Add apiserver logs to "minikube logs" command

[tstromberg]

This way users can see flag misconfiguration errors.

[tstromberg]

Here's the command for the docker runtime:

minikube ssh 'docker logs $(docker ps -a -f name=k8s_kube-api --format={{.ID}})'

It's unclear yet how to handle this for containerd and CRIO.

[aaron-prindle]

There are some open questions about the implementation here:

• currently minikube logs supports an -f flag to tail logs. If multiple components are being output, is there a sane way to tail them both? Is it reasonable to no longer support tailing logs?
• does it make sense to add flag options so that you can output only specific pieces, eg: minikube logs --kubelet and minikube logs --apiserver, with minikube logs being all components
• in the joint output, should there be some kind of delineation so that users know what component the logs refer to, eg: "=====APISERVER_LOGS=====" (is there a more standard way to do this?)

[tstromberg]

@aaron-prindle - It's possible to sanely tail multiple logs, though you bring up a good point that we would want to be able to filter different ones in the future for this mode in particular. I actually implemented this in https://github.com/kubernetes/minikube/pull/3551/files - I closed the PR because it added some unrelated changes, but planned to resubmit it for review once I could update it for merge conflicts.

I agree about the delineation. I don't think there is much in the way of standardization, but now that I think about it, the tail command uses this form when called for multiple files:

==> /etc/ttys <==

If you are interested in this issue, you are welcome to assign it to yourself and take the PR to completion. I got blocked trying to figure out how to get pod logs for non-Docker runtimes - but I assume crictl or podman could help out here.

[afbjorklund]

Should probably be using crictl for this, it is a mandatory requirement (nowadays) and is supposed to know how to talk to different CRI ? However, it doesn't have the --format option available

[afbjorklund]

sudo crictl logs $(sudo crictl ps -a --name kube-apiserver | tail -n +2 | cut -f1 -d' ')

[afbjorklund]

@tstromberg : using podman wouldn't really help for docker, just like docker wouldn't help for cri-o