Where Is The Log File For The Jetmongod Service Located?

You can run the following command to get the location of the log file for the Jetmongod service: 

grep -Eiv "(^#.*|^$)" /usr/local/jetapps/etc/mongod.conf | grep -i log

systemLog:
logAppend: true
logRotate: reopen
path: /usr/local/jetapps/var/log/mongod/mongod.log

For more information about the service itself, you can refer to the following article: 

What is jetmongod?