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2020-05-23 - Oof… DNS!

*.minikube.randomroad.net and *.minikube.randomroad.net. aren't much different, but the small difference wasted an hour of my time yesterday.

I have a domain for my home-lab / messing around stuff, and I host DNS for it on 2 small NetBSD VPS servers. This is using BIND9, replication and DNSSEC are setup, and everything is usually nice and easy.

Yesterday I was doing some work that inolved a Kubernetes development setup needing a bunch of hostnames that would all resolve to the IP address of my local Minikube VM. Rather than /etc/hosts entries I thought I would add a wildcard on a subdomain in the BIND9 zone file for my domain, so I wrote…

; Minikube
*.minikube.randomroad.net      IN      A       192.168.39.129

… and then signed the zone file, restarted named, and assumed all would be well. Cue almost an hour of looking into errors appearing in my containers like…

dial tcp: lookup cloud.minikube.randomroad.net: Temporary failure in name resolution

I could go to that address in my browser fine. I could ping it fine. But in the containers running under Minikube it didn't resolve.

Turns out that it's easy to overlook a trailing period in a zone file. The zone file is for randomroad.net so a *.minikube.randomroad.net entry without a trailing period really means *.minikube.randomroad.net.randomroad.net. I didn't catch on to this quickly due to being able to ping the hostname fine on my host, outside of Kubernetes. Naturally I'd previously put an entry in /etc/hosts some time ago and forgotten about that.

After bashing my head against the desk it just needed a quick change of the zone file to…

; Minikube
*.minikube      IN      A       192.168.39.129

… or …

; Minikube
*.minikube.randomroad.net.      IN      A       192.168.39.129

… and all was right in the world again.

Simple mistakes made to look more complicated than they are, due to something you did and forgot about, are always fun!


This post is day 18 of my #100DaysToOffload challenge.

If you want to get involved, you can get more info from https://100daystooffload.com.


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