Rails HTTP2 Server Push via Header Link (on Cloudflare)

http2-server-push.rb

class ApplicationController < ActionController::Base

  after_action :server_push_headers # https://twitter.com/connorjshea/status/728472354385317888

  def server_push_headers
    # CLoudflare HTTP2 Server Push: https://blog.cloudflare.com/announcing-support-for-http-2-server-push-2/
    if request.format.html? # only on html pages
      layout = self.send(:_layout) # with the right layout
      if layout == "main" || layout == "speaker" || layout == "admin" 
        assets = [
          "<#{view_context.asset_path('application.css')}>; rel=preload; as=style",
          "<#{view_context.asset_path('application.js')}>; rel=preload; as=script",
          "<#{view_context.asset_path("twitter/bootstrap/glyphicons-halflings.png")}>; rel=preload; as=image",
          "<#{view_context.asset_path("site/#{site.code}/logo.png")}>; rel=preload; as=image",
        ]
        assets.push([
          "<#{view_context.asset_path("ppc/check.png")}>; rel=preload; as=image",
          "<#{view_context.asset_path("icons/ratings/star-off.png")}>; rel=preload; as=image",
        ]) if params[:controller] == 'speakers' && params[:action] == 'show'
        response.headers['Link'] = assets
      end
    end
  end

end