RailsConf 2022 - Upgrading Rails: The Dual Boot Way

#RailsUpgrades | https://fastruby.io/rc2022 Upgrading Rails The Dual Boot Way RailsConf 2022 Hello RailsConf 2022!

#RailsUpgrades | https://fastruby.io/rc2022 Mike Toppa (he/him) I have two co-presenters with me today. We’ll each introduce ourselves, and we can start with me.   My name is … My pronouns are …

#RailsUpgrades | https://fastruby.io/rc2022 Senior Engineering Manager at FastRuby.io I’m a Senior Engineering Manager at FastRuby.io. Over the past 25 years I’ve worked in various roles - from Developer, to Product Owner, to Director - for ActBlue, The University of Pennsylvania, Stanford University, Ask Jeeves, E*Trade, and others. I’m passionate about helping teams improve and I've led several Agile transitions. And I’ve been working with Rails for the past 10 years.

#RailsUpgrades | https://fastruby.io/rc2022 @mtoppa You can follow me on Twitter

#RailsUpgrades | https://fastruby.io/rc2022 Ernesto Tagwerker 🇦🇷 (he/him) My name is … My pronouns are …

#RailsUpgrades | https://fastruby.io/rc2022 @etagwerker You can fi nd me on Twitter.

#RailsUpgrades | https://fastruby.io/rc2022 Founder & CTO at OmbuLabs I’m the founder and CTO at OmbuLabs Small consultancy based in Philadelphia

#RailsUpgrades | https://fastruby.io/rc2022 Founder & CTO at FastRuby.io A few years ago we decided to launch a “productized service” specialized in Ruby on Rails upgrades.

#RailsUpgrades | https://fastruby.io/rc2022 Luciano Becerra 🇦🇷 (he/him) Hi everyone, my name is Luciano Becerra I’m from Buenos Aires, Argentina My pronouns are he/him

#RailsUpgrades | https://fastruby.io/rc2022 Senior Software Engineer at FastRuby.io I’m a Senior Software Engineer at FastRuby and OmbuLabs. I’ve been in the company for about 6 years.

#RailsUpgrades | https://fastruby.io/rc2022 @lubc32 And you can fi nd me on Twitter with this handle

#RailsUpgrades | https://fastruby.io/rc2022 🐦 #RailsUpgrades 🐦 If you want to tweet about this workshop, use the hashtag #RailsUpgrades. We’re always looking for feedback on our process and ways to improve this workshop.

#RailsUpgrades | https://fastruby.io/rc2022 Why do we need this workshop? This workshop is for anyone who needs to upgrade a Rails application. At FastRuby.io, we have performed over 80 Rails upgrades, and have fi xed thousands of old dependencies and evaluated countless migrations. Today we’ll be sharing with you some of the strategies we’ve developed over the years to perform Rails upgrades ef fi ciently and reliably. If you are in this workshop, it would serve you best if you have your computer and an outdated Rails application in front of you. If you don’t have a Rails app, feel free to stay and take notes. I have a list of outdated, open source, Rails applications, for you to use during the workshop.

#RailsUpgrades | https://fastruby.io/rc2022 `bundle update` should be easy But can’t you just run bundle update? Maybe, but often it’s not enough. We often have large, complex applications with a multitude of dependencies, and bundle update can’t address every issue.

#RailsUpgrades | https://fastruby.io/rc2022 bundle update rails ? So often what happens is you try to run bundle update, and you spend days or weeks trying to sort out problems that come up. Then your company needs you to start delivering features again, and you decide to put off the upgrade to another day. And then that day never comes, because there are too many other things you have to do. Then you end up running an old version of Rails in production, which poses security risks and imposes limitations on your development, as you are tied to old gems and old ways of doing things.

#RailsUpgrades | https://fastruby.io/rc2022 Ruby For Good: Refuge Restrooms In this workshop we’re going to show you a gradual, step-by-step way to upgrade. And the best way to do that is to work with a real life application. We’re going to upgrade an application from Ruby For Good called Refuge Restrooms. It’s an open source application that indexes and maps safe restroom locations for trans, intersex, and gender nonconforming individuals. It’s currently on Rails 5.2 and we’re going to upgrade it to 6.0.

#RailsUpgrades | https://fastruby.io/rc2022 Workshop Outline So, how are we going to do it? Let’s start with a quick overview of what we’re going to cover today. We’ll go over 7 different steps that we take to create a roadmap and start an upgrade.

