This document provides an overview of the history of Rails updates experienced by Shopify over 10 years of using Rails. It describes some of the major Rails version updates Shopify went through, including Rails 1.2 which introduced REST and resources, Rails 2.0 which added rescue_from and fixture dependencies, and Rails 3 which split ActiveModel. It also discusses some of the hardest parts of maintaining a large codebase through Rails updates and recommends avoiding monkey patching Rails and shipping small changes frequently to upgrade more smoothly.

1. Riding&Rails&for&10&Years
John%Duff

2. Overview
• Why%look%at%Shopify?
• History%of%Rails%updates
• Hardest%things?
• Why%upgrade?
• Recommenda;ons

3. Why$look$at$Shopify?
• Started(around(the(same(/me(as(Rails
• Never(rewri6en
• Has(used(Rails(pre(1.0(to(4.2
• Git(repository(holds(most(of(this(history

6. ~45!different!versions!of!Rails!in!produc3on

7. Going&back&in&+me

9. Going&back&in&+me
• MVC%pa(erns%already%established
• Tes5ng%already%baked%in
• deploy.rb

10. Going&back&in&+me:&rou+ng
ActionController::Routing::Routes.draw do |map|
map.index '', :controller => 'shop'
# namespaces
map.connect 'admin', :controller => 'admin/auth', :action => 'login'
map.checkout 'checkout', :controller => 'checkout/standard', :action => 'index'
# media files
map.connect 'media/:action/:id/:filename', :controller => 'media', :action => 'image'
# admin
map.connect ':controller/:action/:id', :action => 'index', :id => nil
end

11. Going&back&in&+me:&controller
class Admin::OrdersController < AdminAreaController
def index
list
render :action => 'list'
end
def list
@pages = Paginator.new(self, shop.orders.count, 20, @params[:page])
@orders = shop.orders.find(:all, :limit => 20, :offset => @pages.current.offset)
end
def show
@order = shop.orders.find(@params[:id], :include => [:line_items, :payments])
end
end

12. Going&back&in&+me:&model
class Order < ActiveRecord::Base
belongs_to :shop
has_many :line_items
belongs_to :billing_address, :class_name => 'Address'
validates_presence_of :email, :shop
validates_format_of :email, :with => Format::EMAIL, :message => 'not a valid email'
serialize :receipt, Hash
attr_accessible :email
def deliver_confirmation_email
CheckoutMailer.deliver_user_confirmation(self)
end
end

13. Going&back&in&+me:&javascript
module AjaxHelper
def appear(id, where = nil)
case where
when :first
"new Effect.Appear($('#{id}').firstChild)"
else
"new Effect.Appear('#{id}')"
end
end
end

14. Going&back&in&+me:&more
• Sweepers
• Observers
• rhtml/views
• Dependencies/in/vendor/or/submodules
• FastCGI/to/interface/with/the/webserver

15. --------------------------------------------------
Language files code
--------------------------------------------------
Ruby 177 4967
Javascript 10 2436
YAML 33 1465
Ruby HTML 61 1399
CSS 4 638
SQL 2 573
HTML 2 41
Bourne Again Shell 1 2
--------------------------------------------------
SUM: 290 11521
--------------------------------------------------

16. A"lot"has"changed,"but"a"lot"is"s2ll"the"same

17. Rails&1.2

18. Rails&1.2
• REST&and&Resources
• Mul2byte&support
• Rou2ng&and&auto8loading&rewri;en
• Formats&and&respond_to

19. Rails&1.2:&Formats&and&respond_to
ActionController::Routing::Routes.draw do |map|
map.connect ':controller/:action.:format'
map.connect ':controller/:action/:id.:format'
end
class Admin::OrdersController < AdminAreaController
def list
@pages = Paginator.new(self, shop.orders.count(:all), 25, params[:page])
@orders = shop.orders.find(:all, :limit => 25, :offset => @pages.current.offset)
respond_to do |format|
format.html { render :action => 'list' }
format.csv { render_export_file('orders.csv', Mime::CSV, CSV.export(@orders)) }
end
end
end

20. Rails&1.2:&REST&and&Resources
ActionController::Routing::Routes.draw do |map|
map.resources :collects, :path_prefix => "admin", :controller => "admin/collects"
end
class Admin::CollectsController < AdminAreaController
def create
@collect = Collect.new(:product => @product, :collection => @collection)
@collect.save ? head(:created) : head(:precondition_failed)
end
def destroy
@collect = Collect.find(params[:id])
if @collect and shop.products.exists?(@collect.product_id)
@collect.destroy
head :ok
else
head :not_found
end
end
end

21. Rails&1.2:&more
• Ini%al(RESTful(urls(looked(like(/orders/1;edit
• Changed(in(Rails(1.2.4(to(/orders/1/edit

22. Rails&2.0

23. Rails&2.0
• Added%rescue_from
• Fixture%dependencies
• Rou5ng%namespaces
• Mul5%view%responses
• Ac5onWebService%out,%Ac5veResource%in
• JSON%serializa5on

