In theory, we can execute 'k3d bash' again within an cluster shell. I
can't think of any practical value for allowing this capability.
On the contrary, this can lead to confusion to the user.
This patch adds a simple mechanism to detect and block recursive bash
invocation.
In addition to provide an interactive shell, this patch adds the
'--command' and '-c' options to allow user to issue a command in the
context of a cluster.
For example:
$ k3d bash -c 'kubectl cluster-info'
OS distribution and user may choose to install bash in different path.
This patch uses bash found by "$PATH" environment, rather than hard code
the bash path.
This patch also handle the case 'bash' are not found. Mostly likely due
to bash not being supported by the platform, or it is not installed.
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