#RailsUpgrades| https://fastruby.io/rc2022 7 Exercises: 1. Prerequisites: Docker and Git Refuge Restrooms is con fi gured to use Docker. So we’ll make sure you have git, docker, and other prerequisites set up on your computer if you don’t have them already.

#RailsUpgrades| https://fastruby.io/rc2022 7 Exercises: 1. Prerequisites: Docker and Git 2. Setup with docker-compose You’ll need to clone the GitHub repository for Refuge Restrooms, and start it up in Docker

#RailsUpgrades| https://fastruby.io/rc2022 7 Exercises: 1. Prerequisites: Docker and Git 2. Setup with docker-compose 3. Introduction to next_rails Then we will set up the `next_rails` gem. It’s a gem we maintain at FastRuby.io, and it will prove useful for all your future rails upgrades. It will help with things like dual booting and fi nding incompatibilities with future versions of Rails.

#RailsUpgrades| https://fastruby.io/rc2022 7 Exercises: 1. Prerequisites: Docker and Git 2. Setup with docker-compose 3. Introduction to next_rails 4. Start the dual boot setup Then we are going to start the set up for Refuge Restrooms to boot with two different versions of Rails. The current 5.2 version, and 6.0, which is the version we want to upgrade to.

#RailsUpgrades| https://fastruby.io/rc2022 7 Exercises: 1. Prerequisites: Docker and Git 2. Setup with docker-compose 3. Introduction to next_rails 4. Start the dual boot setup 5. Finish the dual boot setup The next_rails gem lets us try running bundle update with the next version of Rails, without disturbing the current version. When we try it, we’ll run into an issue in Refuge Restrooms that needs to be fi xed, and we’ll work with you to resolve it.

#RailsUpgrades| https://fastruby.io/rc2022 7 Exercises: 1. Prerequisites: Docker and Git 2. Setup with docker-compose 3. Introduction to next_rails 4. Start the dual boot setup 5. Finish the dual boot setup 6. Run the Rails console & run the tests We’ll open the Rails console in each version of Rails, to con fi rm the dual boot is working. Then we’ll run the tests in both versions. We’ll see a deprecation warning for Rails 6.

#RailsUpgrades| https://fastruby.io/rc2022 7 Exercises: 1. Prerequisites: Docker and Git 2. Setup with docker-compose 3. Introduction to next_rails 4. Start the dual boot setup 5. Finish the dual boot setup 6. Run the Rails console & run the tests 7. Find and fi x a class autoloading issue Lastly, we’ll try to upgrade to the new class autoloader in Rails 6, and we’ll encounter an error, and fi x it.

#RailsUpgrades| https://fastruby.io/rc2022 fastruby.io/ rc2022 There’s a companion page for this workshop at fastruby.io/rc2022 which describes all the steps. You’ll see the link for it the footer of every slide, so it’s easy for you to fi nd at anytime during the workshop. If you bookmark it, you can also refer to it later.

#RailsUpgrades| https://fastruby.io/rc2022 Steps: 1. Explanation 2. Questions 3. Exercise time For each step in the upgrade process, we’ll provide an explanation for why we want to do it, how we’ll do it, and what you should expect to see. Then we’ll answer any questions, and after that you can do the step yourself. There will be 5 to 15 minutes for each exercise, and we’ll be here to help you individually if you get stuck or have any problems completing the step.

#RailsUpgrades | https://fastruby.io/rc2022 Prerequisites Let’s start with the prerequisites. What you will need to work on this workshop.

#RailsUpgrades| https://fastruby.io/rc2022 Pre-requisites: ✓ Docker ✓ Docker-Compose ✓ Git We will be using Docker; docker-compose; and Git.

#RailsUpgrades| https://fastruby.io/rc2022 $ git —-version > git version 2.30.1 (Apple Git-130)

#RailsUpgrades| https://fastruby.io/rc2022 $ docker-compose --version > docker-compose version 1.29.2, build 5becea4c

#RailsUpgrades| https://fastruby.io/rc2022 $ docker --version > Docker version 20.10.8, build 3967b7d

#RailsUpgrades| https://fastruby.io/rc2022 Questions? Do you have any questions about the pre-requisites?

#RailsUpgrades| https://fastruby.io/rc2022 Exercise #1: Check Prerequisites Time: 5 to 10 minutes https://fastruby.io/rc2022#1 Now go do it and let me know if you have any problems.

