Confused between HelmChart vs HelmRelease

[sidd-harth]

Hi,

I have been exploring Flux2 and trying the example around Helm.

I use either a GitRepository or HelmRepository to define the source and then do a HelmRelease.

What is the use of HelmChart API within the Source Controller? Why is HelmChart API part of Source Controller and not part of Helm Controller?

As per my understanding, a Source Controller connects and fetches artifacts from different sources. But within the below HelmChart example, it is using a sourceRef which can be mapped to HelmRepository | GitRepository | Bucket.

---
apiVersion: source.toolkit.fluxcd.io/v1beta2
kind: HelmChart
metadata:
  name: podinfo
  namespace: default
spec:
  interval: 5m0s
  chart: podinfo
  reconcileStrategy: ChartVersion
  sourceRef:
    kind: HelmRepository
    name: podinfo
  version: '5.*'

[hiddeco]

The HelmChart is part of the source-controller API because this controller deals with the handling (and caching) of artifacts. The reason it can refer to different types of sources is because the object type is capable of packaging charts from files (or folders) in these sources, in addition to it being able to do last-mile modifications on already packaged charts (from e.g. a HelmRepository) to overwrite the default values.yaml file.

See also the recent #3325 (comment) for additional information.

[sidd-harth]

Thanks for the response @hiddeco
Is my understanding correct as per the below image?

[hiddeco]

No, this is not correct.

The helm-controller creates a HelmChart object using the template defined in the HelmRelease. The source-controller then packages (or fetches) the chart using the Artifact it has (locally) available for the referenced Source, while taking things like values files into account which would require repackaging of an already packaged chart from e.g. a HelmRepository.

Once the HelmChart object has become Ready, the helm-controller will fetch this chart and use it to perform an install or upgrade using the further instructions of the .spec of the HelmRelease. This means the helm-controller only knows about the result of the HelmChart object, not about any of the other Source types.

Further values (the .spec.values and .spec.valuesFrom) are also calculated by the helm-controller itself and not injected into the packaged chart, but rather supplied while running the Helm action. As this may contain sensitive data due to values getting merged in from e.g. Secrets.

[crouth-redge]

So when would you want to use a HelmChart directly, if at all? The Docs are not clear about this, if they mention it at all.

[matheuscscp]

When you want to share the chart artifact in source-controller with multiple HelmReleases: https://fluxcd.io/flux/components/helm/helmreleases/#chart-reference