http proxymachine api brainstorm

gistfile1.rb

# load balancing
#   send incoming requests to one of 10 backends running on ports 5000-5009
HttpProxyMachine.start do
  { :host => 'localhost', :port => 5000 + rand(10) }
end

# host based routing
#   send requests for media.server/file to localhost:3000/media/file
#   all other requests are unmodified
HttpProxyMachine.start do |request|
  uri =
    if request.headers['host'] == 'media.server'
      "/media/#{request.path}"
    else
      request.path
    end

  { :host => 'localhost', :port => 3000, :uri => uri }
end

# path based routing
#   requests to /static.* go to static.local
#   requests to /images.* go to images.local
#   all other requests go to rails.local
HttpProxyMachine.start do |request|
  {
    :host =>
      case request.uri
      when %r|^/static|
        'static.local'
      when %r|^/images|
        'images.local'
      else
        'rails.local'
      end
  }
end

# sticky sessions
#   use incoming cookie to select previous backend, or pick a random one
#   add/update the outgoing cookie to reflect the chosen backend
HttpProxyMachine.start(proc do |request|
  if cookie = request.cookies['backend_port']
    port = cookie.to_i
  else
    port = 5000 + rand(10)
  end

  { :host => 'localhost', :port => port }
end, proc do |response, options|
  response.cookies['backend_port'] = options[:port]
end)

# instrumentation
#   measure the time taken by the backend and add a header to the response
HttpProxyMachine.start(proc do |request|
  { :port => 3000, :start_time => Time.now }
end, proc do |response, options|
  response.headers['X-Response-Time'] = Time.now - options[:start_time]
end)

# basic auth
#   require valid basic-auth headers before proxying to localhost:80
HttpProxyMachine.start do |request|
  if auth = request.headers['authorization'] and valid?(auth)
    { :host => 'localhost' }
  else
    { :reply => [401, {'WWW-Authenticate' => 'Basic realm="local"'}, "Auth required."] }
  end
end

# ssl proxy
#   add ssl encryption layer on localhost:443 to an unsecured backend on localhost:3000
HttpProxyMachine.start(:port => 443, :ssl => true) do |request|
  request.headers['X-Forwarded-Proto'] = 'https'
  request.headers['X-Real-IP'] = request.remote_addr
  { :host => 'localhost', :port => 3000, :ssl => false }
end

# method transformation
#   change DELETE /path requests to GET /path/delete
HttpProxyMachine.start do |request|
  if request.http_method == 'DELETE'
    { :port => 3000, :method => 'GET', :uri => request.uri + "/delete" }
  else
    { :port => 3000 }
  end
end

I like it.

where is HttpProxyMachine located?

@knoopx: There is no implementation, only this brainstorm for an API. This should be possible to build on top of https://github.com/tmm1/http_parser.rb