S3 CNAME support

lib/paperclip/attachment.rb

@@ -346,6 +346,10 @@ module Paperclip
       return true if callback(:"#{which}_#{name}_post_process") == false
     end
 
+    def callback which #:nodoc:
+      instance.run_callbacks(which, @queued_for_write){|result, obj| result == false }
+    end
+
     def post_process_styles
       log("Post-processing #{name}")
       @styles.each do |name, args|
@@ -362,10 +366,6 @@ module Paperclip
       end
     end
 
-    def callback which #:nodoc:
-      instance.run_callbacks(which, @queued_for_write){|result, obj| result == false }
-    end
-
     def interpolate pattern, style = default_style #:nodoc:
       interpolations = self.class.interpolations.sort{|a,b| a.first.to_s <=> b.first.to_s }
       interpolations.reverse.inject( pattern.dup ) do |result, interpolation|

lib/paperclip/storage.rb

@@ -108,11 +108,18 @@ module Paperclip
     #   Paperclip will attempt to create it. The bucket name will not be interpolated.
     #   You can define the bucket as a Proc if you want to determine it's name at runtime.
     #   Paperclip will call that Proc with attachment as the only argument.
-    # * +url+: There are two options for the S3 url. You can choose to have the bucket's name
+    # * +url+: There are three options for the S3 url. You can choose to have the bucket's name
     #   placed domain-style (bucket.s3.amazonaws.com) or path-style (s3.amazonaws.com/bucket).
+    #   Lastly, you can specify a CNAME (which requires the CNAME to be specified as
+    #   :s3_cname. You can read more about CNAMEs and S3 at 
+    #   http://docs.amazonwebservices.com/AmazonS3/latest/index.html?VirtualHosting.html
     #   Normally, this won't matter in the slightest and you can leave the default (which is
     #   path-style, or :s3_path_url). But in some cases paths don't work and you need to use
     #   the domain-style (:s3_domain_url). Anything else here will be treated like path-style.
+    #   NOTE: If you use a CNAME for use with CloudFront, you can NOT specify https as your
+    #   :s3_protocol; This is *not supported* by S3/CloudFront. Finally, when using the host
+    #   alias, the :bucket parameter is ignored, as the hostname is used as the bucket name
+    #   by S3.
     # * +path+: This is the key under the bucket in which the file will be stored. The
     #   URL will be constructed from the bucket and the path. This is what you will want
     #   to interpolate. Keys should be unique, like filenames, and despite the fact that
@@ -129,8 +136,12 @@ module Paperclip
           @s3_permissions = @options[:s3_permissions] || 'public-read'
           @s3_protocol    = @options[:s3_protocol]    || (@s3_permissions == 'public-read' ? 'http' : 'https')
           @s3_headers     = @options[:s3_headers]     || {}
+          @s3_host_alias  = @options[:s3_host_alias]
           @url            = ":s3_path_url" unless @url.to_s.match(/^:s3.*url$/)
         end
+        base.class.interpolations[:s3_alias_url] = lambda do |attachment, style|
+          "#{attachment.s3_protocol}://#{attachment.s3_host_alias}/#{attachment.path(style).gsub(%r{^/}, "")}"
+        end
         base.class.interpolations[:s3_path_url] = lambda do |attachment, style|
           "#{attachment.s3_protocol}://s3.amazonaws.com/#{attachment.bucket_name}/#{attachment.path(style).gsub(%r{^/}, "")}"
         end
@@ -154,6 +165,10 @@ module Paperclip
         @bucket
       end
 
+      def s3_host_alias
+        @s3_host_alias
+      end
+
       def parse_credentials creds
         creds = find_credentials(creds).stringify_keys
         (creds[ENV['RAILS_ENV']] || creds).symbolize_keys

test/storage_test.rb

@@ -37,6 +37,55 @@ class StorageTest < Test::Unit::TestCase
     end
   end
 
+  context "" do
+    setup do
+      rebuild_model :storage => :s3,
+                    :s3_credentials => {},
+                    :bucket => "bucket",
+                    :path => ":attachment/:basename.:extension",
+                    :url => ":s3_path_url"
+      @dummy = Dummy.new
+      @dummy.avatar = StringIO.new(".")
+    end
+
+    should "return a url based on an S3 path" do
+      assert_match %r{^http://s3.amazonaws.com/bucket/avatars/stringio.txt}, @dummy.avatar.url
+    end
+  end
+  context "" do
+    setup do
+      rebuild_model :storage => :s3,
+                    :s3_credentials => {},
+                    :bucket => "bucket",
+                    :path => ":attachment/:basename.:extension",
+                    :url => ":s3_domain_url"
+      @dummy = Dummy.new
+      @dummy.avatar = StringIO.new(".")
+    end
+
+    should "return a url based on an S3 subdomain" do
+      assert_match %r{^http://bucket.s3.amazonaws.com/avatars/stringio.txt}, @dummy.avatar.url
+    end
+  end
+  context "" do
+    setup do
+      rebuild_model :storage => :s3,
+                    :s3_credentials => {
+                      :production   => { :bucket => "prod_bucket" },
+                      :development  => { :bucket => "dev_bucket" }
+                    },
+                    :s3_host_alias => "something.something.com",
+                    :path => ":attachment/:basename.:extension",
+                    :url => ":s3_alias_url"
+      @dummy = Dummy.new
+      @dummy.avatar = StringIO.new(".")
+    end
+
+    should "return a url based on the host_alias" do
+      assert_match %r{^http://something.something.com/avatars/stringio.txt}, @dummy.avatar.url
+    end
+  end
+
   context "Parsing S3 credentials with a bucket in them" do
     setup do
       rebuild_model :storage => :s3,