RailsConf 2019: Upgrade Rails 101 Workshop

@etagwerker | #RailsUpgrades | https://fastruby.io/upgrade
Upgrade Rails 101
The Roadmap to
Smooth Upgrades
RailsConf 2019

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Who is this
workshop for?
2

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Workshop
Outline
3

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Goal:
The Upgrade
Roadmap
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fastruby.io/
upgrade
5

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#RailsUpgrades
6

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Ernesto Tagwerker
(he/him)

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Thanks to
my main
sponsor!

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Founder &
Software Engineer
at Ombu Labs

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Founder &
Software Engineer
at FastRuby.io

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- “Upgrading
Rails is easy,
right?”
- “Right, right,
easy…”

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Questions are
welcome

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Pre-Requisites

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An outdated
Rails application

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$ bundle install

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$ bundle exec rake

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$ bundle exec rspec

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$ bundle exec rake test

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If you don’t
have an outdated
Rails app…

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$ git clone \
[email protected]:fastruby/e-petitions.git

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$ cd e-petitions
$ ./bin/setup

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Questions?

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Exercise #1:
Check Pre-Requisites
Time: 10 minutes
https://fastruby.io/upgrade#1

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Is your app
ready
for an upgrade?

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bundle update rails ?

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Does your
test suite
succeed?
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Does your app
have decent
test coverage?
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Exercise #2:
Calculate Test
Coverage

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SimpleCov
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# Gemfile
group :test do
gem 'simplecov', require: false
end

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# spec/spec_helper.rb
if ENV['COVERAGE'] == 'true'
require 'simplecov'
SimpleCov.start 'rails'
end

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$ COVERAGE=true bundle exec rake

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Questions?

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Exercise #2:
Check Test Coverage
Time: 15 minutes

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Is upgrading a
good idea?

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Upgrading is
always
a good idea
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Let’s assume your
application is
well covered
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Trust
The Process

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Gradual
version
jumps
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...
✅ 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
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Gemﬁle Gemﬁle.next
{ }

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For every version jump:
bundle install
bundle exec rake
Smoke test
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Ship
backwards-compatible
changes ﬁrst
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Every
deprecation
warning is a story
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Every
failing scenario
is a story
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Tiny Pull Requests
over
One Huge PR
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Tiny Changesets
over
Huge Changesets
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1. Tweak
2. Test
3. Merge
And
Iterate

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The Version Jump
Pull Request
is Last
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Pessimistic
Dependencies
Checkup

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SemVer
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..
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Rails 5.2.3
MAJOR: 5
MINOR: 2
PATCH: 3
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Dependencies
should be
pessimistic*
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# Gemfile (fixed version)
source 'https://rubygems.org'
gem 'rails', '4.2.7'

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$ bundle update
$ cat Gemfile.lock | grep rails
rails (4.2.7)

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# Gemfile (pessimistic versions)
gem 'rails', '~> 4.2.7'

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$ bundle update
$ cat Gemfile.lock | grep rails
rails (4.2.11.1)

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Exercise #3:
Relax your Gemﬁle

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Analyze your
Gemﬁle
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$ bundle outdated
Fetching gem metadata from https://rubygems.org/.
Resolving dependencies.....
Outdated gems included in the bundle:
* actioncable (newest 5.2.3, installed 5.1.6)
* actionmailer (newest 5.2.3, installed 5.1.6)
* actionpack (newest 5.2.3, installed 5.1.6)
* actionview (newest 5.2.3, installed 5.1.6)
...

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For every ﬁxed
dependency declaration:
- Turn it into a pessimistic
declaration
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For every ﬁxed
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$ bundle update

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For every ﬁxed
65
$ bundle exec rake

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Does your build pass?
- Submit a PR
- Create a story
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… and move on to the
next ﬁxed dependency

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Remember:
One at
a time
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Questions?

