In v3.4 your server would create a pid file with permissions 644. In v3.6 it creates a PID file with permissions 600. This means that unless my monitoring tool runs as root or as the mongod user I can not use this file to monitor the health of the service. In example this breaks PID file monitoring with datadog.

Solution is to just check for the existence of a process named 'mongod', but I don't prefer that as much as the pid file (because using a PID file is the way systemd does it). Would it be possible to change the permissions back to 644. There isn't anything really gained by making it 600 as far as I can tell (maybe I'm wrong... pray tell if so). At a minimum please change the permissions to 640 so I can put my monitoring service in the mongod group and then it can monitor the service that way.