Using send_file to download a file from Amazon S3?

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

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"