From the forever documentation, you can define a forever log file with the following forever options.
options:
-l LOGFILE Logs the forever output to LOGFILE
-o OUTFILE Logs stdout from child script to OUTFILE
-e ERRFILE Logs stderr from child script to ERRFILE
so you would do something like this:
forever start -l /path/to/log/forever.log -o /path/to/log/myapp.log -e /path/to/log/myapp_error.log
you can then configure your log.io harvester
logStreams: {
myapp: [ "/path/to/log/myapp.log", "/path/to/log/myapp_error.log", "/path/to/log/forever.log" ]
},