adjust warn if slow for removing docker volumes

[medyagh]

medmac@~/workspace/minikube (wait_sa2) $ ./out/minikube delete --all
❗  Executing "docker volume rm --force minikube" took an unusually long time: 2.095775097s
💡  Restarting the docker service may improve performance.

the warn should give a bit more time for removing a docker volume, that one is legit .
but for other tasks such as inspect, it should still warn more than 2 secs

// WarnIfSlow runs an oci command, warning about performance issues
func WarnIfSlow(arg ...string) ([]byte, error) {
	killTime := 15 * time.Second
	warnTime := 2 * time.Second

	ctx, cancel := context.WithTimeout(context.Background(), killTime)
	defer cancel()

	start := time.Now()
	glog.Infof("executing with %s timeout: %v", arg, killTime)
	cmd := exec.CommandContext(ctx, arg[0], arg[1:]...)
	stdout, err := cmd.Output()
	d := time.Since(start)
	if d > warnTime {
		out.WarningT(`Executing "{{.command}}" took an unusually long time: {{.duration}}`, out.V{"command": strings.Join(cmd.Args, " "), "duration": d})
		out.ErrT(out.Tip, `Restarting the {{.name}} service may improve performance.`, out.V{"name": arg[0]})
	}

	if ctx.Err() == context.DeadlineExceeded {
		return stdout, fmt.Errorf("%q timed out after %s", strings.Join(cmd.Args, " "), killTime)
	}
	if err != nil {
		if exitErr, ok := err.(*exec.ExitError); ok {
			return stdout, fmt.Errorf("%q failed: %v: %s", strings.Join(cmd.Args, " "), exitErr, exitErr.Stderr)
		}
		return stdout, fmt.Errorf("%q failed: %v", strings.Join(cmd.Args, " "), err)
	}
	return stdout, nil
}

[afbjorklund]

Why do we delete the docker volumes, when running e.g. the virtualbox driver ?

$ minikube start
😄  minikube v1.9.1 on Ubuntu 16.04
✨  Using the virtualbox driver based on user configuration
👍  Starting control plane node m01 in cluster minikube
🔥  Creating virtualbox VM (CPUs=2, Memory=2200MB, Disk=20000MB) ...
❗  Unable to verify SSH connectivity: dial tcp 192.168.99.100:22: i/o timeout. Will retry...
❗  Unable to verify SSH connectivity: dial tcp 192.168.99.100:22: i/o timeout. Will retry...
🐳  Preparing Kubernetes v1.18.0 on Docker 19.03.8 ...
🌟  Enabling addons: default-storageclass, storage-provisioner
🏄  Done! kubectl is now configured to use "minikube"
$ minikube delete
❗  Executing "docker volume prune -f --filter label=name.minikube.sigs.k8s.io=minikube" took an unusually long time: 15.004494256s
💡  Restarting the docker service may improve performance.
🔥  Deleting "minikube" in virtualbox ...
💀  Removed all traces of the "minikube" cluster.