support extra manifests

[vijaybandari]

• Provide a way to add extra manifests to manage as single release instead of creating them outside.

Our use case - we share our cluster to external teams thorugh VPC Endpoints and the load balancer has to be managed outside. So we use targetGroupBinding CRD to route traffic to the co-ordinator service. These resources are created manually outside of helm deployment.
Having all resources for an application in one place is ideal and i see this is a common in most of community charts.

[nineinchnick]

I don't get it. Why can't you just deploy another chart?

[lozbrown]

I don't get it. Why can't you just deploy another chart?

You can, or add additional templates to this chart before deploying.

But this this is a common flexibility that is often added to application charts and keeps all customisations in values files making upgrades easier.

[vijaybandari]

@nineinchnick to keep the application's helm values in one place as said by @lozbrown
It's common across majority of the helm charts.

[vijaybandari]

@nineinchnick
We manage our secrets using argocd vault plugin, so the kubernetes secrets are created as part of the helm chart. That way everything is one place, without the extraManifest we have to either we create them manually or create a separate helm chart to manage them through gitops.
Also we use TargetGroupBinding for binding tagets on a Load Balancers due to the way our internal DNS works (no R53).

So these kind of resources will go under extranManifest and the whole deployment is managed with one helm chart and one values file.

Submitted the PR #398.