Question

I have a download link in my app from which users should be able to download files which are stored on s3. These files will be publicly accessible on urls which look something like

https://s3.amazonaws.com/:bucket_name/:path/:to/:file.png

The download link hits an action in my controller:

class AttachmentsController < ApplicationController
  def show
    @attachment = Attachment.find(params[:id])
    send_file(@attachment.file.url, disposition: 'attachment')
  end
end

But I get the following error when I try to download a file:

ActionController::MissingFile in AttachmentsController#show

Cannot read file https://s3.amazonaws.com/:bucket_name/:path/:to/:file.png
Rails.root: /Users/user/dev/rails/print

Application Trace | Framework Trace | Full Trace
app/controllers/attachments_controller.rb:9:in `show'

The file definitely exists and is publicly accessible at the url in the error message.

How do I allow users to download S3 files?

Answer 1

In order to send a file from your web server,

• you need to download it from S3 (see @nzajt’s answer) or

• you can redirect_to @attachment.file.expiring_url(10)