Rails live streaming sample

non-streaming-headers

$ curl localhost:8080 -I

HTTP/1.1 200 OK
Content-Type: text/html
ETag: "0f8cca87cff164a57033f54d75dc1288"
Cache-Control: max-age=0, private, must-revalidate
X-Runtime: 0.017000
Server: Jubilee(2.1.0)
Transfer-Encoding: chunked
Date: Thu, 24 Jul 2014 14:38:03 GMT

rails.ru

require "action_controller/railtie"
require "rails/test_unit/railtie"

class HelloWorld < Rails::Application
  routes.append do
    root "hello#world"
    get "/stream" => "my#stream"
  end

  config.cache_classes = true
  config.eager_load = true
  config.secret_key_base = "49837489qkuweoiuoqwehisuakshdjksadhaisdy78o34y138974xyqp9rmye8yrpiokeuioqwzyoiuxftoyqiuxrhm3iou1hrzmjk"

  ["Rack::Lock", "ActionDispatch::Flash", "ActionDispatch::BestStandardsSupport",
   "Rack::Sendfile", "ActionDispatch::Static", "Rack::MethodOverride",
   "ActionDispatch::RequestId", "Rails::Rack::Logger",
   "ActionDispatch::ShowExceptions", "ActionDispatch::DebugExceptions",
   "ActionDispatch::RemoteIp", "ActionDispatch::Callbacks",
   "ActionDispatch::Cookies",  "ActionDispatch::Session::CookieStore",
   "ActionDispatch::ParamsParser", "Rack::Head", "Rack::ConditionalGet"].each do |middleware|
    config.middleware.delete(middleware)
  end

end
class MyController < ActionController::Base
  include ActionController::Live

  def stream
    response.headers['Content-Type'] = 'text/event-stream'
    100.times {
      response.stream.write "hello world\n"
      sleep 1
    }
  ensure
    response.stream.close
  end
end

streaming-headers

$ curl localhost:8080/stream -I

HTTP/1.1 200 OK
X-Frame-Options: SAMEORIGIN
X-XSS-Protection: 1; mode=block
X-Content-Type-Options: nosniff
X-UA-Compatible: chrome=1
Content-Type: text/event-stream
Cache-Control: no-cache
X-Runtime: 0.019000
Server: Jubilee(2.1.0)
Transfer-Encoding: chunked
Date: Thu, 24 Jul 2014 14:38:15 GMT

Rack::Etag has no effect on the streaming request at all!

Common scenario -- masking the underlying storage (S3, GCS, Rackspace etc.) via authenticated API urls to our own backend. So something like curl our-app.com/videos/123/download should start streaming the video immediately after receiving the first chunk of the file fetched from the underlying storage.

So, are you open to making a similar GIST for binary files?