Feature request: custom health checks for Helm releases

[mkjpryor]

Given that custom health checks have been proposed for Kustomizations, it would be good to have something equivalent for HelmReleases.

This is a feature gap when Flux is compared with Argo CD, which does have custom health checks for Helm installs.

HelmRelease currently relies on the logic that is part of helm upgrade --wait as a "health check". It is my understanding that this is not checked periodically, like Kustomization health checks, and the docs also suggest that it will not be triggered at all during drift correction (the docs imply that drift correct is done via patching, not a Helm operation).

The feature proposed here is that the same health check logic that applies for Kustomizations can be optionally applied to the manifest for HelmReleases via a flag in the spec.