The kubeconfig generated by docker.io/rancher/k3s:v0.10.2 or earlier
sets the cluster.server address to 127.0.0.1. Previously this seems to
have been localhost. And we only replace localhost with the correct
address for our local kubeconfig.
The error this can lead to:
```
$ k3d --version
k3d version v1.3.4
$ docker-machine --version
docker-machine version 0.16.1, build cce350d7
$ docker --version
Docker version 19.03.1, build 74b1e89
$ k3d create
INFO[0000] Created cluster network with ID 649d6f34b84a4df16d2524f0ea0ce69cd4f964a79ae56e2a07bb1ee11d1fce50
INFO[0001] Add TLS SAN for 192.168.99.100
INFO[0001] Created docker volume k3d-k3s-default-images
INFO[0001] Creating cluster [k3s-default]
INFO[0001] Creating server using docker.io/rancher/k3s:v0.10.2...
INFO[0001] Pulling image docker.io/rancher/k3s:v0.10.2...
INFO[0018] SUCCESS: created cluster [k3s-default]
INFO[0018] You can now use the cluster with:
export KUBECONFIG="$(k3d get-kubeconfig --name='k3s-default')"
kubectl cluster-info
$ export KUBECONFIG="$(k3d get-kubeconfig --name='k3s-default')"
$ kubectl cluster-info
To further debug and diagnose cluster problems, use 'kubectl cluster-info dump'.
The connection to the server 127.0.0.1:6443 was refused - did you specify the right host or port?
```
The kubeconfig.yaml generated by K3S uses local host as the host name by
default. It won't work when running with docker machine.
This patch detects if the docker environment is set up with docker
machine. If it is, then replace the host name to the IP address of
the docker machine.
Add the basic frame work for supporting spawning a bash shell by cli
command.
With this change, we can spawn a bash shell in the context of a cluster
$ k3d create -n my-cluster
$ k3d bash -n my-cluster
[my-cluster] $>
// execute commands with KUBECONFIG already set up
[my-cluster] $> kubectl get pods
