[v2] Support namespaced ProviderConfigs

[jbw976]

(broken out from #6280)

Today all ProviderConfigs are cluster scoped. With namespaced MRs, I expect folks would benefit from both cluster scoped and namespaced ProviderConfigs. The way you could create a 'global default' ProviderConfig for all namespaces at the cluster scoped, or specific ProviderConfigs limited to one namespace.

In the v2 compatible preview of provider-upjet-aws, we do have namespaced ProviderConfig types, but they are not finalized and no code is actually using them yet.

The final types should look like this, similar to how we approached Usage.protection.crossplane.io:

• ClusterProviderConfig.aws.m.crossplane.io - Cluster scoped
• ProviderConfig.aws.m.crossplane.io - Namespaced
• ProviderConfig.aws.upbound.io - Legacy cluster scoped

This issue depends on #6457, e.g. for "MRs should be able to reference either cluster scoped or namespaced ProviderConfigs via spec.providerConfigRef".

There are a few places in the upjet provider code bases that need to be updated to be aware of namespaced ProviderConfigs:

• clients.SelectTerraformSetup
• clients.provider_config.go has lots of code still using cluster scoped ProviderConfigs
• (there are probably others too...)

We can consider adding an internal ProviderConfig type that the clients use, and converting to that type from the namespaced/cluster types as needed. This idea needs more thought and exploration.

ProviderConfig usage tracking likely needs to be updated to support namespaced resources as well.

[negz]

What we want is for v2 MRs to support this:

spec:
  providerConfigRef:
    kind: ClusterProviderConfig
    name: default    

Or alternatively:

spec:
  providerConfigRef:
    kind: ProviderConfig
    name: default    

I don't think we want namespace, as namespaced MRs should only be able to use ProviderConfigs from their namespace. I don't think we want apiVersion either since it'll be different from provider to provider - you couldn't really tell an AWS MR to go use a GCP ProviderConfig for example.

I met with @ erhancagirici today and suggested we just add kind to all MRs, including v1 Legacy MRs. After writing up #6457 (comment) I think we should just do that instead though. So legacy MRs only have name.

[erhancagirici]

addressed in:
crossplane-runtime introduces new ProviderConfigReference type that is inlined in v2.ManagedResourceSpec. crossplane/crossplane-runtime#854
angryjet generates v2-style providerconfig refs for PCUs and MRs: crossplane/crossplane-tools#114

Providers should implement handling of different PC kinds, possibly using type switches.