[feature] Support for local helm charts

[fritzduchardt]

While using ytt is great, it is not as well known as helm and in some cases sticking to helm reduces complexity and makes it easier to introduce myks. Therefore, we could introduce a new folder type in prototypes that contains local charts, e.g.:

prototypes:
  my-app:
    helm
    vendir
    ytt
    **chart**

The chart folder would contain a local helm chart in the standard format:

chart:
  templates
  Chart.yaml
  Chart.lock
  values.yaml

When rendering, the local charts would be templated and added to the remote chart (if there is one).

[Zebradil]

What about having local charts in a shared space? The example can be placed in repo/charts/my-app in the repository root (repo probably should be named differently).

With the following vendir config (when #191 gets merged):

apiVersion: vendir.k14s.io/v1alpha1
kind: Config
directories:
- path: charts/my-app
  contents:
  - path: .
    directory:
      path: repo/charts/my-app

I believe that complex prototypes should reside outside of the myks configuration tree. They should probably have their own life cycle. They will be also more reusable when they reside outside of myks' prototypes directory — they can be even used on their own! :-)

[fritzduchardt]

What I am aiming for is a simplification. Some potential users of myks might appreciate it. Consider a setup where you use external secrets to extract secrets from Vault and put them into the cluster. With that you have plenty of split deployments that consist of one app for the application and a tiny one for the secrets. If now the team feels shy to use ytt, because they are struggling to digest the rest of the setup, having a local chart would be the next best thing.

[Zebradil]

Consider a setup where you use external secrets to extract secrets from Vault and put them into the cluster. With that you have plenty of split deployments that consist of one app for the application and a tiny one for the secrets.

Sorry, I'm not familiar with the external secrets. What do you mean by "split deployments"? Why there would be "a tiny one for the secrets"?

Could you also address this question?

[fritzduchardt]

After discussion I agree that the case for this feature is not quite as compelling as I though.