Migrate CentOS 8 to Rocky Linux 9

Rocky Linux was started for exactly the hosts on this page: CentOS 8 machines left without updates when CentOS 8 ended in December 2021. migrate2rocky converts CentOS 8 in place, but only to Rocky Linux of the same major release, and Rocky does not support in-place upgrades between major releases. Taking a host to Rocky Linux 9 is a rebuild either way.

vrtmv makes the rebuild the plan: it reads the CentOS 8 host, translates its packages, services and settings to Rocky Linux 9, and builds a fresh host. Most renames on this move are libraries, fonts and desktop packages that Fedora renamed upstream before RHEL 9 picked them up.

Where CentOS 8 stands

CentOS 8 reached its end of life in December 2021.

Packages that change name

Of the packages the Index translates for this move, these arrive on Rocky Linux 9 under another name. vrtmv installs the new name and carries the configuration across; nothing on the old host is renamed by hand.

• golang-github-prometheus-alertmanager becomes alertmanager.
• fontpackages-filesystem becomes fonts-filesystem.
• fwupdate becomes fwupd.
• gnome-themes-standard becomes gnome-themes-extra.
• google-crosextra-carlito-fonts becomes google-carlito-fonts.
• libguestfs-tools-c becomes guestfs-tools.
• iptables and iptables-services become iptables-nft and iptables-nft-services.
• glassfish-jaxb-api becomes jaxb-api.
• khmeros-battambang-fonts becomes khmer-os-battambang-fonts.
• network-scripts becomes NetworkManager. EL9 removed the network-scripts package (deprecated at EL8).
• prometheus-node-exporter becomes node-exporter.
• SDL becomes sdl12-compat.

Services that change

• network.service is replaced by NetworkManager.service: the enabled service is moved to its successor, not left pointing at a unit that no longer exists.

Repositories

The packages come from AppStream, BaseOS and Extras, enabled by default. CRB is available but off; the plan says when a package needs it turned on. Vendor repositories the source used are named in the plan, not silently enabled.

What needs your decision

vrtmv does not guess at these. Each one is a line on the plan's punch list, for you to settle before the rebuild runs.

• Network configuration kept in ifcfg files with custom scripts around them. NetworkManager reads the files, but hooks that called the old network service need replacing.

What the parity run showed

vrtmv's conformance run for this pair read the inventory from a real CentOS 8 disk, planned the move and applied the plan to a fresh Rocky Linux 9 system. All 51 packages the plan promised were installed on the target, and all 11 carried configuration files landed. Your parity report gives the same accounting for your own hosts.

Should this become a container?

Usually not. A container image runs one command, with no init and no scheduler, on the kernel of the machine it runs on. A CentOS 8 host that runs one long-lived service, keeps its data in directories you can mount as volumes and reads its config from files is a candidate for one; start the image and test that service before you plan a cutover on it. A host that runs several services, keeps a database on its own disk or runs cron jobs is better rebuilt as a Rocky Linux 9 machine, which is what vrtmv does by default.

Before you choose, vrtmv assess runs its container feasibility checks on the source (kernel modules, the entrypoint, local state, scheduled jobs and software no package installed) and prints what each one found. The full fit lists, and what breaks after the image runs.

How vrtmv does it

vrtmv reads the CentOS 8 host without an agent and changes nothing on it. The Index translates its packages, services and settings to Rocky Linux 9, and the plan lists every change and every decision before anything runs. The new host is built from that plan, and the parity report compares it with the old one, so you can show an auditor what came across.

Questions about this move

Does vrtmv upgrade CentOS 8 to Rocky Linux 9 in place?

No. vrtmv reads the CentOS 8 host without an agent and changes nothing on it. It builds a fresh Rocky Linux 9 host from the plan, so the old host keeps running until you cut over, and it stays your way back.

Which packages change name on Rocky Linux 9?

13 of the packages the Index translates for this move arrive on Rocky Linux 9 under another name, for example golang-github-prometheus-alertmanager becomes alertmanager and fontpackages-filesystem becomes fonts-filesystem. vrtmv installs the new name and carries the configuration across, and the plan lists each one.

Does Rocky Linux 9 need a subscription?

No. The packages come from AppStream, BaseOS and Extras, enabled by default. CRB needs no subscription either.

Is CentOS 8 still supported?

CentOS 8 reached its end of life in December 2021.

How do I show that the Rocky Linux 9 host matches the old one?

With the parity report. vrtmv verify checks the rebuilt host against the plan, from its package database and the carried configuration paths, and exits non-zero on any parity gap, so cutover can be gated on it. Keep the source inventory, the plan and the report with the change record.

Read next

• Install vrtmv: one static binary, checked against its signature.
• vrtmv migrate: the plan, and the role that builds the new host.
• vrtmv verify: the parity report.
• Container output: what decides whether vrtmv writes a Containerfile.
• Pricing: what a migration costs after the free ones.
• Rocky Linux vs AlmaLinux: which should you actually run?
• Every migration guide