How to migrate from CentOS 8 to CentOS stream

How to migrate from CentOS 8 to CentOS stream

In this Article I'll show you How to migrate from CentOS 8 to CentOS stream. CentOS 8 is ending soon. Red Hat is making the shift from CentOS 8 to CentOS Stream. CentOS stream places itself between Fedora Linux and RHEL. It is not 100% RHEL clone but ahead of RHEL development. Think of it as a midstream distro. Of course, if you need 100% RHEL compatibility, then you need Rocky Linux or AlmaLinux. However, the CentOS stream is more than sufficient for me as I only need Apache, Perl, and Python for my use case. This page explains how to migrate the existing installation of CentOS 8 stable to CentOS Stream without reinstalling a new operating system.

How to migrate from CentOS 8 to CentOS stream

CentOS Stream is an open-source operating system and one of the replacement candidates for CentOS 8. However, I decided to stick with CentOS Stream because I didn’t have time or energy to install a new replacement such as Rocky Linux or AlmaLinux. Then restore data. It is too much work for my side project. Eventually, I will convert my legacy app to Docker format, but for now, I am going to upgrade my VM and save some time. So without further ado, let us see how to migrate from CentOS 8 to CentOS Stream using the ssh command.

Step 1 – Backup

Like every seasoned developer and sysadmin, I backed up all my project files, MySQL database and config files. So if something goes wrong, I should be able to go back quickly. That is all. Hence, keep verified backups. I have following software installed:

  • ELEP repo enabled for CentOS 8
  • SELinux and FirewallD on CentOS 8 enabled
  • Python 3.6.8.
  • python3-mod_wsgi.
  • Perl 5.26.3.
  • mod_perl 2.0.11-4.
  • Apache (httpd) 2.4.37 with mod_ssl, mod_security, mod_session, mod_speedycgi and other modules.

Step 2 – Installing all updates on CentOS 8

Login using the ssh command:
ssh [email protected]
Next, simply run the dnf command:
sudo dnf update
Then reboot the Linux box using the shutdown command or reboot command:
sudo shutdown -r now
Let us verify CentOS Linux 8 version using the cat command/more command or less command:
more /etc/centos-release

My fully patched CentOS 8 stable ready for migration to CentOS Stream

Step 3 – Installing CentOS Stream package

Let us install the CentOS-Stream release file by typing the following dnf command:
sudo dnf in centos-release-stream

Installing CentOS-Stream release files

Step 4 – Migrating From CentOS 8 to CentOS Stream

Now we have the required package is in place. In other words, the dnf is ready to provide a simple way for us to start migrating from CentOS 8 to CentOS Stream. But, first, we must swap repos. The following command will remove CentOS 8 repo and replace it with the CentOS Stream repo. We will get all updates and libs/apps from CentOS Stream. Execute the following command:
sudo dnf swap centos-linux-repos centos-stream-repos

Last metadata expiration check: 0:07:46 ago on Friday 03 December 2021 05:14:03 PM UTC.
Dependencies resolved.
 Package                      Architecture  Version          Repository            Size
 centos-stream-release        noarch        8.6-1.el8        Stream-BaseOS         22 k
     replacing  centos-linux-release.noarch 8.5-1.2111.el8
     replacing  centos-release-stream.x86_64 8.1-1.1911.0.7.el8
 centos-stream-repos          noarch        8-3.el8          extras                19 k
 centos-linux-repos           noarch        8-3.el8          @baseos               26 k
Transaction Summary
Install  2 Packages
Remove   1 Package
Total download size: 42 k
Is this ok [y/N]: y
Downloading Packages:
(1/2): centos-stream-repos-8-3.el8.noarch.rpm           588 kB/s |  19 kB     00:00    
(2/2): centos-stream-release-8.6-1.el8.noarch.rpm        61 kB/s |  22 kB     00:00    
Total                                                    91 kB/s |  42 kB     00:00     
Running transaction check
Transaction check succeeded.
Running transaction test
Transaction test succeeded.
Running transaction
  Preparing        :                                                                1/1 
  Running scriptlet: centos-stream-release-8.6-1.el8.noarch                         1/1 
  Installing       : centos-stream-release-8.6-1.el8.noarch                         1/5 
  Installing       : centos-stream-repos-8-3.el8.noarch                             2/5 
  Obsoleting       : centos-release-stream-8.1-1.1911.0.7.el8.x86_64                3/5 
  Obsoleting       : centos-linux-release-8.5-1.2111.el8.noarch                     4/5 
  Erasing          : centos-linux-repos-8-3.el8.noarch                              5/5 
warning: /etc/yum.repos.d/CentOS-Linux-PowerTools.repo saved as /etc/yum.repos.d/CentOS-Linux-PowerTools.repo.rpmsave
warning: /etc/yum.repos.d/CentOS-Linux-Plus.repo saved as /etc/yum.repos.d/CentOS-Linux-Plus.repo.rpmsave
warning: /etc/yum.repos.d/CentOS-Linux-HighAvailability.repo saved as /etc/yum.repos.d/CentOS-Linux-HighAvailability.repo.rpmsave
warning: /etc/yum.repos.d/CentOS-Linux-FastTrack.repo saved as /etc/yum.repos.d/CentOS-Linux-FastTrack.repo.rpmsave
warning: /etc/yum.repos.d/CentOS-Linux-Extras.repo saved as /etc/yum.repos.d/CentOS-Linux-Extras.repo.rpmsave
warning: /etc/yum.repos.d/CentOS-Linux-Devel.repo saved as /etc/yum.repos.d/CentOS-Linux-Devel.repo.rpmsave
warning: /etc/yum.repos.d/CentOS-Linux-ContinuousRelease.repo saved as /etc/yum.repos.d/CentOS-Linux-ContinuousRelease.repo.rpmsave
warning: /etc/yum.repos.d/CentOS-Linux-BaseOS.repo saved as /etc/yum.repos.d/CentOS-Linux-BaseOS.repo.rpmsave
warning: /etc/yum.repos.d/CentOS-Linux-AppStream.repo saved as /etc/yum.repos.d/CentOS-Linux-AppStream.repo.rpmsave
  Running scriptlet: centos-linux-repos-8-3.el8.noarch                              5/5 
  Verifying        : centos-stream-repos-8-3.el8.noarch                             1/5 
  Verifying        : centos-stream-release-8.6-1.el8.noarch                         2/5 
  Verifying        : centos-linux-release-8.5-1.2111.el8.noarch                     3/5 
  Verifying        : centos-release-stream-8.1-1.1911.0.7.el8.x86_64                4/5 
  Verifying        : centos-linux-repos-8-3.el8.noarch                              5/5 
  centos-stream-release-8.6-1.el8.noarch       centos-stream-repos-8-3.el8.noarch      

