mongodb on OSX : how to update brew service to start with auth?

Question

I installed mongodb with homebrew. I added an admin , and I updated the /usr/local/etc/mongod.conf to enable the security authorisation.

I can start mongod with auth:

mongod --auth --port 27017 --dbpath   /usr/local/var/mongodb

But starting service :

brew services start mongodb

does not start with auth ...

how can I do it ?

thanks !!