Proclet supports $PORT auto assignment in Proclet-0.30
proclet command (foreman for perl) that included in Proclet distribution, now supports auto assignment of $PORT that written in Procfile.
https://metacpan.org/release/Proclet
In Procfile
web: plackup -p $PORT -a app.psgi admin: plackup -p $PORT -a admin.psgi
web.1 would be assigned port 5000. admin.1 would be 5100. If you run 2 web processes, web.2 would be 5001.
You can change base TCP port number with -p option.
$ proclet -c web:2 -p 3000
Proclet、foremanと同じようにProcfileの$PORT自動割り当てに対応しました。