#RailsUpgrades | https://fastruby.io/rc2022 Docker setup Once we checked all the pre-requisites, we can start setting up the sample application with Docker TODO: Explain a bit about Docker and why we’re using it here

#RailsUpgrades| https://fastruby.io/rc2022 $ git clone https://github.com/fastruby/refugerestrooms $ cd refugerestrooms $ git checkout start-exercise-1 To do that, fi rst clone the refuge restrooms repo from Github And once it fi nished downloading, go to that folder

#RailsUpgrades| https://fastruby.io/rc2022 If you are on a Mac with an M1 chip, you will need to run: $ docker-compose -f docker-compose.yml -f docker-compose.mac-m1.yml up --no-build   Then Ctrl-C when it's done. And run: $ docker-compose -f docker-compose.yml -f docker-compose.mac-m1.yml run web /bin/bash /About This Mac If you are on a Mac with an M1 chip, you will need to run these commands

#RailsUpgrades| https://fastruby.io/rc2022 If you are NOT on a Mac with an M1 chip: $ docker-compose run web bash To setup the Docker image you can run this command This will take a few minutes to run, depending on the WI-FI connection. Last time I tried it took me around 7 minutes

#RailsUpgrades| https://fastruby.io/rc2022 $ docker-compose run web bash Once it fi nishes running, your terminal will look something like this. Now you’ll be able to run any command and it’ll run it inside Docker

#RailsUpgrades| https://fastruby.io/rc2022 Exercise #2: Time: 10 to 15 minutes 1) Clone the repository (fastruby/refugerestrooms) 2) Run docker-compose run web bash https://fastruby.io/rc2022#2 So now let's take a few minutes to setup Docker

#RailsUpgrades | https://fastruby.io/rc2022 How outdated is our application? Before we start making changes that will get us closer to the next version of Rails, we want to know how outdated is our application. That way we can have a more clear idea of how far we are from the next version of Rails.

#RailsUpgrades| https://fastruby.io/rc2022 Analyze our Gem fi le With the next_rails gem So, to know that we can analyze our Gem fi le. There are a few ways to do that, but the one that gives the most precise information is by using the `next_rails` gem

#RailsUpgrades| https://fastruby.io/rc2022 next_rails gem This is a gem that we maintain at FastRuby.io and it's a fork of..

#RailsUpgrades| https://fastruby.io/rc2022 ... the ten-years-of-rails gem that was created by Jordan Raine for the talk that he did at Rails Conf 2018.

#RailsUpgrades| https://fastruby.io/rc2022 # Gemfile group :development, :test do gem 'next_rails' end To install this gem you simply add it to your Gem fi le, like this. Keep in mind that you'll need Ruby 2.3 or higher for it to work. Our sample application runs on ruby 2.7 so we’re good

#RailsUpgrades| https://fastruby.io/rc2022 $ bundle Fetching gem metadata from https://rubygems.org/.......... ... Fetching next_rails 1.0.5 Installing next_rails 1.0.5 ... Bundle complete! 50 Gemfile dependencies, 163 gems now installed. And then you run `bundle` in the terminal to install the gem.

#RailsUpgrades| https://fastruby.io/rc2022 1) bundle_report outdated 2) bundle_report compatibility —rails-version=6.0.5 next_rails commands So, now that we have the next_rails gem installed, we are able to run these 2 di ff erent commands:

#RailsUpgrades| https://fastruby.io/rc2022 1) bundle_report outdated 2) bundle_report compatibility —rails-version=6.0.5 next_rails commands The 1st one is `bundle_report outdated`, which outputs all your gems from oldest to newest with speci fi c release details on each of the gems.

#RailsUpgrades| https://fastruby.io/rc2022 $ bundle_report outdated puma 5.6.2: released Jan 1, 1980 (latest version, 5.6.4, released Jan 1, 1980) formtastic_i18n 0.6.0: released Mar 10, 2016 (latest version, 0.7.0, released May 23, 2021) … rails 5.2.6.3: released Mar 8, 2022 (latest version, 7.0.3, released May 9, 2022) bundler 2.1.4: released Mar 29, 2022 (latest version, 2.3.13, released May 4, 2022) 0 gems are sourced from git 105 of the 163 gems are out-of-date (64%) It looks like this when you run it. As you can see, for each gem it shows:

