Add support for VM-free deployments using Docker

[tstromberg]

This will give a much better user experience for folks in nested VM's than the "none" driver currently provides.

If possible, this should be done in collaboration with the fine folks at https://github.com/kubernetes-sigs/kind

[afbjorklund]

Do we really have to write multiple implementations, or can we use something like CRI from the start ?

Like https://kind.sigs.k8s.io/docs/design/principles#target-cri-functionality (and to avoid that extra work)

[afbjorklund]

See this kind Dockerfile for some of the crazy stuff needed, when running systemd in a container:
https://github.com/kubernetes-sigs/kind/blob/master/images/base/Dockerfile (based on Ubuntu)

• https://kind.sigs.k8s.io/docs/design/base-image
• https://kind.sigs.k8s.io/docs/design/node-image

This issue (VM-free deployments) is likely to have to work with changes to libmachine and buildroot...
As in: it is not certain that we will keep the docker-machine API and the minikube ISO, while doing it.

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The "none" driver isn't really a VM-free environment, it's just intended to run on a pre-allocated VM.

This issue is different, since it doesn't require the user to do anything but provide a container runtime.
Then it will start containers "faking" nodes, and use those to start pods. (see e.g. the kind design doc)

That is something else than installing the kubelet on the local host. It also allows for multiple nodes.

[afbjorklund]

See also https://github.com/kubernetes/community/blob/master/contributors/design-proposals/cluster-lifecycle/local-cluster-ux.md for the original minikube proposal and some of the reasoning behind it...

[afbjorklund]

@medyagh : will you run a sshd in the "node" container, or should we use exec and nsenter instead ?

I was wondering about the minikube ssh use-case, as you know it is not supported by the none driver

• https://blog.docker.com/2014/06/why-you-dont-need-to-run-sshd-in-docker/

• https://blog.phusion.nl/2015/01/20/baseimage-docker-fat-containers-treating-containers-vms/

[medyagh]

I would user exec, which will invoke "docker exec"

I am implementing a specialized commander for the vm-free which is basically a helper for docker exec

[priyawadhwa]

This feature is expected to be done by next quarter.

[medyagh]

the undocumented support for docker vm driver has been merged by #6151

I will close this issue and make smaller issues to be tracked for next steps of kic