SOLR-11299 outlines an approach to using a collection Alias to refer to a series of collections of a time series. We'll need to store some metadata about these time series collections, such as which field of the document contains the timestamp to route on.
The current /aliases.json is a Map with a key collection which is in turn a Map of alias name strings to a comma delimited list of the collections.
If we change the comma delimited list to be another Map to hold the existing list and more stuff, older CloudSolrClient (configured to talk to ZooKeeper) will break. Although if it's configured with an HTTP Solr URL then it would not break. There's also some read/write hassle to worry about – we may need to continue to read an aliases.json in the older format.
Alternatively, we could add a new map entry to aliases.json, say, collection_metadata keyed by alias name?
Perhaps another very different approach is to attach metadata to the configset in use?