Purpose of config.ru (regarding server options), #245

["Matthias Wächter" <matthias@waechter.wiz.at>]

Hi,

Recently, I forked rack and created a feature 
[https://github.com/rack/rack/pull/245] that allows one to specify web 
server options as commands within config.ru, not only on the rackup 
command line or the comment line (#\) within config.ru. The need for 
this arises from new web server technologies like the ones typically 
used for Mongrel2 which need significantly more setup information than a 
simple Webrick or (legacy) Mongrel server.

Mongrel2 typically exchanges its web server requests and responses 
through *two* sockets, based on ZeroMQ, and these sockets can finally be 
Unix Domain Sockets which don’t waste the TCP socket address space. 
OTOH, in well-structured environments those IPC sockets need longer path 
names than a simple TCP port number, additionally it might be beneficial 
to use Ruby techniques to build up the IN and OUT IPC sockets based on 
some common pattern. Furthermore, Mongrel2 relies on a uuid setting for 
identifying sessions.

Setting all those options on the command line to a standalone rackup 
execution defeats its purpose, and setting them within the config.ru 
file inside the tiny littly comment line is ugly and cannot make use of 
Ruby constructs at all. So the idea was to let the newly created 
Rack::Builder object handle those options and hand it over to the 
calling process.

My change request, together with the necessary code and test changes, 
was rejected and closed right away by James with the comment

> config.ru is supposed to be portable and not bound to a particular server.

I wonder whether it’s James who doesn’t understand what I want, or 
whether it’s me who doesn’t understand what config.ru is supposed to be. 
I thought it is meant as a server configuration file: It

• defines which server technology to use (if there are multiple to 
choose from or if I want a specific solution),
• configures the used server, and
• defines which application and possible middleware to load.

The goal, as far as I got it, is to have the application and its setup 
bound together in a single configuration file, called config.ru. Sadly, 
the current syntax is only optimized for defining the application; the 
first two items on the list are handled via a clumsy comment line that 
gets longer the more options the web server requires for configuration.

So, can someone enlighten me, what’s the purpose of config.ru? Isn’t it 
supposed to carry the configuration for the web server as well?  Is it a 
bad idea to let Rack::Builder collect all these options within the 
config.ru body instead of the comment line?

– Matthias