Explaining how to deploy portions of a Rails applications with Engine and GEMS.

1. deploying portions
of a Rails app with Engines
Enrico Teotti -- @agenteo

2. admin user interface
public user interface
domain logic

3. requirement
run the private and public portions of the app
on separate servers

4. service oriented architecture
first proposal
http://teotti.com/rails-service-oriented-architecture-alternative-with-components/

5. two apps sharing components via engines
second proposal
http://teotti.com/git-precommit-hooks-helping-local-ruby-gems-development/

6. one app feature flagging engines
components
third proposal

7. public_uiadmin_ui

8. config/routes.rb
Rails.application.routes.draw do
case AppRunningMode.value
when :admin
mount AdminUi::Engine => "/"
when :public
mount PublicUi::Engine => "/"
else
mount AdminUi::Engine => "/"
mount PublicUi::Engine => "/"
end
end

9. RUNNING_MODE=public rails s
RUNNING_MODE=admin rails s
http://worldwideshipping-super-secret-domain.com/admin
http://worldwideshipping.com
rails s
http://localhost:3000

10. ● are ruby gems
● are special ruby gems that provide extra
behaviour (models, views, routes, rake
tasks) to a Rails application
● they can be hosted on a gemserver or
they can live inside your repository
● can be tested in isolation
rails engines

11. admin user interface
public user interface
domain logic

12. mkdir components

13. rails plugin new admin_ui --mountable --dummy=spec/dummy -O -T
mv admin_ui components

14. admin user interface
public user interface
domain logic
admin_ui

15. proceeding without automated tests
could drive you crazy

16. shared user interface (preview)
shared domain
admin_ui

17. Rails.application.routes.draw do
# ... public routes here
mount AdminUi::Engine => "/"
end
config/routes.rb

18. gem 'admin_ui', path: 'components/admin_ui'
Gemfile

19. public user interface
admin_ui

20. public user interface
admin_ui
public_ui

21. rails plugin new public_ui --mountable --dummy=spec/dummy -O -T

22. gem 'admin_ui', path: 'components/admin_ui'
gem 'public_ui', path: 'components/public_ui'
Gemfile

23. public_uiadmin_ui

24. Gem::Specification.new do |s|
# ... other fields up here
s.name = "public_ui"
s.add_dependency "rails", "~> 4.1.1"
s.add_dependency 'jquery-rails'
s.add_dependency 'mongoid'
s.add_runtime_dependency "admin_ui"
s.add_development_dependency 'byebug'
s.add_development_dependency 'database_cleaner'
s.add_development_dependency 'rspec-rails', '2.99.0'
s.add_development_dependency 'capybara'
s.add_development_dependency 'poltergeist'
end
public_ui.gemspec

25. Gem::Specification.new do |s|
# ... other fields up here
s.name = "public_ui"
s.add_dependency "rails", "~> 4.1.1"
s.add_dependency 'jquery-rails'
s.add_dependency 'mongoid'
s.add_runtime_dependency "admin_ui"
s.add_development_dependency 'byebug'
s.add_development_dependency 'database_cleaner'
s.add_development_dependency 'rspec-rails', '2.99.0'
s.add_development_dependency 'capybara'
s.add_development_dependency 'poltergeist'
end
public_ui.gemspec

26. Rails.application.routes.draw do
case AppRunningMode.value
when :admin
mount AdminUi::Engine => "/"
when :public
mount PublicUi::Engine => "/"
else
mount AdminUi::Engine => "/"
mount PublicUi::Engine => "/"
end
end
config/routes.rb

27. the two engines are now glued together!

28. admin_ui public_ui
domain_logic

29. rails plugin new domain_logic --dummy-path=spec/dummy
--mountable -O -T

30. admin_ui public_ui
shared_ui domain_logic

31. rails plugin new shared_ui --dummy-path=spec/dummy
--mountable -O -T

32. admin_ui/app/views/cargo_preview/show.html.erb
<%# admin console stuff here %>
<%= render partial: 'shared_ui/cargos/show' %>
<%# admin spaceship here %>
public_ui/app/views/cargos/show.html.erb
<%= render partial: 'shared_ui/cargos/show' %>

33. group :admin_app do
path 'components' do
gem 'admin_ui'
gem 'legacy_migration'
end
end
group :public_app do
path 'components' do
gem 'public_ui'
end
end
Gemfile
http://teotti.com/reduce-memory-footprint-requiring-portions-of-your-component-based-rails-applications/
http://teotti.com/gemfiles-hierarchy-in-ruby-on-rails-component-based-architecture/

34. common pitfalls in Rails engines land

35. Gemfile
#gem 'domain_logic', path: 'components/domain_logic'
#gem 'shared_ui', path: 'components/shared_ui'
gem 'admin_ui', path: 'components/admin_ui'
gem 'public_ui', path: 'components/public_ui'

36. $ bundle
Resolving dependencies...
Could not find gem 'shared_ui (>= 0) ruby', which is required by gem
'admin_ui (>= 0) ruby', in any of the sources.

