CDN in Active Storage

The purpose of a CDN is to deliver content faster to users, how? Decreasing the latency of a request using servers that are closer to the user. Imagine that YouTube is a Japanese company and they have all their servers there. For someone from Spain, the user experience would be incredible slow! This means: users get annoyed = conversions drop = loss money

Let’s see how to pass all our uploaded files from Active Storage through a CDN.

Inside our config/routes.rb we have to add an URL helper, also called direct:

direct :cdn do |blob|
  if Rails.env.development? || Rails.env.test?
    route = blob.is_a?(ActiveStorage::Variant) ? :rails_representation : :rails_blob
    route_for(route, blob)
  else
    File.join(Rails.application.credentials.cloudfront_url, blob.key)
  end
end

To use it you can pass the new route to any Active Storage object:

<%= image_tag cdn_url(@user.avatar) if @user.avatar.attached? %>