1 files changed, 26 insertions, 0 deletions
diff --git a/activestorage/app/controllers/active_storage/variants_controller.rb b/activestorage/app/controllers/active_storage/variants_controller.rb
new file mode 100644
index 0000000000..994c57aafd
--- /dev/null
+++ b/activestorage/app/controllers/active_storage/variants_controller.rb
@@ -0,0 +1,26 @@
+# Take a signed permanent reference for a variant and turn it into an expiring service URL for download.
+# Note: These URLs are publicly accessible. If you need to enforce access protection beyond the
+# security-through-obscurity factor of the signed blob and variation reference, you'll need to implement your own
+# authenticated redirection controller.
+class ActiveStorage::VariantsController < ActionController::Base
+  def show
+    if blob = find_signed_blob
+      redirect_to ActiveStorage::Variant.new(blob, decoded_variation).processed.service_url(disposition: disposition_param)
+    else
+      head :not_found
+    end
+  end
+
+  private
+    def find_signed_blob
+      ActiveStorage::Blob.find_signed(params[:signed_blob_id])
+    end
+
+    def decoded_variation
+      ActiveStorage::Variation.decode(params[:variation_key])
+    end
+
+    def disposition_param
+      params[:disposition].presence_in(%w( inline attachment )) || "inline"
+    end
+end