Tailscale on Linux host breaks all dns on docker containers

SUPPORT QUESTIONS
1

Tailscale version:

1.34.2
tailscale commit: 1f08176933ce9387f3bf3f428b975a7a08861a93
other commit: 56304b5392d4acd4e2555f91b74166c8a64a8d8f
go version: go1.19.4-tse6ce5b5003

Your operating system & version:
x64 Debian 11 bullseye fully updated

I’m new to Tailscale and I’m running into an issue where dns inside docker containers stops working which breaks functionality.

I have a bunch of docker containers setup and working fine for months. I then recently installed Tailscale on the host machine. I setup Tailscale to use NextDNS and on that Debian machine I setup Tailscale to be a exit node.

After a few hours I noticed some of the apps I have running in docker stopped working. Digging around a little bit I discovered that dns no longer works inside the containers. Stopping Tailscale and restarting the containers fixes the issue.

My networking skills are limited and I have no idea what causes this or how I can fix it. Any suggestions?

Thanks!

2

This is happening to me as well. Once MagicDNS is enabled with the abiliity to use local override, it messes up everything.

3

This is because docker copies over the host resolv.conf configuration file (Container networking | Docker Documentation) which tailscale rewrites (Why is resolv.conf being overwritten? · Tailscale) when MagicDNS is running on the host.

What’s slightly annoying is that I have systemd-resolved installed, which should stop tailscale from rewriting that file - but tailscale does not seem to be picking it up!