#RailsUpgrades| https://fastruby.io/rc2022 $ bundle_report outdated redcarpet 3.0.0: released over 5 years ago (latest version, 3.4.0, released over 2 years ago) bootstrap-sass 3.3.7: released over 2 years ago (latest version, 3.4.1, released about 2 months ago) ... mail 2.7.0: released over 1 year ago (latest version, 2.7.1, released 6 months ago) activesupport 5.1.6: released about 1 year ago (latest version, 5.2.3, released 11 days ago) railties 5.1.6: released about 1 year ago (latest version, 5.2.3, released 11 days ago) 0 gems are sourced from git 65 of the 102 gems are out-of-date (64%) - When was it released

#RailsUpgrades| https://fastruby.io/rc2022 $ bundle_report outdated redcarpet 3.0.0: released over 5 years ago (latest version, 3.4.0, released over 2 years ago) bootstrap-sass 3.3.7: released over 2 years ago (latest version, 3.4.1, released about 2 months ago) ... mail 2.7.0: released over 1 year ago (latest version, 2.7.1, released 6 months ago) activesupport 5.1.6: released about 1 year ago (latest version, 5.2.3, released 11 days ago) railties 5.1.6: released about 1 year ago (latest version, 5.2.3, released 11 days ago) 0 gems are sourced from git 65 of the 102 gems are out-of-date (64%) - What's the latest version

#RailsUpgrades| https://fastruby.io/rc2022 $ bundle_report outdated redcarpet 3.0.0: released over 5 years ago (latest version, 3.4.0, released over 2 years ago) bootstrap-sass 3.3.7: released over 2 years ago (latest version, 3.4.1, released about 2 months ago) ... mail 2.7.0: released over 1 year ago (latest version, 2.7.1, released 6 months ago) activesupport 5.1.6: released about 1 year ago (latest version, 5.2.3, released 11 days ago) railties 5.1.6: released about 1 year ago (latest version, 5.2.3, released 11 days ago) 0 gems are sourced from git 65 of the 102 gems are out-of-date (64%) - And how old is that version

#RailsUpgrades| https://fastruby.io/rc2022 1) bundle_report outdated 2) bundle_report compatibility —-rails-version=6.0.5 next_rails commands And the 2nd command is `bundle_report compatibility`, which will tell you what are the gems that won't work with the version of rails that you want to upgrade to. In this example it's Rails 6.0.5

#RailsUpgrades| https://fastruby.io/rc2022 $ bundle_report compatibility --rails-version=6.0.5 => Incompatible with Rails 6.0.5 (with new versions that are compatible): These gems will need to be upgraded before upgrading to Rails 6.0.5. dotenv-rails 2.2.2 - upgrade to 2.7.6 1 gems incompatible with Rails 6.0.5 It looks like this when you run it. The output shows what gems will not work with that rails version, but have a version that works And it can also show what gems will not work and don't have a newer version of that gem that is compatible. But this speci fi c project doesn’t have any gem like that so it’s not showing this section in the output

#RailsUpgrades| https://fastruby.io/rc2022 Exercise #3: Time: 5 to 10 minutes 1) Install next_rails gem 2) Run bundle_report outdated 3) Run bundle_report compatibility —-rails-version=6.0.5 https://fastruby.io/rc2022#3 So now let's take a few minutes to install next_rails, and run these two commands in your application Also you can go to the link on screen to see the things I just shared in the slides

#RailsUpgrades | https://fastruby.io/rc2022 Dual Boot: Setup The next step toward upgrading your Rails application is setting up Dual Booting. This allows you to run your application with two di ff erent versions of Rails. The one that you currently have, and the want you want to upgrade to. The main bene fi t of this is that you can easily see what parts of your code won't work with the next version of Rails and need to be updated. The next_rails gem has a command for doing this setup

#RailsUpgrades| https://fastruby.io/rc2022 $ next --init You can run `next --init`. This will do 2 things:

#RailsUpgrades| https://fastruby.io/rc2022 $ next --init Gem fi le Gem fi le.next The fi rst one is that creates a symlink of our Gem fi le, called Gem fi le.next

#RailsUpgrades| https://fastruby.io/rc2022 Gem fi le Gem fi le.next Gem fi le.lock Gem fi le.next.lock bundle install next bundle install This is necessary so we can have 2 separate Gem fi le locks, one for when we run `bundle install` and one for when we run `next bundle install`, which I'll show you in a moment

#RailsUpgrades| https://fastruby.io/rc2022 # Gemfile def next? File.basename(__FILE__) == "Gemfile.next" end $ next --init And the 2nd thing `next --init` does is that adds this useful method to our Gem fi le that we can use in our code. We'll see how we can use it after the next exercise.

