Ensure server + replicaset metrics are pulled for local host, not using 'read preference'

Author: naemono

lib/sensu-plugins-mongodb/metics.rb

@@ -376,6 +376,7 @@ def get_mongo_client(db_name)
         address_str = "#{host}:#{port}"
         client_opts = {}
         client_opts[:database] = db_name
+        client_opts[:connect] = :direct
         unless db_user.nil?
           client_opts[:user] = db_user
           client_opts[:password] = db_password