Additional Option for registry-creds

[Teddy-Schmitz]

I would like to add an additional config option to the addon setup prompts that show up when you enable registry-creds. Specifically I would like the option to set the gcr-url to something other then the default without having to edit the replication controller.

I'm happy to do a PR on this if thats ok.

[aaron-prindle]

We will gladly accept a PR for this. Currently the gcr-url is a CLI arg into the addon:
https://github.com/upmc-enterprises/registry-creds/blob/master/main.go#L57

The code for the prompt to input parameters into the addon is here:

minikube/cmd/minikube/cmd/config/util.go

Line 121 in 9b539db

enableGCR := AskForYesNoConfirmation("\nDo you want to enable Google Container Registry?", posResponses, negResponses)

You should be able to edit the addon to take a Config Map that passes the gcr-url parameter as a command line arg:
https://kubernetes.io/docs/user-guide/configmap/

[Teddy-Schmitz]

Great, I'll start with adding the config map option to the addon.