#RailsUpgrades| https://fastruby.io/rc2022 Exercise #4: Time: 5 minutes 1) Run next --init 2) Check that a Gemfile.next was created 3) Check that you have the next? method in your Gemfile https://www.fastruby.io/rc2022#4 So now let's take a few minutes to run `next --init` If for some reason the command does’t work for you. You can add those things manually. That link has instructions on how to do it.

#RailsUpgrades| https://fastruby.io/rc2022 # Gemfile if next? gem 'rails', '~> 6.0.5' else gem 'rails', '5.2.6.3' end Now that we have Dual Boot setup, we can use the new `next?` method that we have.

#RailsUpgrades| https://fastruby.io/rc2022 $ next bundle update rails Now you can try to update the rails gem.

#RailsUpgrades| https://fastruby.io/rc2022 $ next bundle update rails ... Bundler could not find compatible versions for gem "railties": In Gemfile.next: dotenv-rails (~> 2.2.1) was resolved to 2.2.2, which depends on railties (>= 3.2, < 6.0) rails (~> 6.0.5) was resolved to 6.0.5, which depends on railties (= 6.0.5) If you see something like this, means you'll need to add the `next?` conditional to the gems that are con fl icting, which in this case is dotenv-rails

#RailsUpgrades| https://fastruby.io/rc2022 # Gemfile if next? gem 'dotenv-rails' else gem 'dotenv-rails', '~> 2.2.1' end

#RailsUpgrades| https://fastruby.io/rc2022 $ next bundle update rails dotenv-rails

#RailsUpgrades| https://fastruby.io/rc2022 Exercise #5: Time: 5 to 10 minutes 1) Use the `next?` method in the Gemfile 2) Run next bundle update rails dotenv-rails https://www.fastruby.io/rc2022#5 So now let's take a few minutes to run `next bundle install`

#RailsUpgrades | https://fastruby.io/rc2022 Run the Rails console One of the things we can try doing now is to run the rails console with the next version of rails By doing this, we’re are gonna be exercising the initializers and environment fi les, and we’ll be able to see if if they raise any error caused by the version of rails we’re using

#RailsUpgrades| https://fastruby.io/rc2022 68 $ bundle exec rails console Loading development environment (Rails 5.2.6.3) irb(main):001:0> $ next bundle exec rails console Loading development environment (Rails 6.0.5) irb(main):001:0> So here there are the two options to access to the console

#RailsUpgrades| https://fastruby.io/rc2022 69 $ bundle exec rails console Loading development environment (Rails 5.2.6.3) irb(main):001:0> $ next bundle exec rails console Loading development environment (Rails 6.0.5) irb(main):001:0> The fi rst one will run it with your current version of Rails

#RailsUpgrades| https://fastruby.io/rc2022 70 $ bundle exec rails console Loading development environment (Rails 5.2.6.3) irb(main):001:0> $ next bundle exec rails console Loading development environment (Rails 6.0.5) irb(main):001:0> And the other with with the next version of Rails

#RailsUpgrades | https://fastruby.io/rc2022 Run the test suite And now, the next step is to try to run the test suite The process is similar to what we did with the rails console

#RailsUpgrades| https://fastruby.io/rc2022 72 $ bundle exec rspec ......................................................... Finished in 58.22 seconds (files took 2.49 seconds to load) 64 examples, 0 failures We can run the tests with the current version of rails fi rst, which shouldn’t have any failure in the sample application

#RailsUpgrades| https://fastruby.io/rc2022 73 $ next bundle exec rspec DEPRECATION WARNING: Class level methods will no longer inherit scoping from `current` in Rails 6.1. To continue using the scoped relation, pass it into the block directly. To instead access the full set of models, as Rails 6.1 will, use `Restroom.default_scoped`. (called from block in <class:Restroom> at /refugerestrooms/app/models/ restroom.rb:47) ......................................................... Finished in 35.61 seconds (files took 3.04 seconds to load) 64 examples, 0 failures And then we can run them with the next version rails, which in this case, since it’s a small app, with not a lot of tests, it doesn’t have any failures either The only difference in the output is that there’s a deprecation warning, but we don’t have to worry about that yet. That would be need to be addressed once we’re on 6.0 and we’re ready to upgrade to 6.1

#RailsUpgrades| https://fastruby.io/rc2022 Every deprecation warning is a story One thing to note about Deprecation Warnings is that for every unique deprecation warning that you see in your application, should create a story or a ticket in your rails upgrade roadmap. In the bonus section of the companion page we explain how to use a feature that next_rails has to track deprecation warning

