Welcome to our series of Rails upgrade miniguides. Here you'll find links to all of the relevant posts to help with an upgrade.

Sometimes you will be caught between a rock and a hard place. For example: You really need to upgrade your Rails application because Heroku is discontinuing your stack in two weeks so you don't have the time to write an entire test suite.

Sometimes the situation will be that your boss really needs you to upgrade Ruby or Rails to use a version that gets security updates and they won't allow you to write tests beforehand.

This article will explain how to ship a Rails upgrade project without a test suite. If your application has no tests, you will learn how to upgrade without having to write tests first.

This article is part of our Upgrade Rails series. To see more of them, click here.

This article will cover the most important aspects that you need to know to prepare your Ruby on Rails application for working on an upgrade.

If you’re a developer you know the reasons why you should be using the latest Rails framework. You understand the implications of performance gains, dependency issues and unsupported versions.

But these big picture benefits get lost in translation when talking to non-technical executives. What they need to know is the business case for an upgrade, how the work will translate into increased revenue.

So, here is an article to use or forward to communicate why an upgrade should be a priority. We also wrote an article on the more technical reasons if you are interested.

Ruby 3x3 is coming in about a month. One of its new concurrency primitives is Ractors, which used to be called "Guilds." (The other new concurrency primitive is Autofibers.)

Ruby has a Global VM Lock (GVL), also called the Global Interpreter Lock (GIL), that prevents running Ruby code in more than one thread at once. So Ruby threads are great for I/O like waiting on files or databases. And they're great for cases where a C extension can keep calculating in a background thread while a foreground thread runs Ruby. But you can't do calculations in Ruby in more than one thread at once within the same process.

At least not until Ruby 3 and not without Ractors.

Great! Now how fast is the current implementation of Ractors?

When upgrading a Rails application, you might find that sometimes functionality is extracted from Rails and moved into a new gem. These gems are called shims, and they will basically allow you to keep using an old functionality, once the core API takes that out. You can also find shims in form of monkey patches. In this case it's functionality that you develop to make your migration easier.

In this article I will list some of the functionality of past versions of Rails that was extracted into gems.

Back in 2011, Rails 3.1 introduced The Assets Pipeline feature using the Sprockets gem. This made it really easy to handle assets (images, fonts, JavaScript, CSS and more), solving many of the issues that developers had to face everyday.

In 2012, Webpack was released solving the same issues in a different way and in time became the most used solution to handle assets. And since Rails 6, Webpack became the default solution to handle JavaScript assets using the Webpacker gem on new Rails applications.

In this article I'll explain the steps we took to migrate to Webpack to handle our JavaScript assets, and how we added support as a node module in our styleguide.

Do you ever look at the list of Amazon EC2 instance types?. Those are sizes of virtual machine you can rent to run your code on. Well, okay, they're groups of sizes, since each one of those headings has a bunch of different sizes of VM...

So what type of EC2 instances should you run your Rails app on?

The answer is simpler than it looks.

Do you love numbers? I love numbers. Do you hate numbers? Skip to the bottom, there's a nice summary paragraph. Do you really really love numbers? There are raw data dumps including all my intermediate results.

When inheriting a project or starting an upgrade, it is useful to understand how big and complex the application really is. So, what is a good way to understand whether a Rails application is tiny, medium, or huge?

The good news is that there are a couple of gems that make this easy for us.

In this article I will explain how you can use these gems to begin to understand the size and complexity of a Rails application.

The new Ruby 3.0 preview is out! Woo-hoo!

If you've heard of me, you know performance is kinda my thing, especially Rails performance on large apps. I do other stuff too, but I got paid to do that for years (thanks, AppFolio!), so I've written a lot about it.

How does the new preview's performance stack up on Rails? And how reliable are these numbers?

At FastRuby.io we are constantly looking at code coverage metrics for Ruby on Rails applications. It's a key indicator for us. We even use that information to decide whether we work on a Rails upgrade project or not.

So, I was interested in seeing code coverage metrics for the Ruby on Rails framework. I couldn't find any information about this online, so I decided to generate a few reports for each component.

This is an article about my process and my findings.

Having a clear idea of how much test coverage your Rails application has is really important. Especially if you are planning to upgrade to a newer version of Rails. A good test suite will tell you if your application is working as it did before the upgrade.

At FastRuby.io, we recommend having at least 80% of your application covered before attempting to upgrade. A number lower than that would require you to make a lot more manual testing to ensure that the application is properly working after the upgrade. If your application doesn't meet that number, we suggest to first spend some time improving the test suite before starting the upgrade.

In this article, I'll show you how you can measure your test coverage using SimpleCov.

A quick note before starting: SimpleCov doesn't work in projects with Ruby 1.8.7 or lower. If that's your case, you can try rcov.

Contributing to open source projects is a big part of our philosophy at OmbuLabs. It’s even written into our values. Some of us like to contribute to open source even in our spare time!

Recently we have been thinking about what guidelines we should follow when starting a new open source project, and also about how to organize and keep track of the ones we contribute to.

This article will give you some tips on keeping those open source projects organized, and also how to start them off on the right foot.

We recently collaborated with Procore on a Rails upgrade for their Rails application which allows teams in the construction industry to connect their entire business process.

We spoke with Andy Maltun, Procore’s VP of Software Engineering, about the work performed to help them upgrade their app to version 5.1. According to Maltun, Procore’s R&D department is large and complex. While Procore previously had handled their Rails upgrades internally, with so many teams working on the application, it caused a lot of disruption as each team would handle only part of the upgrade. Therefore, Maltun "wanted to take a different approach this time in an effort to centralize the update and minimize the project management overhead and disruption of teams."

Rails upgrades can be done in many different ways. Depending on the application that you want to upgrade, some ways make more sense than others. There are factors that determine which Rails upgrade strategy is the best for your case, like how big your application is, or how frequently changes are pushed to the master branch. In this article I'll be covering two common Rails Upgrade strategies so you can decide which one is the best for your application.