The problem is that Rails ActionController::Streaming renders directly into a Chunked::Body. This means the content is first chunked and then gzipped by the Rack::Deflater middleware, instead of gzipped and then chunked.
According to the HTTP/1.1 RFC 6.2.1, chunked must be last applied encoding to a transfer.
Since "chunked" is the only transfer-coding required to be understood
by HTTP/1.1 recipients, it plays a crucial role in delimiting messages
on a persistent connection. Whenever a transfer-coding is applied to a
payload body in a request, the final transfer-coding applied must be
"chunked".
I fixed it for us by monkey patching ActionController::Streaming _process_options and _render_template methods in an initializer so it does not wrap the body in a Chunked::Body, and lets the Rack::Chunked middleware do it instead.
module GzipStreaming
def _process_options(options)
stream = options[:stream]
# delete the option to stop original implementation
options.delete(:stream)
super
if stream && env["HTTP_VERSION"] != "HTTP/1.0"
# Same as org implmenation except don't set the transfer-encoding header
# The Rack::Chunked middleware will handle it
headers["Cache-Control"] ||= "no-cache"
headers.delete('Content-Length')
options[:stream] = stream
end
end
def _render_template(options)
if options.delete(:stream)
# Just render, don't wrap in a Chunked::Body, let
# Rack::Chunked middleware handle it
view_renderer.render_body(view_context, options)
else
super
end
end
end
module ActionController
class Base
include GzipStreaming
end
end
And leave your config.ru as
require ::File.expand_path('../config/environment', __FILE__)
use Rack::Chunked
use Rack::Deflater
run Roam7::Application
Not a very nice solution, it will probably break some other middlewares that inspect/modify the body. If someone has a better solution I'd love to hear it.
If you are using new relic, its middleware must also be disabled when streaming.
