Storage backend for Paperclip to help migrate from the filesystem to S3 with fog.
Failed to load latest commit information.


Build Status

paperclip-multiple is a storage implementation for Paperclip. It aims to help migrating files from filesystem storage to fog storage.

It provides the multiple storage which instantiates two Attachments, one using filesystem storage and another using fog storage. From the moment the multiple storage is enabled, new files will be stored on both locations while still displaying the files from the filesystem.

While paperclip-multiple helps you store files in two places, you will also want to sync existing files. We used s3cmd and s3cmd sync to do this.

paperclip-multiple was prepared to migrate to S3. It was not prepared to:

  • Migrate from S3 to filesystem.
  • Migrate to use the S3 backend instead of the fog.

Paperclip was not prepared to have multiple backends, so this little thing messes with some of the internals of Paperclip.

⚠️ ⚠️ Warning ⚠️ ⚠️

The nature of this software means that once we finished the migration, we aren't using it anymore.

It also messes with the internals of Paperclip, meaning it will possibly break in future releases. We are not going to actively maintain this library, but we wanted to offer this code to everyone that might find a use for it. We struggled to find any useful code in this regard, and even an old version of what you see here, paperclip-multiple, would have been appreciated.

Feel free to ask questions or fork this code. For the reasons stated before, we might not be able to provide with very good support. However, if there's something very obvious or broken and want to contribute with a nice Pull Request, we'll do our best.


Add paperclip-multiple to your Gemfile.

gem 'paperclip-multiple', github: 'harvesthq/paperclip-multiple'

Make sure you have valid settings for both the filesystem and the fog storages. Let's suppose you have information available in a constant like this:

  fog_credentials: {
    aws_access_key_id: "whatever",
    aws_secret_access_key: "whatever",
    provider: "AWS"
  fog_public:    true,
  fog_directory: "bucket-name"

Use it in your has_attached_file definition:

class User
  has_attached_file :file, PAPERCLIP_SETTINGS.merge(
    storage: :multiple,
    path: ":compatible_rails_root/users/files/:user_id/:style.:extension",
    url:  "/uploads/users/files/:user_id/:style.:extension",
    multiple_if:     lambda { |user|      },
    display_from_s3: lambda { |user| }

Three things might surprise you, let me explain them:

What's that thing in your path?

You must not forget that Paperclip will be used for both fog and filesystem. If your path option contained some absolute path, you'll have to tweak it to make it work with both storages.

This is what our :compatible_rails_root interpolation looks like:

Paperclip.interpolates(:compatible_rails_root) do |attachment, _|
  if attachment.options[:storage] == :fog
    "#{rails_root(attachment, _)}/public/uploads"

Be sure to test this in some staging environment. It's not trivial to get the slashes right!


At Harvest we like to rollout things in slow, metered releases. The multiple_if option allows you to define when an instance will indeed start using the multiple attachment. If this block returns false, then it will work as if the filesystem backend was used.


This is the counterpart to the previous option. Multiple storage mainly delegates around to the real Attachment. When you call url on your attachment, the multiple storage simply calls the Attachment with the filesystem storage configured. If this block returns true, it will call url on the Attachment with fog storage. A totally random example: # => false
user.file.url # => '/uploads/users/files/1234/original.jpg' # => true
user.file.url # => ''


@mrsimo built this to solve one of the multiple problems we face every day at Harvest. We're quite definitely hiring!