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Exercise #3:
Relax your Gemﬁle
Time: 10 minutes

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What
happened?
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Dual Boot:
Bundle Install

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Let’s bump that
Rails version
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Dual boot:
There are many gems for that
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# Gemfile
group :development do
gem "ten_years_rails",
git: "https://github.com/fastruby/ten_years_rails_conf_2018.git",
branch: "fixes/ruby-2-2-syntax-error"
end

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$ bundle install

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$ bundle_report outdated
cucumber-rails 1.4.0: released over 5 years ago (latest
version, 1.7.0, released 11 days ago)
rack-test 0.6.3: released over 4 years ago (latest
version, 1.1.0, released 9 months ago)
cucumber-wire 0.0.1: released over 3 years ago (latest
cucumber-core 1.5.0: released almost 3 years ago (latest
cucumber 2.4.0: released almost 3 years ago (latest
arel 6.0.4: released over 2 years ago (latest version,
9.0.0, released over 1 year ago)
...
...
...
35 of the 143 gems are out-of-date (24%)

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$ bundle_report compatibility --rails-version=6.0.0.rc1
=> Incompatible with Rails 6.0.0.rc1 (with new versions that ar
compatible):
These gems will need to be upgraded before upgrading to Rails
6.0.0.rc1.
rails-controller-testing 1.0.2 - upgrade to 1.0.4
responders 2.4.0 - upgrade to 2.4.1
2 gems incompatible with Rails 6.0.0.rc1
(this is for an app running Rails 5.1.4)

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$ next --init
Created Gemfile.next (a symlink to your Gemfile). Your Gemfile
has been modified to support dual-booting!
There's just one more step: modify your Gemfile to use a newer
version of Rails using the `next?` helper method.
For example, here's how to go from 5.2.3 to 6.0:
if next?
gem "rails", "6.0.0"
else
gem "rails", "5.2.3"
end

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# Gemfile
def next?
File.basename(__FILE__) ==
"Gemfile.next"
end
gem 'rails', '~> 5.1.4’

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# Gemfile
if next?
gem 'rails', '~> 5.2.3'
else
gem 'rails', '~> 5.1.4'
end

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$ next bundle install

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$ BUNDLE_GEMFILE=Gemfile.next \
bundle install

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Incompatibilities
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bundle install
Bundler could not find compatible versions for gem "activesupport":
In snapshot (Gemfile.lock):
activesupport (= 4.2.1)
In Gemfile:
activeadmin was resolved to 1.0.0.pre4, which depends on
arbre (>= 1.0.2, ~> 1.0) was resolved to 1.1.1, which depends on
activesupport (>= 3.0.0)
activeadmin was resolved to 1.0.0.pre4, which depends on
inherited_resources (~> 1.6) was resolved to 1.7.0, which depends on .

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Try to ﬁx
incompatibilities
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#DownTheRabbitHole

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You might have to remove
dependencies, create user
stories, and move on
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Exercise #4:
next bundle install
Time: 15 minutes

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Dual Boot:
Test Suite

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Assuming you can now
next bundle install
successfully...
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# On Rails > 4.2
$ next bundle exec rake app:update

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# On Rails <= 4.2
$ next bundle exec rake rails:update

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$ next bundle exec rake

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Failures
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bundle exec rake
rake aborted!
Bundler::GemRequireError: There was an error while trying to load
the gem 'test_after_commit'.
Gem Load Error is: after_commit testing is baked into rails 5, you
no longer need test_after_commit gem
Backtrace for gem load error is:
/Users/etagwerker/.rvm/gems/ruby-2.4.5@petitions/gems/
test_after_commit-1.1.0/lib/test_after_commit.rb:4:in `(required)>'
/Users/etagwerker/.rvm/rubies/ruby-2.4.5/lib/ruby/site_ruby/2.4.0/
bundler/runtime.rb:81:in `require'
bundler/runtime.rb:81:in `block (2 levels) in require'
bundler/runtime.rb:76:in `each'

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# Gemfile
group :test do
gem 'nokogiri'
gem 'shoulda-matchers'
gem ‘pickle'
unless next?
gem ‘test_after_commit'
end
end

