How to migrate CentOS 8 to CentOS 8 Stream

CentOS 8 went EOL at the end of December 2021. There was no automatic migration to CentOS Stream 8 (which will receive updates till end of May 2024). The following describes how to migrate an existing CentOS 8 installation to CentOS 8 Stream:¹⁾

1. As the content of the CentOS 8 repositories has been moved to vault.centos.org a few days ago, any dnf package operation probably results in “Error: Failed to download metadata for repo 'appstream': Cannot prepare internal mirrorlist: No URLs in mirrorlist”. If so, swap to the Stream repos first:

   sudo dnf --disablerepo '*' --enablerepo=extras swap centos-linux-repos centos-stream-repos

2. Do the migration:

   sudo dnf install centos-release-stream
   sudo dnf swap centos-{linux,stream}-repos
   sudo dnf distro-sync
   cat /etc/centos-release

That's it. On a typical minimal installation, this will replace round about 600 packages.

Additionally, it might make sense to replace third party repositories with a module (→ dnf module list, dnf module info <modulename>). The following example replaces remi-php74 with Stream's php:7.4 module:

• Identify the packages installed from the repository to replace:

  dnf list installed | grep @remi-php74

  Remove these packages bit by bit with sudo dnf remove.

• Disable the repo (or just delete the fitting .repo file below /etc/yum.repos.d/):

  yum-config-manager --disable remi-php74

• Enable the module:

  sudo dnf module install php:7.4
  dnf module list --installed

• List the packages provided by the module:

  dnf module info php:7.4

  Now reinstall the packages you need.