Docker has been on my radar for quite some years now, but, I have to admit, as a C developer, I never really cared about it. I run Arch Linux on my computer, so everything I ever needed was packaged, save for a few exceptions where I could just whip up a custom PKGBUILD and install the resulting package. If I needed another OS, I used a VM.
But recently, I forced myself to try that container thingy (much like you'd try again some food you wrongly discarded as uninteresting when you were a child), and I found that I could find a few use cases for it, related to Varnish, of course. This post is a report of my exploration, so, don't expect too much new stuff, but since it's also focused on running Varnish inside a container, so there a few specific tricks and questions to be aware of.