If an application can't be installed on a cluster, provide an explanation in addition to disabling the button

Problem to solve

I was confused as to why the "Install" button was disabled when installing JupyterHub on my Kubernetes cluster:

The explanation is provided in the documentation (I needed to install Ingress first), but it would be nice to have this requirement directly in the UI.

Original Proposal

If an application can't be installed, render a descriptive message in the UI (either in an informational alert or a tooltip) in addition to disabling the "Install" button.

Solution

Have an enabled button, allow the user to hit install, and then throw a validation telling the user what they need to do (in this case, Install Ingress first)

To install JupyterHub, you must first install Ingress.