Running CoreDNS as a Forwarder in Kubernetes

Sat, 13 Jan 2018 10:38:37 +0000

This post details how I got CoreDNS running as a forwarder in a Kubernetes cluster. There were several problems that stood in the way of this goal:

Having (and building) a cluster out of Raspberry PIs.
Making load balancing possible in a non-cloud environment.
- See https://github.com/google/metallb.
Extending CoreDNS with a plugin that could communicate with 9.9.9.9 using DNS-over-TLS.
- See https://github.com/coredns/forward.
Building arm docker containers on amd64.
- See https://github.com/miekg/dxbuild.
Having a (simple) CI system to build (Docker) images and version the k8s manifests.
- No published repository, see various gists referenced in this document.

Cluster

I bought 4 PIs, some nice Corkea cases, an Anker USB power supply and power- and network cables. Then it is just a matter if putting everything together and building the cluster.

Docker Alpine Linux Image for ARM

Mon, 25 May 2015 15:25:00 +0000

Alpine Linux is a super small Linux distribution which targets Docker. The only downside is that they use musl libc instead of glibc, which causes some issues for Golang programs. But I want this as a base image for SkyDNS on my Raspberry Pi, running HypriotOS.

After reading a modest amount of documentation I found the mkimage-alpine.sh script which build a docker image ala alpine, but makes it possible to select different archs. I had to tweak this script a little to make it do what I want, but after that it worked.

Arm on Miek Gieben

Running CoreDNS as a Forwarder in Kubernetes

Cluster

Docker Alpine Linux Image for ARM