Using send_file to download a file from Amazon S3?

Keep Things Simple For The User

I think the best way to handle this is using an expiring S3 url. The other methods have the following issues:

• The file downloads to the server first and then to the user.
• Using send_data doesn't produce the expected "browser download".
• Ties up the Ruby process.
• Requires an additional download controller action.

My implementation looks like this:

In your attachment.rb

def download_url
  S3 = AWS::S3.new.buckets[ 'bucket_name' ] # This can be done elsewhere as well,
                                            # e.g config/environments/development.rb
  url_options = { 
    expires_in:                   60.minutes, 
    use_ssl:                      true, 
    response_content_disposition: "attachment; filename=\"#{attachment_file_name}\""
  }

  S3.objects[ self.path ].url_for( :read, url_options ).to_s
end

In your views

<%= link_to 'Download Avicii by Avicii', attachment.download_url %>

That's it.

---

If you still wanted to keep your download action for some reason then just use this:

In your attachments_controller.rb

def download
  redirect_to @attachment.download_url
end

Thanks to guilleva for his guidance.

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)

You can also use send_data.

I like this option because you have better control. You are not sending users to s3, which might be confusing to some users.

I would just add a download method to the AttachmentsController

def download
  data = open("https://s3.amazonaws.com/PATTH TO YOUR FILE") 
  send_data data.read, filename: "NAME YOU WANT.pdf", type: "application/pdf", disposition: 'inline', stream: 'true', buffer_size: '4096' 
end 

and add the route

get "attachments/download"