Add fog_options to configuration to be passed to fog #create

We found that uploading large files to S3 would result in a socket error
("connection reset by peer") occasionally and lately much more
consistently. In researching this I saw that many people got this error
when uploading too large of a file without multipart chunking. I would
have assumed fog did this automatically but the default chunk size may
be too high. In order to address this I wanted to drop the chunk size to
100MB.

Rather than hard-code this I opted to expose a `fog_option`
configuration option that lets me pass any additional options I want to
the fog's `#create` call. This is similar to the `fog_attributes` option
implemented in CarrierWave which [addresses the same
problem](http://stackoverflow.com/a/11867978/201911).

We've been running this now for a week in production and it seems to
resolve the issue.

#2135

NEWS

@@ -1,5 +1,7 @@
 master:
 
+* Improvement: Add `fog_options` configuration to send options to fog when
+  storing files.
 * Drops support to end-of-life'd ruby 2.0.
 * Improvement: Paperclip now supports aws-sdk v2
   @betesh, @davetchen,

lib/paperclip/storage/fog.rb

@@ -33,6 +33,10 @@ module Storage
     #   that is the alias to the S3 domain of your bucket, e.g.
     #   'http://images.example.com'. This can also be used in
     #   conjunction with Cloudfront (http://aws.amazon.com/cloudfront)
+    # * +fog_options+: (optional) A hash of options that are passed
+    #   to fog when the file is created. For example, you could set
+    #   the multipart-chunk size to 100MB with a hash:
+    #     { :multipart_chunk_size => 104857600 }
 
     module Fog
       def self.extended base
@@ -98,12 +102,14 @@ def flush_writes
           log("saving #{path(style)}")
           retried = false
           begin
-            directory.files.create(fog_file.merge(
+            attributes = fog_file.merge(
               :body         => file,
               :key          => path(style),
               :public       => fog_public(style),
               :content_type => file.content_type
-            ))
+            )
+            attributes.merge!(@options[:fog_options]) if @options[:fog_options]
+            directory.files.create(attributes)
           rescue Excon::Errors::NotFound
             raise if retried
             retried = true

spec/paperclip/storage/fog_spec.rb

@@ -484,6 +484,25 @@ def custom_method
           assert_equal @dummy.avatar.fog_credentials, @dynamic_fog_credentials
         end
       end
+
+      context "with custom fog_options" do
+        before do
+          rebuild_model(
+            @options.merge(fog_options: { multipart_chunk_size: 104857600 }),
+          )
+          @dummy = Dummy.new
+          @dummy.avatar = @file
+        end
+
+        it "applies the options to the fog #create call" do
+          files = stub
+          @dummy.avatar.stubs(:directory).returns stub(files: files)
+          files.expects(:create).with(
+            has_entries(multipart_chunk_size: 104857600),
+          )
+          @dummy.save
+        end
+      end
     end
 
   end