Support Rack::Sendfile middleware

Author: lfidnl

CHANGELOG.md

@@ -11,6 +11,7 @@
 * [#1252](https://github.com/ruby-grape/grape/pull/1252): Allow default to be a subset or equal to allowed values without raising IncompatibleOptionValues - [@jeradphelps](https://github.com/jeradphelps).
 * [#1255](https://github.com/ruby-grape/grape/pull/1255): Allow param type definition in `route_param` - [@namusyaka](https://github.com/namusyaka).
 * [#1257](https://github.com/ruby-grape/grape/pull/1257): Allow Proc, Symbol or String in `rescue_from with: ...` - [@namusyaka](https://github.com/namusyaka).
+* [#1280](https://github.com/ruby-grape/grape/pull/1280): Support `Rack::Sendfile` middleware - [@lfidnl](https://github.com/lfidnl).
 * [#1285](https://github.com/ruby-grape/grape/pull/1285): Add a warning for errors appearing in `after` callbacks - [@gregormelhorn](https://github.com/gregormelhorn).
 * Your contribution here.
 

README.md

@@ -2328,6 +2328,30 @@ class API < Grape::API
 end
 ```
 
+If you want to take advantage of `Rack::Sendfile`, which intercepts responses whose body is
+being served from a file and replaces it with a server specific X-Sendfile header, specify `to_path`
+method in your file streamer class which returns path of served file:
+
+```ruby
+class FileStreamer
+  # ...
+
+  def to_path
+    @file_path
+  end
+
+  # ...
+end
+```
+
+Note: don't forget turn on `Rack::Sendfile` middleware in your API:
+
+```ruby
+class API < Grape::API
+  use Rack::Sendfile
+end
+```
+
 ## Authentication
 
 ### Basic and Digest Auth

lib/grape.rb

@@ -131,6 +131,7 @@ module Util
     autoload :InheritableSetting
     autoload :StrictHashConfiguration
     autoload :FileResponse
+    autoload :SendfileResponse
   end
 
   module DSL

lib/grape/middleware/formatter.rb

@@ -35,7 +35,7 @@ def build_formatted_response(status, headers, bodies)
         headers = ensure_content_type(headers)
 
         if bodies.is_a?(Grape::Util::FileResponse)
-          Rack::Response.new([], status, headers) do |resp|
+          Grape::Util::SendfileResponse.new([], status, headers) do |resp|
             resp.body = bodies.file
           end
         else

lib/grape/util/sendfile_response.rb

@@ -0,0 +1,19 @@
+module Grape
+  module Util
+    # Response should respond to to_path method
+    # for using Rack::SendFile middleware
+    class SendfileResponse < Rack::Response
+      def respond_to?(method_name, include_all = false)
+        if method_name == :to_path
+          @body.respond_to?(:to_path, include_all)
+        else
+          super
+        end
+      end
+
+      def to_path
+        @body.to_path
+      end
+    end
+  end
+end

spec/grape/integration/rack_sendfile_spec.rb

@@ -0,0 +1,44 @@
+require 'spec_helper'
+
+describe Rack::Sendfile do
+  subject do
+    send_file = file_streamer
+    app = Class.new(Grape::API) do
+      use Rack::Sendfile
+      format :json
+      get do
+        file send_file
+      end
+    end
+
+    options = {
+      method: 'GET',
+      'HTTP_X_SENDFILE_TYPE' => 'X-Accel-Redirect',
+      'HTTP_X_ACCEL_MAPPING' => '/accel/mapping/=/replaced/'
+    }
+    env = Rack::MockRequest.env_for('/', options)
+    app.call(env)
+  end
+
+  context do
+    let(:file_streamer) do
+      double(:file_streamer, to_path: '/accel/mapping/some/path')
+    end
+
+    it 'contains Sendfile headers' do
+      headers = subject[1]
+      expect(headers).to include('X-Accel-Redirect')
+    end
+  end
+
+  context do
+    let(:file_streamer) do
+      double(:file_streamer)
+    end
+
+    it 'not contains Sendfile headers' do
+      headers = subject[1]
+      expect(headers).to_not include('X-Accel-Redirect')
+    end
+  end
+end

spec/grape/middleware/formatter_spec.rb

@@ -282,4 +282,14 @@ def to_xml
       end
     end
   end
+
+  context 'send file' do
+    let(:app) { ->(_env) { [200, {}, @body] } }
+
+    it 'returns Grape::Uril::SendFileReponse' do
+      @body = Grape::Util::FileResponse.new('file')
+      env = { 'PATH_INFO' => '/somewhere', 'HTTP_ACCEPT' => 'application/json' }
+      expect(subject.call(env)).to be_a(Grape::Util::SendfileResponse)
+    end
+  end
 end