MongoDB packages are shipped with logging enabled in configuration but without a script to rotate the logfile. There are two build-in ways to let MongoDB rotate its logfile. You can execute db.runCommand("logRotate"); from the mongo shell or kill -SIGUSR1 $(cat /var/lib/mongodb/mongod.lock) from unix shell.

The best way to automate this is to use logrotate. Copy the following code into /etc/logrotate.d/mongodb and make sure that pathes and filenames in the script correspond with those in your system.

/var/log/mongodb/mongodb.log {
    daily
    rotate 7
    compress
    missingok
    notifempty
    sharedscripts
    postrotate
        /bin/kill -SIGUSR1 `cat /var/lib/mongodb/mongod.lock` && 
        rm -f /var/log/mongodb/mongodb.log.????-??-??T??-??-??
    endscript
}

It rotates the logfile /var/log/mongodb/mongodb.log on a daily basis and keeps them for 7 days compressed. Since MongoDB’s build-in logRotate conflicts with logrotate, it also cleans up the empty, log-rotated files created by MongoDB.