I think the concept of ConfigSets has become a bit confusing with the Config APIs (I'm thinking in SolrCloud mode here). Solr requires that a configset is pushed to ZooKeeper before creating a collection that uses it. It supports multiple collections using the same configset, which I think is great. You could also have a couple of configsets that no collection is currently using (who knows, maybe one that was recently deprecated, or that will be used soon, etc). This gives me the idea that configsets are a separate entity than the collection, not just a collection's configuration.
Config APIs allow you to operate on a collection to add handlers, change settings, etc. The problem is that you are not really applying the changes to the collection but to the complete configset. All collections using it will get the changes, and all of them will be reloaded after a change. Shouldn't those APIs be at a different level/outside the collection? Maybe a configset API? Or, maybe the configs (for example, the configoverlay.json) should only apply to the collection where the API call was made and not to other collections using the configset? Tomás
