Crypto Smart Camera: Pre-signed POST to S3

request_signing.rb

module RequestSigning
  extend ActiveSupport::Concern

  included do
    before_action :set_s3_direct_post, only: [:new]
  end

  def set_s3_direct_post
    @s3_direct_post = AWS_S3_BUCKET.presigned_post(key: "uploads/#{SecureRandom.uuid}/${filename}", success_action_status: '201', acl: 'public-read')
  end
end

This concern provides a callback which can be used in a controller to populate a form for direct S3 file uploads

    <%= form_for(note, html: {
        class: 'direct-upload',
        data: {
          'form-data' => (@s3_direct_post.fields),
          'url' => @s3_direct_post.url,
          'host' => URI.parse(@s3_direct_post.url).host
          }
        }) do |note_form| %>