24. Rails&2.0:&rescue_from
# before
def rescue_action(e)
case e
when MerchantCredentialError
when IrreparableGoogleCheckoutError
when ActiveRecord::RecordNotFound
else
end
end
# after
rescue_from MerchantCredentialError do |exception|
response.headers["WWW-Authenticate"] = %(Basic realm="Ping Backend")
render :status => "401 Unauthorized"
end

25. Rails&2.0:&Fixture&dependencies
# before
bigcheese_blog:
id: 1
shop_id: 1
title: Mah Blog
updated_at: 2006-02-02
# after
bigcheese_blog:
shop: snowdevil
title: Mah Blog
updated_at: 2006-02-02
# Fixtures.identify(:snowdevil) when ambiguous

26. Rails&2.0:&Rou-ng&namespaces
# before
map.resources :fulfillment_services, :path_prefix => 'admin/preferences',
:controller => 'admin/preferences/fulfillment_services'
# after
admin.namespace :admin do |admin|
admin.namespace :preferences do |prefs|
prefs.resources :fulfillment_services
end
end

27. Rails&2.1

28. Rails&2.1:&config.gems
# config/environment.rb
Rails::Initializer.run do |config|
config.gem "right_aws"
config.gem "entp-multipass", :source => 'http://gems.github.com'
end

29. Rails&2.3

30. Rails&2.3
• Rack
• accepts_nested_a-ributes
• find_in_batches
• improvements7to7Rails7Engines
• Rails7metal
• Applica<on7templates

31. Rails&2.3:&Rack
# config/environment.rb
ActionController::Dispatcher.middleware.insert_before 'Rack::Lock', CommonBlacklist
# lib/common_blacklist.rb
class CommonBlacklist
def initialize(app)
@app = app
end
def call(env)
if env['REQUEST_URI'] =~ /^/feedsplitter.php/
[404, {"Content-Type" => "text/plain"}, ['[Filtered]']]
else
@app.call(env)
end
end
end

32. Rails&2.3:&accepts_nested_a2ributes
# before
class ApiClient < ActiveRecord::Base
attr_accessible :new_link_attributes, :existing_link_attributes
def new_link_attributes=(link_attributes)
link_attributes.each do |attributes|
links.build(attributes)
end
end
# more shenanigans
end
# after
class ApiClient < ActiveRecord::Base
attr_accessible :links_attributes
accepts_nested_attributes_for :links, :allow_destroy => true
end

33. Rails&3

34. Rails&3
• Arel
• Bundler
• Ac+ve-model-broken-up
• js/test/orm-agnos+c

35. Rails&3:&Arel
# before
class StoredAsset < ActiveRecord::Base
def self.with_prefix(prefix)
scoped(:conditions => {:prefix => prefix.to_s})
end
end
# after
class StoredAsset < ActiveRecord::Base
scope :with_prefix, lambda { |prefix| where(:prefix => prefix.to_s) }
end

36. Rails&3:&Bundler
# before
# config/environment.rb
Rails::Initializer.run do |config|
config.gem "right_aws"
end
# after
# Gemfile
source "http://gems.rubyforge.org"
source "http://gems.github.com"
gem "rack", '1.0.1'
gem "rails", '2.3.5'

37. Rails&3.1&and&3.2

38. Rails&3.1&and&3.2
• Assets&pipeline
• JQuery&the&default&JS&library
• Lots&of&internal&API&changes
• 248&changed&files&with&1,366&addiAons&and&1,656&deleAons

39. Rails&4.0

40. Rails&4.0
• Ruby&2
• Turbolinks
• Russian&doll&caching
• Strong&parameters
• Remove&observers
• Remove&hash&and&dynamic&finders

41. Rails&4.0:&dynamic&finders
# before
shop.customers.find_or_initialize_by_email(data[:email])
PaymentProvider.find_all_by_type(:direct)
# after
shop.customers.where(data.slice(:email)).first_or_initialize
PaymentProvider.where(type: 'direct')

42. Rails&4.1

43. Rails&4.1
• Spring(applica,on(preloader
• Variant(templates

44. Rails&4.1:&Variant&templates
class ApplicationContoller < ActionController::Base
before_action :set_mobile_variant
def set_mobile_variant
request.variant = :mobile if request.user_agent =~ USER_AGENT_PATTERN
end
end
# views/admin/customers/show.html+mobile.erb

45. That%brings%us%to%today

46. Started'easy,'got'hard

47. Hardest(things?
• Marshaling+changes
• Maintaining+momentum+with+a+large+team
• Large+codebase+with+lots+of+edge+cases
• Performance+regressions

48. Why$upgrade?
• New%features
• Be-er%security
• Hiring
• Codebase%longevity

49. Recommenda)ons
• Avoid'monkey'patching'Rails
• Keep'dependencies'low
• Ship'small'changes'early'and'o:en
• Parallel'CI
• Dedicate'a'team
• Ship'to'isolated'produc@on'servers

50. john.duff@shopify.com
@johnduff