#RailsUpgrades| https://fastruby.io/rc2022 Exercise #6 Time 5 to 10 min 1)Run bundle exec rails console 2)Run next bundle exec rails console 3)Run bundle exec rails rspec 4)Run next bundle exec rspec https://www.fastruby.io/rc2022#6 A last thought on the deprecation warnings. We’re not going to fi x them right now. These are deprecation warning that were introduced in Rails 6.0, which means they should be fi xed as part of an upgrade to Rails 6.1

#RailsUpgrades| https://fastruby.io/rc2022 Strategy for fi xing deprecation warnings when doing multiple version jumps in a row For example, going from Rails 5.1 to 6.1:   • 5.1 to 5.2: fi x Rails 5.1 deprecation warnings • 5.2 to 6.0: fi x Rails 5.2 deprecation warnings • 6.0 to 6.1: fi x Rails 6.0 deprecation warnings • Then fi x Rails 6.1 deprecation warnings A fi nal thought on deprecation warnings… This helps you keep organized with how you fi x deprecations warnings, especially if you have not addressed deprecation warnings in your current version of Rails. In the interests of time, we are going to skip fi xing the new Rails 6.0 deprecation warnings we saw, and instead focus on the error that you’ll see in a minute. But on the companion page for this workshop, there’s a bonus section at the end, which explains how to fi x the deprecation warnings.

#RailsUpgrades | https://fastruby.io/rc2022 Dual booting & debugging an error As we move to the next step in the Rails 6 upgrade, we’ll encounter an error that needs to be fi xed. For this part of the workshop, please follow along with me during each slide, instead of waiting for the exercise at the end.

#RailsUpgrades| https://fastruby.io/rc2022 # In config/application.rb: config.load_defaults 6.0 # Try running the test suite again: $ next bundle exec rspec spec/models/

#RailsUpgrades| https://fastruby.io/rc2022 You should see an error, after the deprecation warning An error occurred while loading ./spec/models/ rating_level_spec.rb. Failure/Error: require File.expand_path('../ config/environment', __dir__) NameError: uninitialized constant API Did you mean? Api Why did this happen?

#RailsUpgrades| https://fastruby.io/rc2022 Class autoloading changed in Rails 6

#RailsUpgrades| https://fastruby.io/rc2022 🤔 What is a class autoloader? Ok… what does that mean exactly?

#RailsUpgrades| https://fastruby.io/rc2022 Using Ruby WITHOUT Rails, you have to explicitly load class files before you can use the class # For example, you need to: require 'workers/observation'   # Before you can: Observation = Workers::Observation.new

#RailsUpgrades| https://fastruby.io/rc2022 Rails has always had a class autoloader. It automatically infers how to load classes.

#RailsUpgrades| https://fastruby.io/rc2022 Class autoloading changed in Rails 6. It’s now done with the Zeitwerk gem. There were various issues with the Rails autoloader, which made autoloading a bit tricky and sometimes confusing. Zeitwerk addresses these issues.

#RailsUpgrades| https://fastruby.io/rc2022 Some of the changes with Zeitwerk are not backwards compatible Zeitwerk was designed to be as compatible as possible with the classic autoloader. But there are some incompatibilities, and we’ll encounter one in this project.

#RailsUpgrades| https://fastruby.io/rc2022 Let’s get the tests to pass with the “classic” autoloader   # In config/application.rb, add: config.autoloader = :classic # The tests should pass again now: $ next bundle exec rspec spec/models/ The original Rails autoloader is now called the “classic” autoloader. Let’s temporarily switch to using it with Rails 6.

#RailsUpgrades| https://fastruby.io/rc2022 87 Now let’s update the app for Zeitwerk!   # In config/application.rb, change: config.autoloader = :zeitwerk # Then run: $ next bin/rails zeitwerk:check # You should see an error that’s similar # to the one we saw in the tests

#RailsUpgrades| https://fastruby.io/rc2022 How do we fix it? See the Acronyms section of Classic to Zeitwerk HOWTO # In config/initializers/inflections.rb add: ActiveSupport::Inflector.inflections(:en) do |inflect| inflect.acronym "API" end # The check should pass now: $ next bin/rails zeitwerk:check # And the tests should pass again now: $ next bundle exec rspec spec/models/ Say more about how acronyms are handled in the classic autoloader vs Zeitwerk

#RailsUpgrades| https://fastruby.io/rc2022 89 How do we make this work for Rails 5.2 and Rails 6, so we can dual boot? # Let’s define a $next_rails global var # in the Gemfile: def next? $next_rails = File.basename(__FILE__) == "Gemfile.next" end

