[Epic] Implement polling for tag-based catalogs

[joelanford]

Overview

The design of OLM is such that catalog data is expected to be updated regularly and be pushed repeatedly to the location already specified in a Catalog object (e.g. spec.source.image.ref) such that users of the catalogs can consume updates without having to explicitly ask for a different catalog image.

In order to support this use case, catalogd needs to support an API to enable polling the catalog's source to check to see if new data is available, and if so, to pull it and make it available on the cluster.

If a catalog source is content-addressable (e.g. if the spec.source.image.ref is digest-based), polling should be disabled. We should discuss what (if anything) should happen if a user attempts to configure polling when they have specified a content-addressable catalog source.

Design Documents

• RFC https://docs.google.com/document/d/1iWSrWL9pYRJ5Ua3VYErkK1Q2lAusBUeDCh66Ew4lDbQ/edit?usp=sharing

Task List

• Enable polling for content for Image Source

[everettraven]

The linked issues are closed and this functionality is implemented. Closing this issue.