Here at FastRuby.io we always try to have our own applications in such a state that they can always be pointed to as models in terms of performance and accessibility.

One of the tools we use to achieve that is our CDN. After all, considering we have clients everywhere from the US to New Zealand, we want anyone perusing our websites to have good loading times for the pages and, especially, the assets.

However, no matter how thorough, one always misses a spot or two.

In case you are not familiar with us, FastRuby.io specializes in Ruby and Rails upgrades. Over these past 10 years we have had the opportunity to perform dozens of upgrades for our clients, which has given us all sorts of experiences. A common scenario that we experience is when the upgrade isn’t straightforward and we can’t just upgrade the Ruby or the Rails version directly.

We often find ourselves in a situation where we need to upgrade one or more dependencies before we can actually upgrade Ruby or Rails itself. For instance, if your want to upgrade your app from Rails 5.x to 6.x and the application still uses Paperclip to manage your file attachments, first you’ll need to replace that gem because Paperclip was deprecated in favor of Active Storage after Rails 5.2 was released.

This was the case for one of our clients that has been doing upgrades with us for a few years now. In this article I’m going to share the mishaps found by the team and the strategy that we adopted to migrate their huge volume of attachments over to Active Storage while still keeping Paperclip active until the migration was finished.