Set up assets for S3/CloudFront CDN

lib/asset_url.rb

@@ -0,0 +1,22 @@
+module Nanoc3::Helpers::AssetURL
+  def asset_url(path, options = {})
+    name, extension = path.match(/([^.]+).(.+)$/).to_a[1..-1]
+    extensions = extension.split('.')
+
+    asset_dir = options[:asset_dir] || extensions.first
+
+    filename = "content/assets/#{asset_dir}/#{name}.#{extension}"
+    fp = fingerprint(filename)
+
+    path = "/assets/#{asset_dir}/#{name}#{fp}.#{extensions[0..extensions.size-2].join('.')}"
+    if ENV['USE_CDN']
+      @site.config[:cdn_url] + path
+    else
+      path
+    end
+  end
+
+  def image_url(path)
+    asset_url(path, :asset_dir => 'images')
+  end
+end

lib/default.rb

@@ -8,5 +8,6 @@ include Nanoc3::Helpers::Blogging
 include Nanoc3::Helpers::Filtering
 include Nanoc3::Helpers::LinkTo
 include Nanoc3::Helpers::CacheBusting
+include Nanoc3::Helpers::AssetURL
 
 Slim::Engine.set_default_options pretty: true