Mongo hosts is your replicaset URL tyk_analytics is the DB name.
You can’t set it centrally, they are separate here because Pump is plugable and we use the pumps interface like all other pumps and they don’t share configs.
Just to be explicitly clear then, in your example above where you have
"mongo_url": "mongo-hosts/tyk_analytics"
The value “mongo-hosts/tyk_analytics” is just place holder text rather than the actual contents of the file. It is not “looking up” the value declared in a different config section/file ?