How can I disable MongoDB log messages in console?

This logging is coming from the Ruby Mongo driver. The default logging level seems to be Logger::DEBUG. Change it to something higher to disable the debug output:

Mongo::Logger.logger.level = Logger::FATAL

To make the driver log to a logfile instead:

Mongo::Logger.logger       = Logger.new('mongo.log')
Mongo::Logger.logger.level = Logger::INFO

Note that if you’re using the Mongoid ODM, then you may want to adjust logging there too:

Mongoid.logger       = Logger.new('mongoid.log')
Mongoid.logger.level = Logger::INFO 

For Rails + Mongoid in application.rb:

config.mongoid.logger = Logger.new(Rails.root + '/log/mongoid.log', :warn)

# ...or change the logging level without a new file destination
config.mongoid.logger.level = Logger::INFO