.txt file that are not Rocky or EPEL-based.

Install the packages¶

Once installation of the repositories completes, try to install your packages from installed.txt:

sudo dnf -y install $(cat installed.txt)

Some packages will not exist between Rocky Linux 8 and Rocky Linux 9, regardless of the repositories you have enabled. Running this command gives you an idea of what those packages are.

Here is what did not install on the author's test machine (reorganized as a column rather than a long string):

Error: Unable to find a match: 
OpenEXR-libs.x86_64 
bind-export-libs.x86_64 
dhcp-libs.x86_64 
fontpackages-filesystem.noarch 
hardlink.x86_64 
ilmbase.x86_64 
libXxf86misc.x86_64 
libcroco.x86_64 
libmcpp.x86_64 
libreport-filesystem.x86_64 
mcpp.x86_64 
network-scripts.x86_64 
platform-python.x86_64 
platform-python-pip.noarch 
platform-python-setuptools.noarch 
xorg-x11-font-utils.x86_64

Note

If you need the functionality of these missing packages on your fresh install, save them in a file for use later. You can see the availability status of missing packages by using this command:

sudo dnf whatprovides [package_name]

Rerun the command, but this time with the --skip-broken appended to it:

sudo dnf -y install $(cat installed.txt) --skip-broken

Because you just made many changes, you should reboot before continuing.

Restore your backups¶

Once you have all the packages installed, restore your backups, modified configuration files, scripts, and other utilities you backed up before moving to your new machine.

Conclusion¶

There is no magic routine (supported by Rocky Linux) to move from one major version to another. Rocky Linux developers support only a fresh install. The routine provided here allows you to move from one major version to another while following the Rocky team's best practices.

This procedure assumes a simple installation. However, if your installation is complex, you might need to take more steps. You can use this procedure as a guide.

Disclaimer¶

While the basic document is the author's, two individuals in the [Forum] (https://forums.rockylinux.org/t/boot-too-small-rebuild/17415) suggested a cleaner way to generate the installed.txt and eliminated the kernel packages. Thanks to all who provided input on that procedure.

Author: Steven Spencer

Contributors: Ganna Zhyrnova