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bundle exec rake
NoMethodError:
undefined method `hide_action' for
Delayed::Web::ApplicationController:Class
# ./config/initializers/delayed_web.rb:10:in `block in (required)>'
# ./config/initializers/delayed_web.rb:7:in `class_eval'
# ./config/initializers/delayed_web.rb:7:in `'
# /Users/etagwerker/.rvm/gems/ruby-2.4.5@petitions/gems/
activesupport-5.0.7.2/lib/active_support/dependencies.rb:287:in
`load'
`block in load'
`load_dependency'

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# config/initializers/delayed_web.rb
Delayed::Web::ApplicationController.class_eval do
include Authentication, FlashI18n
hide_action :admin_request?
def admin_request?
true
end
protected
def admin_login_url
main_app.admin_login_url
end
end

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# config/initializers/delayed_web.rb
Delayed::Web::ApplicationController.class_eval do
include Authentication, FlashI18n
protected
def admin_request?
true
end
def admin_login_url
main_app.admin_login_url
end
end

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Deprecation
Warnings
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$ BUNDLE_GEMFILE=Gemfile.next bundle exec rake
DEPRECATION WARNING: The success? predicate is deprecated and
will be removed in Rails 6.0. Please use successful? as
provided by Rack::Response::Helpers. (called from block (3
levels) in at /Users/etagwerker/Projects/
ombulabs/fastruby.io/spec/controllers/
contacts_controller_spec.rb:20)
.DEPRECATION WARNING: The success? predicate is deprecated
and will be removed in Rails 6.0. Please use successful? as
..DEPRECATION WARNING: The success? predicate is deprecated
and will be removed in Rails 6.0. Please use successful? as
..........

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Find References
To Deprecated
API

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https://edgeguides.rubyonrails.org/
upgrading_ruby_on_rails.html
Ofﬁcial Guides

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Unofﬁcial Guides
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1.https://fastruby.io/blog/rails/upgrades/upgrade-to-rails-3.html
2.https://fastruby.io/blog/rails/upgrades/upgrade-to-rails-3-1.html
3.https://fastruby.io/blog/rails/upgrades/upgrade-to-rails-3-2.html
4.https://fastruby.io/blog/rails/upgrades/upgrade-rails-from-3-2-to-4-0.html
7.https://fastruby.io/blog/rails/upgrades/active-record-5-1-api-changes.html

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http://railsdiff.org/
RailsDiff

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Find In
Project
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Exercise #5:
next bundle exec rake
Time: 15 minutes

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What
happened?
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How To
Stay Current
How To
Stay Current

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Treat new
deprecation warnings
as exceptions
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# config/environments/test.rb
Rails.application.configure do
# ...
# Raise on deprecation notices
config.active_support.deprecation = :raise
# ...
end
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Add bundler-audit
to your default
rake task
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# Rakefile
# ...
task default: %i[
bundle:audit brakeman:check
spec spec:javascripts cucumber
]
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namespace :bundle do
desc "Audit bundle for any known vulnerabilities"
task :audit do
unless system "bundle-audit check --update"
exit 1
end
end
end
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Keep up with
the upcoming
releases
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# Gemfile
git_source(:github) do |repo_name|
repo_name = "#{repo_name}/#{repo_name}" unless
repo_name.include?("/")
"https://github.com/#{repo_name}.git"
end
if next?
gem 'rails', github: 'rails/rails'
else
gem 'rails', '~> 6.0.0.rc1'
end

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Exercise #6:
Set Up to Stay Current
Time: 5 minutes

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@etagwerker
#RailsUpgrades
fastruby.io
Feedback is welcome

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Thank You!

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Resources
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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.http://railsdiff.org
10.https://github.com/hintmedia/moderate_parameters
11.https://edgeguides.rubyonrails.org/upgrading_ruby_on_rails.html#the-update-task

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RailsConf 2019: Upgrade Rails 101 Workshop

RailsConf 2019: Upgrade Rails 101 Workshop

Ernesto Tagwerker

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