Public bug reported:
Ubuntu 24.04.4 LTS
There appears to be a kernel networking/DNS regression between
6.8.0-137-generic and 6.8.0-138-generic affecting Docker containers.
After upgrading and booting kernel 6.8.0-138-generic, multiple unrelated
Docker containers fail DNS resolution through Docker's embedded DNS
resolver 127.0.0.11.
Examples:
CrowdSec:
lookup version.crowdsec.net on 127.0.0.11:53:
read udp ... ->127.0.0.11:53: i/o timeout
NetBird:
lookup pkgs.netbird.io on 127.0.0.11:53:
read udp ... ->127.0.0.11:53: i/o timeout
Watchtower:
lookup index.docker.io on 127.0.0.11:53:
read udp ... ->127.0.0.11:53: i/o timeout
The problem appeared immediately after upgrading to and booting
6.8.0-138-generic.
To verify the regression, I rebooted the same host using the previously
installed kernel 6.8.0-137-generic.
Without making any changes to Docker, the Docker networks, DNS
configuration or the affected containers, DNS resolution immediately
started working again.
Affected kernel:
6.8.0-138-generic
linux-image-6.8.0-138-generic 6.8.0-138.138
Working kernel:
6.8.0-137-generic
linux-image-6.8.0-137-generic 6.8.0-137.137
Affected kernel uname:
Linux dkr02 6.8.0-138-generic #138-Ubuntu SMP PREEMPT_DYNAMIC
Fri Jul 31 22:41:49 UTC 2026 x86_64 GNU/Linux
Steps to reproduce:
1. Boot the host with 6.8.0-138-generic.
2. Start the existing Docker containers.
3. DNS requests through Docker's embedded resolver 127.0.0.11 time out.
4. Reboot the identical host with 6.8.0-137-generic.
5. DNS resolution from the same Docker containers works again.
Expected result:
Docker container DNS resolution should continue to work after upgrading
from kernel 6.8.0-137 to 6.8.0-138.
Actual result:
With 6.8.0-138, DNS requests from multiple Docker containers time out
at Docker's 127.0.0.11 resolver.
The issue is reproducible by changing only the booted kernel.
** Affects: linux (Ubuntu)
Importance: Undecided
Status: New
--
You received this bug notification because you are a member of Ubuntu
Bugs, which is subscribed to Ubuntu.
https://bugs.launchpad.net/bugs/2166071
Title:
Regression in 6.8.0-138-generic: Docker embedded DNS 127.0.0.11 times
out, works with 6.8.0-137-generic
To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2166071/+subscriptions
--
ubuntu-bugs mailing list
[email protected]
https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