#RailsUpgrades| https://fastruby.io/rc2022 Exercise #7 Time 5 to 10 min Using $next_rails, update config/application.rb so you can dual boot https://www.fastruby.io/rc2022#7

#RailsUpgrades| https://fastruby.io/rc2022 Exercise 7 solution # Update config/application.rb: if $next_rails config.load_defaults 6.0 config.autoloader = :zeitwerk else config.load_defaults 5.2 config.autoloader = :classic # optional line end

#RailsUpgrades | https://fastruby.io/rc2022 The Best Rails Upgrade Process This is the best rails upgrade process, proven by our team in dozens of Rails upgrade projects.

#RailsUpgrades| https://fastruby.io/rc2022 Start with a test suite you can trust We start with a test suite you can trust. It has no fl aky tests. Above 50% code coverage. And it runs fast. So you can get quick feedback.

#RailsUpgrades| https://fastruby.io/rc2022 One minor version jump at a time Then you start with one minor version jump at a time. This will start a long running branch that will include the dual booting code.

#RailsUpgrades| https://fastruby.io/rc2022 ... ✅ 2.3 👉 3.0 ✅ 3.0 👉 3.1 ✅ 3.1 👉 3.2 ✅ 3.2 👉 4.0 ✅ 4.0 👉 4.1 ✅ 4.1 👉 4.2 ✅ 4.2 👉 5.0 ✅ 5.0 👉 5.1 ✅ 5.1 👉 5.2 ✅ 5.2 👉 6.0 ✅ 6.0 👉 6.1 ✅ 6.1 👉 7.0 Gem fi le Gem fi le.next { } If you start in Rails 2.3 we would recommend this to get to Rails 6.0 You do NOT WANT to do Rails 2.3 to 6.0

#RailsUpgrades| https://fastruby.io/rc2022 Tiny PRs over One huge PR When working on the code, you want to make sure that you ship N tiny pull requests and not one huge PR.

#RailsUpgrades| https://fastruby.io/rc2022 Tiny pull requests: Easier to review Tiny pull requests are easier to review.

#RailsUpgrades| https://fastruby.io/rc2022 Tiny pull requests: Easier to review Easier to smoke test Easier to smoke test.

#RailsUpgrades| https://fastruby.io/rc2022 Tiny pull requests: Easier to review Easier to smoke test Easier to deploy Easier to deploy.

#RailsUpgrades| https://fastruby.io/rc2022 Huge, long-running upgrade branches A couple of tips for starting the upgrade process. You want to ship as many backwards-compatible changes as possible. As a matter of fact, you want to ship as many of these as possible.

#RailsUpgrades| https://fastruby.io/rc2022 Backwards- compatible changes A couple of tips for starting the upgrade process. You want to ship as many backwards-compatible changes as possible. As a matter of fact, you want to ship as many of these as possible.

#RailsUpgrades| https://fastruby.io/rc2022 For every jump: bundle install 102 For every version jump you want to make sure that you can bundle install the dependencies. Then run the entire test suite without any failures. Finally you want to smoke test your application. In some version jumps you might fi nd that the CSS or JS is broken but your test suite won’t catch it.

#RailsUpgrades| https://fastruby.io/rc2022 For every jump: bundle install bundle exec rake test For every version jump you want to make sure that you can bundle install the dependencies. Then run the entire test suite without any failures. Finally you want to smoke test your application. In some version jumps you might fi nd that the CSS or JS is broken but your test suite won’t catch it.

#RailsUpgrades| https://fastruby.io/rc2022 For every jump: bundle install bundle exec rake test smoke test & deploy For every version jump you want to make sure that you can bundle install the dependencies. Then run the entire test suite without any failures. Finally you want to smoke test your application. In some version jumps you might fi nd that the CSS or JS is broken but your test suite won’t catch it.

#RailsUpgrades| https://fastruby.io/rc2022 1. Tweak 2. Test 3. Merge And Iterate As you start working on the upgrade, you want to focus on one small change or patch at a time. Fix that deprecation warning, test that everything works fi ne, merge it, and deploy it. And start over again. And again. And again.

