Enable Subresource Integrity

lib/webpacker/sri_helper_extensions.rb

@@ -0,0 +1,27 @@
+# frozen_string_literal: true
+
+module Webpacker::SriHelperExtensions
+  def stylesheet_link_tag(*sources, **options)
+    tags = sources.map do |stylesheet|
+      if stylesheet.is_a?(Hash)
+        super(stylesheet[:src], options.merge(integrity: stylesheet[:integrity]))
+      else
+        super(stylesheet, options)
+      end
+    end
+    safe_join(tags)
+  end
+
+  def javascript_include_tag(*sources, **options)
+    tags = sources.map do |javascript|
+      if javascript.is_a?(Hash)
+        super(javascript[:src], options.merge(integrity: javascript[:integrity]))
+      else
+        super(javascript, options)
+      end
+    end
+    safe_join(tags)
+  end
+end
+
+Sprockets::Rails::Helper.prepend(Webpacker::SriHelperExtensions)

lib/webpacker/sri_manifest_extensions.rb

@@ -0,0 +1,29 @@
+# frozen_string_literal: true
+
+module Webpacker::SriManifestExtensions
+  def lookup(name, pack_type = {})
+    asset = super
+
+    augment_with_integrity asset, pack_type
+  end
+
+  def lookup_pack_with_chunks(name, pack_type = {})
+    assets = super
+
+    assets.map do |asset|
+      augment_with_integrity asset, pack_type
+    end
+  end
+
+  def augment_with_integrity(asset, _pack_type = {})
+    if asset.respond_to?(:dig) && asset['integrity']
+      {src: asset['src'], integrity: asset['integrity']}
+    elsif asset.respond_to?(:dig)
+      asset['src']
+    else
+      asset
+    end
+  end
+end
+
+Webpacker::Manifest.prepend(Webpacker::SriManifestExtensions)