Add ClusterIP as a service option

[asimmons91]

This add an option to create a basic ClusterIP service when deploying with Cuber.

The idea here is to allow for some flexibility in how to expose a Cuber-managed app outside the cluster, but leave that for the user to setup outside of the Cuberfile.

In my case in particular I'm deploying my app in a k3s cluster that uses Traefik as the ingress controller and want to use customize the ingress to use host-based routing and cert-manager for SSL certificates.

Thanks for this awesome gem! 😄 It's saved me so much time & complexity compared to other ways of deploying on k8s!

[collimarco]

Thanks for the contribution!

One downside is that it looks like a "partial" or "incomplete" solution: you always need a third party component besides Cuber (e.g. install and manage and configure Traefik). In general I would prefer to rely only on the feature available in the standard Kubernetes distribution, without other external dependencies.