CoreOS support

[kaplan-michael]

Support for coreOS distro family.

Closes: #107

[kke]

Too bad there's no coreos image for footloose so we could add it to the test matrix. I assume you've tried this build with an actual coreos installation? :)

[kke]

I assume it will need some directory tweaks to avoid writing to /usr?

[kaplan-michael]

I'm running my cluster on coreos for a while. kubelet has to have writable path, so example config it would be:

calico:
  flexVolumeDriverPath: /var/libexec/k0s/kubelet-plugins/volume/exec/nodeagent~uds

controllerManager:
  extraArgs:
    flex-volume-plugin-dir: /var/libexec/k0s/kubelet-plugins/volume/exec
workerProfiles:
  - name: coreos
    values:
      volumePluginDir: /var/libexec/k0s/kubelet-plugins/volume/exec

[till]

Maybe to add:

When you create a profile, you also need to add the following:

spec:
  hosts:
    - role: worker
      installFlags:
        - "--profile coreos"

[bephinix]

@kke A few month ago, I have added support for Flatcar Container Linux which is also part of the CoreOS-Family. To support the installation of K0S using K0SCTL, we added support for overwriting the actual binary path. If this is added to this PR (or to a new PR), can we get this merged? I think this should be straight-forward. :100:

Ref.: https://github.com/k0sproject/k0sctl/pull/221

[kaplan-michael]

@bephinix I finally have more time for this, so I'll try to redo this PR, so we can merge it.

[kaplan-michael]

@bephinix @kke I have used your reference and updated it to the spec so we can finally merge this. Please check it after me, as I haven't tested this yet(will try doing that tomorrow).

Thanks!

[kaplan-michael]

forgot to import errors there(should be fixed now)

[kke]

Looks fine to me, I assume you've used it succesfully?

[kaplan-michael]

Looks fine to me, I assume you've used it succesfully?

Yes, I have successfully deployed a simple cluster with it.