Catalogsource dependency constraints

1. Proposed title of this feature request

Catalogsource dependency constraints

2. What is the nature and description of the request?

This request is to add a new type of constraint to OLM that would indicate that resolution should only prefer against a particular catalog or set of catalogs, instead of the default behavior where OLM performs resolution against all catalogs in the namespace and in the global catalog namespace by default.

This constraint may exist as part of the existing system, or be added as part of the standalone resolution work scoped for the v2 APIs and the deppy component.

3. Why does the customer need this? (List the business requirements here)

The main use-case for this feature currently is for SRE teams that are tasked with ensuring OLM is able to continue resolving dependencies in cases where catalog sources are unavailable. For example, a registry.redhat.io outage causes catalogs in the global namespace to become unavailable but does not impact local catalogs that rely on images hosted on a different registry (for example quay). In this scenario it is desirable for OLM to be able to continue resolving subscriptions pointing to those local catalogs and not error out due to global catalogs being unresponsive. See https://hackmd.io/BOA66e55QqG8XjBMIMFvIg?view for a concrete write-up of the specified use case.

4. List any affected packages or components.

OLM Resolver

operator-registry

Deppy