# File lib/mongo/util/node.rb, line 166 def check_set_membership(config) if !config.has_key?('hosts') message = "Will not connect to #{host_string} because it's not a member " + "of a replica set." raise ConnectionFailure, message elsif config['hosts'].length == 1 && !config['ismaster'] && !config['secondary'] message = "Attempting to connect to an unhealthy, single-node replica set." raise ConnectionFailure, message end end