What is the purpose of HelmRepository.spec.interval when there is a HelmChart.spec.interval

[VTimNeumann]

I was wondering what the purpose of the required HelmRepository.spec.interval when all Helm Charts also have an interval (by setting HelmRelease.spec.chart.spec.interval or leaving it empty, which causes it to default to HelmRelease.spec.interval).

As I understand, both are used to check for updates of the charts in the repository.
Obviously the interval on each chart governs the update checking for that chart only, whereas the one on the repository does check for updates in the whole repository.
But as all charts have such an interval, it seems to me the one on the repository is redundant.

See https://fluxcd.io/flux/components/source/api/v1beta2/#source.toolkit.fluxcd.io/v1beta2.HelmRepository
See https://fluxcd.io/flux/components/helm/api/v2beta2/#helm.toolkit.fluxcd.io/v2beta2.HelmChartTemplate

[souleb]

The interval is used as a reconciliation period. Each custom resource is reconciled by a different controller.
For a HelmRepository the principal action is retrieving and persisting the helm index.
For a HelmChart it is about retrieving the right chart based on the helm index provided by the corresponding HelmRepository. Different intervals will give different results as you may have a different view of the helm repository.

[VTimNeumann]

Ok thanks a lot. One more question: Assuming I'm not using an OCI repo, is there any point in setting the HelmChart reconciliation to be more frequent than the HelmRepository reconciliation? (I've seen tutorials where 12h for the chart and 24h for the repo have been used)

[souleb]

I'd make the HelmRepository frequency lower to make sure to catch updates before the chart reconciliation.

[VTimNeumann]

Do you mean you'd have a lower interval for the repo?
I.e. HelmRepository.spec.interval: 6h and HelmRelease.spec.chart.spec.interval: 12h
Or did you actually mean a lower frequency => higher period == higher interval for the repo?
I.e. HelmRepository.spec.interval: 24h and HelmRelease.spec.chart.spec.interval: 12h

[souleb]

Oh sorry, yes lower interval.

[antonblr]

When:

• HelmRepository sync interval is 6h
• HelmRelease sync interval is 12h

Assuming I just build and pushed a new Helm release.

What would happen in case if I update and push a new HelmRelease.spec.chart.spec.version to the Git repository?
From my understanding it will try to reconcile HelmRelease right away (because of change), but it won't find a new Helm release version until HelmRepository reconciliation loop happens, where it updates the index (which can be up to 6 hours). Is this correct assumption?

Or, perhaps HelmRepository will be reconciled in the same wave, because notification-contoller will send an event of Git repo push?