Finally migrate CentOS 8 installation to CentOS stream

First list repos, run:
sudo dnf repolist

Upgrading CentOS 8 to CentOS Stream

We are now close to our target. Next, we need to get packages for CentOS Stream ABI/API. This will upgrade or downgrade packages to match the new ABI/API and break 100% RHEL compatibility due to ABI/API change. I am OK with that. So let us do it:
sudo dnf distro-sync

Last metadata expiration check: 0:00:19 ago on Friday 03 December 2021 05:28:32 PM UTC.
Dependencies resolved.
 Package                     Arch   Version                             Repo       Size
 NetworkManager              x86_64 1:1.36.0-0.1.el8                    baseos    2.3 M
 NetworkManager-libnm        x86_64 1:1.36.0-0.1.el8                    baseos    1.8 M
 NetworkManager-team         x86_64 1:1.36.0-0.1.el8                    baseos    149 k
 NetworkManager-tui          x86_64 1:1.36.0-0.1.el8                    baseos    341 k
 bash                        x86_64 4.4.20-3.el8                        baseos    1.5 M
 c-ares                      x86_64 1.13.0-6.el8                        baseos     93 k
 ca-certificates             noarch 2021.2.50-82.el8                    baseos    390 k
 cloud-init                  noarch 21.1-9.el8                          appstream 1.0 M
 cpio                        x86_64 2.12-11.el8                         baseos    266 k
 cronie                      x86_64 1.5.2-6.el8                         baseos    118 k
 cronie-anacron              x86_64 1.5.2-6.el8                         baseos     42 k
 crypto-policies             noarch 20211116-1.gitae470d6.el8           baseos     64 k
 crypto-policies-scripts     noarch 20211116-1.gitae470d6.el8           baseos     83 k
 device-mapper               x86_64 8:1.02.181-1.el8                    baseos    377 k
 device-mapper-libs          x86_64 8:1.02.181-1.el8                    baseos    409 k
 dnf                         noarch 4.7.0-5.el8                         baseos    543 k
 dnf-automatic               noarch 4.7.0-5.el8                         baseo
 vim-enhanced                x86_64 2:8.0.1763-16.el8_5.2               appstream 1.4 M
 vim-filesystem              noarch 2:8.0.1763-16.el8_5.2               appstream  49 k
 vim-minimal                 x86_64 2:8.0.1763-16.el8_5.2               baseos    573 k
 yum                         noarch 4.7.0-5.el8                         baseos    206 k
Installing dependencies:
 glibc-gconv-extra           x86_64 2.28-170.el8                        baseos    1.4 M
Installing weak dependencies:
 sqlite                      x86_64 3.26.0-15.el8                       baseos    668 k
 unzip                       x86_64 6.0-45.el8                          baseos    195 k
Transaction Summary
Install     2 Packages
Upgrade    86 Packages
Downgrade   1 Package
Total download size: 95 M
Downloading Packages:
(1/89): unzip-6.0-45.el8.x86_64.rpm                     571 kB/s | 195 kB     00:00    
(2/89): sqlite-3.26.0-15.el8.x86_64.rpm                 1.4 MB/s | 668 kB     00:00    
  glibc-gconv-extra-2.28-170.el8.x86_64           sqlite-3.26.0-15.el8.x86_64          

Step 5 – Reboot the system

sudo systemctl reboot

Step 6 – Verification

See CentOS stream version for verification:
cat /etc/centos-release

Make sure there are no errors. Let us see or view errors log on Linux:
sudo tail -f /var/log/messages
sudo grep -i -E 'err|wan|cri' /var/log/messages
sudo grep -i -E 'err|wan|cri' /var/log/nginx/error.log

List open ports on Linux and make sure services such as httpd, mysqld and stuff is running using the systemctl command or netstat command/ss command:
sudo ss -tulpn
systemctl status httpd
systemctl status mysqld

Summing up

I am pleasantly surprised by how smoothly the process went. This saved me time. I am also aware that one can take a similar approach to switch to AlmaLinux or RocyLinux, or Oracle Linux by swapping repos. For now, my side project working smoothly on AWS EC2 VM. But, one can use self-hosted or other cloud service providers too. I also deployed a local Rocky Linux VM on my Laptop, where I will containerize my app, so I no longer have to depend on the host OS. That is why I didn’t waste much time with a completely new OS. Do check out the CentOS Stream website for documentation.