document docker in kata

[egernst]

We should document how to run docker from within a Kata container.

This addresses kata-containers/runtime#358

[egernst]

/cc @jcvenegas FYI - see egernst@4bfb22b

[grahamwhaley]

I have some dibs on what we call this.... along the lines of 'dind' for Docker-In-Docker ... I reckon....
Docker-In-Kata is 'dink'
Kata-In-Kata is 'kink'

:-)

[jodh-intel]

Let's stop dinking around and see how kinky boots! 😄

[jcvenegas]

@egernst @grahamwhaley have you consider use CONFIG_OVERLAY_FS=y by default in our kernel, or you think is not an strong usecase to enable it?

[grahamwhaley]

@jcvenegas it's not been on my radar before - is that something we need to have for DinK to work? If so, we can for sure consider adding it.

[jcvenegas]

@grahamwhaley looking to @egernst commit seems that is the recommended fs to use and builds a kernel manually. Probably we can make the process less painful if we add it by default.

[egernst]

related issue: kata-containers/runtime#1429

[AkihiroSuda]

Docker-in-Kata doesn't seem to make sense for security, until Kata get support for --privileged without exposing host devices kata-containers/runtime#1568