We'd like to continue this rather than invent a new way to send different kinds of settings to indexer. Can numReplicas be set this way or do you have some work to do on your side?
Yes, metakv is the preferred way to do this. Sorry about the confusion. It should already work, there is nothing additional to be done from indexer side.
if numReplicas is missing from the indexing config are you comfortable forever defaulting it to zero?
Yes, the setting has a default value of 0. If the setting is missing in metakv, indexer would use the default.
Another question : Some customers are already using this setting(as seen in the linked customer cases). In that case, Indexer would have already written the key "indexer.settings.num_replica" to metakv with some value. Will ns-server default to the value already existing in metakv or overwrite the metakv setting with 0 on upgrade?