Hi,

Recently we began using the sharding functionality of MongoDB and we have a cluster of several shards created through Mongo Cloud. The version of MongoDB is 3.2.7 (latest available at the moment).

We've hit a problem where if we set a readPrefernce to anything different than "primary" it works as "secondaryPreferred". In our case when "nearest" is set - the mongos service logs "secondaryPreferred".

We've been able to isolate this to a driver issue by writing a simple example in Node.js and in Python and monitoring the mongos log.

You can find the code examples and the respective logs attached.
(Obviously we've removed the actual server information)