Upgrading single-node PVE 8.3.3 to 9: any gotchas with LXC containers?

[ciarandwi]

Hi all,

I'm planning to upgrade our only Proxmox host from PVE 8.3.3 (Debian 12, kernel 6.8.12-8-pve) to PVE 9, and before I do I'd like to hear about other people's experiences.

Setup:

• Single node, no cluster, on a Scaleway dedicated server
• 7 unprivileged LXC containers (Ubuntu 22.04, and one on 26.04): Rails apps, a database, Redis, a search engine, and nginx
• No VMs and no Ceph
• Host firewall with iptables (iptables-persistent), with Tailscale installed on the host

My plan:

1. Update to the latest 8.4 and run pve8to9 --full
2. Take a vzdump backup of every container (done, copied off the server)
3. Switch the package sources to Trixie, run apt dist-upgrade, then reboot out of hours

Questions:

• Has anyone had LXC containers fail to start after the upgrade, especially older Ubuntu ones?
• Any problems with iptables-persistent or Tailscale on the host after moving to Trixie?
• Any network config changes, such as interface names changing, that could lock me out?
• Is it worth doing a practice run on a spare server first, or is an in-place upgrade usually painless for a simple setup like this?

Thanks in advance!

 

[UdoB]

Just to be sure, you know that page? --> https://pve.proxmox.com/wiki/Upgrade_from_8_to_9
I followed it multiple times and it worked in every single case.

But I can not answer your question nevertheless - I am using only a very few LXCs, sorry.

You may install PVE9 in a VM. (Ignore possibly warnings regarding missing CPU features - containers should work.) Then restore your backups in there. That would be a very good pre-upgrade test!

 

[jdancer]

When PVE 8 was going EOL in one-week, I backed up the /etc directory and existing LXCs (don't run any VMs) via the native backup functionality.

Did a clean install of PVE 9 and restored the LXCs. LXCs came up with no issues.

I didn't do an upgrade because didn't want to deal with a one-off cases with networking and having to blacklist the Infiniband module of the Mellanox ConnectX-3 NIC.

Already been running PVE 9 at work, so that was a good training on-ramp.

Irregardless of the operating system (Windows, Linux, macOS, whoever), in-place upgrades of major OS versions always seem to backfire on me. Guess you can blame it on Murphy's Law. I seem to spend more time troubleshooting then just doing a backup, clean install, then a restore. YMMV.