Ruby Rack change port

Question

I have a Ruby web API and using Rack, the config.ru file looks like this:

#\ -p 8080 -o 0

run App::API

It works well, but if I want to change port for web server using rackup arguments it won't work. It seems the first line parameters in config.ru override the command line arguments. I couldn't find anything on Rack documentation that explains this behaviour.

The question is if I execute Rack server like this:

bundle exec rackup -p 8000

I expect it to bind to port 8000 but it still binds to port 8080 . How can I change the port without changing the config.ru file?

Answer 1

So I decided to submit a pull request for Rack to fix this weird behaviour. Reading the code I realized something very strange, the code should work as I expected :|

It favours command line arguments over config file ( config.ru )! Digging into code commits reveals that this changes are not merged into any stable version yet ( 1.6.4 ). It's actually in version 2.0.0.alpha . Which is obviously not production ready.

Here is the commit: https://github.com/rack/rack/commit/d924f8074e0b3d6c49881c33f983ef323258a941#diff-b578c27b65b1d4a848181b8c1ca082fdL300

So the answer is: it's not possible in 1.x versions and I should either change config.ru or forget about that :(