Make the `build` step of the Helm Chart conditional on OpenShift resources

[jmesnil]

Is your feature request related to a problem? Please describe.

By default, the Helm chart creates resources to build an application image from a Git repo using OpenShift S2I and BuildConfig resources. If an user does not want to build their image, they have to:

• disable the build step with build.enabled: false
• specify the name of the image with image.name

A user that wants to deploy on Kubernetes must manually do that. However, the Helm chart could be made smarter and handle this use case too.

If the cluster does not have the BuildConfig capability, it should not create any resources relate to building from S2I. There would no longer be a need for the user to manually disable it. If that's the case, then the image.name field becomes required and the installation must fail if it is not set.

The configuration matrix would become:

On OpenShift

• by default:
  • build.s2i.uri must be set and the application image is built with S2I
• set build.enabled to false to disable building and image.name is required

on Kubernetes

• by default:
  • image.name is required
• the whole build section is skipped

An user that wants to deploy a WildFly application on Kubernetes could use the simple value file:

image:
  name: my-app:latest

instead of the existing:

image:
  name: my-app:latest
build:
  enabled: false
deploy:
  route:
    enabled: false

(deploy.route.enabled is taking care of in #114 )