Location of logstash.yml using brew?

Hi I am a new user to logstash but could not work out where to put logstash.yml?

$brew install logstash

Am I supposed to generate this file?

The settings that are present in logstash.yml can also be specified as command line flags.

You can do logstash --help this will show you all the command line flags that can be supplied to logstash.