Similar to the image I created yesterday, I now have a Stubby + Dnsmasq Docker image. This builds upon the work of the previous image, but I am pleased I spent time on it as I used this opportunity to optimise the Docker build process by looking into multi-stage builds. I am very pleased I got that working … I have a better understanding of how Docker works and appreciate the Docker way of doing things. I also spent some time thinking how to store the data for this image as I wanted a way to store the Dnsmasq config somewhere yet not require rebuilding the image each time I had a change (which is how I was doing things earlier). Now I am using Docker volumes to separate the data out, and the same changes are applied to the Stubby + Unbound image too.
Containers should just work out of the box and be throwaway. That’s what I have aimed for here. Out of the box it will provide DNS resolution, but I can configure it to do DHCP and local zones etc. and this config is stored in a Docker volume. I chose to go with a Docker volume than map to some location on a filesystem to abstract things away. As I had alluded to in an earlier post I like Docker volumes over manually specifying a location.
I also took the time to figure out a bit more of s6 in terms of reloading a service. With Dnsmasq I needed a way of sending it a signal to reload, so I added a script to easily do that via
docker exec. Oh I love
docker exec! :)