Is it possible to to rewrite the base URL in Sinatra?

Is it possible to to rewrite the base URL?

E.g. instead of www.host.com/ to use www.host.com/blah/ as a base url and so:

get '/' do
  ...
end

would work for www.host.com/blah/

I could append to all my routes '/blah/..' but any gems etc. 开发者_StackOverflow中文版would fail to work as well.

This can be done in Rails easily and I would like to have it in Sinatra as well.

I use a rack middleware for this rack-rewrite and I am quite happy with it :)

    use Rack::Rewrite do
      rewrite %r{^/\w{2}/utils}, '/utils'
      rewrite %r{^/\w{2}/ctrl},  '/ctrl'
      rewrite %r{^/\w{2}/},      '/'
    end

EDIT:

Not sure if I understand your problem, but here are a config.ru file

# encoding: utf-8
require './config/trst_conf'
require 'rack-flash'
require 'rack/rewrite'

use Rack::Session::Cookie, :secret => 'zsdgryst34kkufklfSwsqwess'
use Rack::Flash
use Rack::Rewrite do
  rewrite %r{^/\w{2}/auth},  '/auth'
  rewrite %r{^/\w{2}/utils}, '/utils'
  rewrite %r{^/\w{2}/srv},   '/srv'
  rewrite %r{^/\w{2}/},      '/'
end

map '/auth' do
  run TrstAuth.new
end
map '/utils' do
  run TrstUtils.new
end
map '/srv' do
  map '/tsk' do
     run TrstSysTsk.new
  end
  map '/' do
    run TrstSys.new
  end
end
map '/' do
  run TrstPub.new
end

and an example Sinatra::Base subclass

# encoding: utf-8

class TrstAuth < Sinatra::Base

  # Render stylesheets
  get '/stylesheets/:name.css' do
    content_type 'text/css', :charset => 'utf-8'
    sass :"stylesheets/#{params[:name]}", Compass.sass_engine_options
  end

  # Render login screen
  get '/login' do
    haml :"/trst_auth/login", :layout => request.xhr? ? false : :'layouts/trst_pub'
  end

  # Authentication
  post '/login' do
    if user = TrstUser.authenticate(params[:login_name], params[:password])
      session[:user] = user.id
      session[:tasks] = user.daily_tasks
      flash[:msg] = {:msg => {:txt => I18n.t('trst_auth.login_msg'), :class => "info"}}.to_json
      redirect "#{lang_path}/srv"
    else
      flash[:msg] = {:msg => {:txt => I18n.t('trst_auth.login_err'), :class => "error"}}.to_json
      redirect "#{lang_path}/"
    end
  end

  # Logout
  get '/logout' do
    session[:user] = nil
    session[:daily_tasks] = nil
    flash[:msg] = {:msg => {:txt => I18n.t('trst_auth.logout_msg'), :class => "info"}}.to_json
    redirect "#{lang_path}/"
  end

end

maybe this helps :) full source on github.

In a before block you can edit env['PATH_INFO]`; Sinatra will then use the edited value for routing.

For your example, something like this might work...

before do
    env['PATH_INFO'].sub!(/^\/blah/, '')
end

I agree with the other answers that using a middleware component is a more robust solution but if you want something concise and simple, that works inside the Sinatra app instead of via config.ru, then munging the Rack environment is not bad.

You could have a look at https://github.com/josh/rack-mount, maybe that one can help you out?