Nameserver Limits Exceeded Warning

[CapitanMurloc]

Nameserver limits were exceeded, some nameservers have been omitted, the applied nameserver line is: 2a01:4ff:ff00::add:1 2a01:4ff:ff00::add:2 185.12.64.2.

kubectl get events -n kube-system

Warning DNSConfigForming pod/coredns-74fb7c7dfd-7wxxf

I don't think anything is wrong because it's a Warning, but I tried to solve it and couldn't. Is it a k3s configuration problem or a hetzner problem or is it something I'm doing wrong?

Does anyone else have this problem?

[vitobotta]

Never come across this but generally speaking to reduce load on CoreDNS I always recommend to install NodeLocal DNS Cache

https://kubernetes.io/docs/tasks/administer-cluster/nodelocaldns/

[vitobotta]

I'm gonna convert this into a discussion since it's not an issue with the tool.

[CapitanMurloc]

The cause is due to the netplan, if you look at the path /etc/netplan/50-cloud-init.yaml it configures the IPv6 and also adds two DNS servers. If you look at /etc/resolv.conf you will see that you will have a total of 4 DNS servers, this causes your k3s to emit a constant event indicating that you have exceeded the number of DNS servers. To stop this event, simply edit /etc/netplan/50-cloud-init.yaml by deleting one of the two addresses in the nameservers section and then apply netplan apply. This makes /etc/resolv.conf to be configured correctly. Do you think you can apply this here in your repository? In my case I finally had to use ansible. But if you do it from here it would be better.

[vitobotta]

Hi, and sorry - somehow I didn't get a notification of your reply so I didn't notice it before. I will add a note in the README about @d3473r 's solution for this since it's OS specific so I cannot generalise the change in the code. Thanks for reporting about the cause.

[d3473r]

Hello, we hit the same problem.
We fixed it with the following post create command removing the second nameserver from the netplan config

post_create_commands:
  - sed -i "/2a01:4ff:ff00::add:2/d" /etc/netplan/50-cloud-init.yaml
  - netplan apply

Regards

[vitobotta]

Hi, and thanks! I took a note to add a note to the README about it since it's OS specific, so it may be required or not depending on the OS the user chooses. I am surprised I have never come across this though. Which OS are you using?

[d3473r]

Hi, for me this is happening with Ubuntu 22.04, see the Kubernetes known issues: https://kubernetes.io/docs/tasks/administer-cluster/dns-debugging-resolution/#known-issues

[vitobotta]

Thanks!

[Aubermean]

Me too, ubuntu 22.04