Sidekiq + Carrierwave + S3 (Image upload in background)

Question

I want to upload a user's profile picture in the background since the picture can be large. I am going to use Carrierwave + Fog (Amazon S3) + Sidekiq for this.

I can implement it without Sidekiq first:

users_controller.rb

def update
  @user = User.find(params[:id])
  if params[:profile_picture]
    // params[:profile_picture] has ActionDispatch::Http::UploadedFile type
    @user.profile_image = params[:profile_picture]
  end

  ...
end

models/user.rb

mount_uploader :profile_picture, ProfilePictureUploader

It works perfectly without any hassle. Now, I want to offload this job to a sidekiq worker.

users_controller.rb

def update
  @user = User.find(params[:id])
  if params[:profile_picture]
    // Below path is in this kind of form:
    // /var/folders/ps/l8lvygws0w93trqz7yj1t5sr0000gn/T/RackMultipart20161110-46798-w9bgb9.jpg
    @user.profile_image = params[:profile_picture].path
  end

  ...
end

profile_picture_upload_job.rb

class ProfilePictureUploadJob
  include Sidekiq::Worker

  def perform(user_id, image_path)
    user = User.find(user_id)
    // HELP: I don't know what to do here!
    user.remote_profile_picture_url = image_path
    // user.profile_picture = image_path
    user.save!
  end
end

Since you can't pass a binary file to Redis, I thought I'd have to pass the path of the temporarily uploaded file. But I can't find a way to actually upload it with Sidekiq.

I think this can be solved by using Carrierwave_Backgrounder gem. But I wanted to try to understand how to do it without using the gem.

Answer 1

The solution is to pass the path to the temporary file to SideKiq's worker, and opening it before uploading it via Carrierwave.

users_controller.rb

def update
  @user = User.find(params[:id])
  if params[:profile_picture]
    // Below path is in this kind of form:
    // /var/folders/ps/l8lvygws0w93trqz7yj1t5sr0000gn/T/RackMultipart20161110-46798-w9bgb9.jpg
    @user.profile_image = params[:profile_picture].path
  end

  ...
end

profile_picture_upload_job.rb

class ProfilePictureUploadJob
  include Sidekiq::Worker

  def perform(user_id, image_path)
    user = User.find(user_id)
    user.profile_picture = File.open(image_path)
    user.save!
  end
end

UPDATE:

But this solution doesn't work on Heroku:

2016-11-11T11:34:06.839408+00:00 app[worker.1]: 4 TID-osgdwad5o WARN: Errno::ENOENT: No such file or directory @ rb_sysopen - /tmp/RackMultipart20161111-4-1poz958.jpg