Upgrading Buster LTS (10) to Bookworm (current stable) concerns

[Nick Sal]

Hi,

I plan to upgrade a server running Buster to Bookworm.
Server is running: {web,mail} servers, mysql and postregre, docker, ssh, ldap, ferm (firewall), and few other non-critical services.

I'd like to appeal to your experience for a couple concerns:

1) Should I upgrade in two steps from Buster to Bullseye (oldstable), and then to Bookworm? Or should I go directly from Buster to Bookworm in one step?
The upgrade will be done by changing sources.list

2) To the best of your knowledge, do docker images break between such upgrades? Unfortunately, I don't have many details on docker because it was set-up by a previous admin.

If any big break/incompatibility comes to mind for the above services, please don't hesitate to share your story :)

Cheers!
Nick

[Michael Kjörling]

Post by Nick Sal
1) Should I upgrade in two steps from Buster to Bullseye
(oldstable), and then to Bookworm? Or should I go directly from
Buster to Bookworm in one step?
The upgrade will be done by changing sources.list

NEVER skip major Debian releases during an upgrade cycle. Doing so is
unsupported and can lead to any number of problems.

Treat each major version upgrade (10 -> 11; 11 -> 12) as a separate
upgrade. I would go as far as to suggest letting the system run on, in
this case, Debian 11 for a while before proceeding to the upgrade to
12, to catch any issues that take a while to manifest themselves.

[Jeffrey Walton]

Post by Nick Sal
I plan to upgrade a server running Buster to Bookworm.
Server is running: {web,mail} servers, mysql and postregre, docker, ssh, ldap, ferm (firewall), and few other non-critical services.
1) Should I upgrade in two steps from Buster to Bullseye (oldstable), and then to Bookworm? Or should I go directly from Buster to Bookworm in one step?
The upgrade will be done by changing sources.list

If I recall correctly, simply changing sources.list is not
recommended. That's because there are post-upgrade scripts that should
be run to finalize a configuration on occasion.

You should follow
<https://www.debian.org/releases/bullseye/amd64/release-notes/ch-upgrading.en.html>,
<https://www.debian.org/releases/stable/amd64/release-notes/ch-upgrading.en.html>
and friends.

Post by Nick Sal
2) To the best of your knowledge, do docker images break between such upgrades? Unfortunately, I don't have many details on docker because it was set-up by a previous admin.
If any big break/incompatibility comes to mind for the above services, please don't hesitate to share your story :)

Jeff