#RailsUpgrades | https://fastruby.io/rc2022, How To Stay Current

#RailsUpgrades| https://fastruby.io/rc2022 Once you get to the latest fi nal Rails release (v7.0.3)

#RailsUpgrades| https://fastruby.io/rc2022 Treat new deprecation warnings as exceptions

#RailsUpgrades| https://fastruby.io/rc2022 # config/environments/test.rb Rails.application.configure do # Raise on deprecation notices config.active_support.deprecation = :raise # … end

#RailsUpgrades| https://fastruby.io/rc2022 Add bundler-audit to your default rake task

#RailsUpgrades| https://fastruby.io/rc2022 # Rakefile # ... task default: “bundle:audit”

#RailsUpgrades| https://fastruby.io/rc2022 namespace :bundle do desc "Audit bundle for any known vulnerabilities" task :audit do unless system "bundle-audit check --update" exit 1 end end end

#RailsUpgrades| https://fastruby.io/rc2022 Keep up with upcoming releases 113

#RailsUpgrades| https://fastruby.io/rc2022 114 # Gemfile if next? gem 'rails', github: 'rails/rails' else gem 'rails', '~> 7.0.2.4’ end

#RailsUpgrades| https://fastruby.io/rc2022 Setup your CI server

#RailsUpgrades | https://fastruby.io/rc2022, Recap

#RailsUpgrades| https://fastruby.io/rc2022 Dual Booting Easy setup 117 It is easy to set up It is just one more environment variable.

#RailsUpgrades| https://fastruby.io/rc2022 Dual Booting Easy setup Upgrade any deps 118 We can now use dual booting to upgrade any dependency.

#RailsUpgrades| https://fastruby.io/rc2022 Dual Booting Easy setup Upgrade any deps Improved debugging 119 You can quickly switch between libraries w/ just one additional env variable. You can debug in two different shells.

#RailsUpgrades| https://fastruby.io/rc2022 Dual Booting Easy setup Upgrade any deps Improved debugging Gradual deployments 120 You can gradually deploy to production. 10% traf fi c to Rails 7.0 The rest of the traf fi c to Rails 6.1

#RailsUpgrades| https://fastruby.io/rc2022 Recap Sample app running on 6.0 121 Our sample app should be running on Rails 6.0

#RailsUpgrades| https://fastruby.io/rc2022 Recap Sample app running on 6.0 A roadmap to upgrade to 6.1 122 We now know how much work it will take to upgrade to Rails 6.1 or at least an estimation

#RailsUpgrades| https://fastruby.io/rc2022 Recap Sample app running on 6.0 A roadmap to upgrade to 6.1 A new technique to upgrade 123 We can now use dual booting to upgrade any dependency.

#RailsUpgrades | https://fastruby.io/rc2022, Feedback is welcome

#RailsUpgrades | https://fastruby.io/rc2022, Feedback is welcome 🐦 @FastRubyIO

#RailsUpgrades | https://fastruby.io/rc2022, We are hiring! (ombulabs.com/jobs) If you are interested in this sort of work, please reach out to us or fi nd us in the hallway track. Mike, Luciano, and I would be happy to answer any questions about this.

#RailsUpgrades | https://fastruby.io/rc2022, If your company needs help upgrading Rails (fastruby.io) If you need help with your upgrade and don’t have the time, feel free to contact us. We are always looking for challenging projects to upgrade.

#RailsUpgrades| https://fastruby.io/rc2022 128 Thank You! Thank you!

#RailsUpgrades | https://fastruby.io/rc2022 Questions? Do you have any questions about the pre-requisites?

#RailsUpgrades| https://fastruby.io/rc2022 Resources 1.https://github.com/clio/ten_years_rails 2.https://github.com/alphagov/e-petitions 3.https://github.com/rubyperu/ready4rails 4.https://edgeguides.rubyonrails.org/upgrading_ruby_on_rails.html#the-upgrade-process 5.https://fastruby.io/blog/tags/upgrades 6.https://semver.org 7.https://github.com/Shopify/bootboot 8.https://github.com/fastruby/rails_upgrader 9.https://edgeguides.rubyonrails.org/upgrading_ruby_on_rails.html#the-update-task 10.https://www.fastruby.io/blog/rails/upgrade/dual-booting-with-conditionals.html 11.https://www.fastruby.io/blog/upgrade-rails/dual-boot/dual-boot-with-rails-6-0-beta.html 12.http://recursion.org/incremental-rails-upgrade Here are some resources if you found this topic interesting…

RailsConf 2022 - Upgrading Rails: The Dual Boot Way

More Related Content

Similar to RailsConf 2022 - Upgrading Rails: The Dual Boot Way

More from mtoppa

Recently uploaded

In this document

RailsConf 2022 - Upgrading Rails: The Dual Boot Way