add public controller interface

[joejulian]

#653 moved the helmrelease controller to internal. We built our own operator around this controller. This adds a stable public wrapper around the internal controllers.

Applies to #699, redpanda-data/redpanda#13088

[hiddeco]

Besides my comment, I would prefer the HelmReleaseReconcilerFactory to contain a comment about usage not being advised nor supported by the project itself, and it being available on a "best-effort basis".

More specifically because it can result in the consumer their controller fighting a helm-controller instance if e.g. sharding (or namespace selection) is not properly configured (or available).

In addition to issues around the life-cycle of Custom Resource Definitions, and most likely any other hidden surprise which can arise when a custom built controller and a helm-controller are deployed in the same cluster.

[joejulian]

More specifically because it can result in the consumer their controller fighting a helm-controller instance if e.g. sharding (or namespace selection) is not properly configured (or available).

In addition to issues around the life-cycle of Custom Resource Definitions, and most likely any other hidden surprise which can arise when a custom built controller and a helm-controller are deployed in the same cluster.

The contention can be handled by not reconciling resources that have an owner reference by default. When our controller creates the resources, it'll set the owner reference to the (in our case) Redpanda resource. If a helmrelease, for example, is created in any normal fashion, it won't have an owner reference. #769

Please comment on that issue if you think this would be an acceptable approach and I can (or I can get someone to) work on it.

[stefanprodan]

I don’t think we should allow others to reconcile helm.toolkit.fluxcd.io resources. Redpanda should use their own API group. By allowing this, we undermine the FluxCD users, on clusters with the redpanda controller they can’t use Flux, which feels very wrong to me.

[joejulian]

We already have users that use both.