Document $PORT and $PS

[mike-burns]

Update the ronn documentation to explain that $PORT and $PS exist and
that $PORT starts as the base port number and is incremented on each
line.

[mike-burns]

Hey @ddollar, just a polite nudge about this.

[mike-burns]

Ping @ddollar . Anything to know that you've seen this is welcome.

[mike-burns]

@ddollar is this repo still used?

[ddollar]

Thanks!

[gorenje]

Hi @ddollar,

I've been happily using foreman for a long time now but what is the rationale behind adding 100 to the port for each line in a Procfile?

I just discovered this by having this strange effect:

prompt> PORT=1234 foreman start web
....
stdout> web.1    | [42390] * Listening on tcp://0.0.0.0:1334

i.e. PORT value was strangely 100 higher than I intended.

This was my Procfile:

worker: bundle exec sidekiq -C config/sidekiq.yml -r ./application.rb
web: bundle exec puma -p ${PORT:-8080} -C config/puma.rb

i.e. web process on line 2, not the first line.

So in order to get the right port, I had to define the web process on the first line of my Procfile:

PORT=1234 foreman start web
....
web.1    | [43088] * Listening on tcp://0.0.0.0:1234

(Having swapped the two lines of my Procfile.)

This is incredibly subtle. I don't understand how the PORT variable can vary according to line on which something is defined in the Procfile.

I guess this is covering PORT number overlapping when starting multiple services in a single Procfile. But I would have assumed this would be an application responsibility, i.e. the application decides what to do if an PORT is taken and not foremans concern.