Support retrieving hierarchical cluster topology #1306
Description
Is your feature request related to a problem? Please describe.
Helix cluster topology allows users to define multiple levels of domains. There is no restriction on the number of levels or the name of a specific domain. However, we do not have an API to retrieve the hierarchical cluster topology and the instances under each domain.
Describe the solution you'd like
Implement an API to retrieve hierarchical cluster topology so that users can easily get all the instances for a certain domain.