37. Gem::Specification.new do |s|
# ... other fields up here
s.name = "admin_ui"
s.add_dependency "rails", "~> 4.1.1"
s.add_dependency 'jquery-rails'
s.add_dependency 'mongoid'
s.add_dependency 'faraday'
s.add_dependency "domain_logic"
s.add_dependency "shared_ui"
s.add_development_dependency 'byebug'
s.add_development_dependency 'database_cleaner'
s.add_development_dependency 'rspec-rails', '2.99.0'
s.add_development_dependency 'vcr'
s.add_development_dependency 'webmock'
s.add_development_dependency 'capybara'
s.add_development_dependency 'poltergeist'
end
admin_ui.gemspec

38. Gem::Specification.new do |s|
# ... other fields up here
s.name = "admin_ui"
s.add_dependency "rails", "~> 4.1.1"
s.add_dependency 'jquery-rails'
s.add_dependency 'mongoid'
s.add_dependency 'faraday'
s.add_dependency "domain_logic"
s.add_dependency "shared_ui"
s.add_development_dependency 'byebug'
s.add_development_dependency 'database_cleaner'
s.add_development_dependency 'rspec-rails', '2.99.0'
s.add_development_dependency 'vcr'
s.add_development_dependency 'webmock'
s.add_development_dependency 'capybara'
s.add_development_dependency 'poltergeist'
end
admin_ui/admin_ui.gemspec

39. source "https://rubygems.org"
gem 'domain_logic', path: '../domain_logic'
gem 'shared_ui', path: '../shared_ui'
# Declare your gem's dependencies in admin_ui.gemspec.
# Bundler will treat runtime dependencies like base
dependencies, and
# development dependencies will be added by default to the :
development group.
gemspec
admin_ui/Gemfile

40. require

41. require 'nokogiri'
require 'faraday'
manually require
domain_logic/lib/domain_logic.rb

42. the test dummy app

43. require File.expand_path("../dummy/config/environment", __FILE__)
admin_ui/spec/rails_helper.rb
admin_ui/spec/dummy/config/boot.rb
# Set up gems listed in the Gemfile.
ENV['BUNDLE_GEMFILE'] ||= File.expand_path('../../../../Gemfile', __FILE__)
require 'bundler/setup' if File.exist?(ENV['BUNDLE_GEMFILE'])
$LOAD_PATH.unshift File.expand_path('../../../../lib', __FILE__)
Rails.application.routes.draw do
mount AdminUi::Engine => "/admin_ui"
end
admin_ui/spec /dummy/config/routes.rb

44. Rails.application.routes.draw do
mount AdminUi::Engine => "/admin_ui"
end
admin_ui/spec /dummy/config/routes.rb

45. https://github.com/shageman/the_next_big_thing/blob/master/build.sh
#!/bin/bash
unset BUNDLE_GEMFILE
result=0
if [ "$CI" == "true" ]; then
BUNDLE_PATH="$HOME/vendor/bundle"
fi
for test_script in $(find . -name test.sh); do
pushd `dirname $test_script` > /dev/null
source "$HOME/.rvm/scripts/rvm"
rvm use $(cat .ruby-version)@$(cat .ruby-gemset)
./test.sh
result+=$?
popd > /dev/null
done
if [ $result -eq 0 ]; then
echo "☺ SUCCESS"
else
echo "☹ FAILURE"
fi
exit $result
testing multiple engines

46. require_dependency "admin_ui/application_controller"
module AdminUi
class CargosController < ApplicationController
namespace application controller

47. module AdminUi
class CargosController < AdminUi::ApplicationController
namespace application controller

48. module AdminUi
class VoyagesController < ApplicationController
namespace application controller

49. module AdminUi
class VoyagesController < ApplicationController
namespace application controller

50. scaffolding and other generators

51. rails generate scaffold_controller admin_ui/cargo source destination
weight --model-name=DomainLogic::Cargo --orm=mongoid -t=''
scaffolding and other generators

52. require_dependency "admin_ui/domain_logic/application_controller"
scaffolding and other generators

53. Failures:
1) Staff booking a cargo booking a cargo fitting a pending voyage
Failure/Error: visit '/admin/cargos'
LoadError:
No such file to load -- admin_ui/domain_logic/application_controller
# ./engines/admin_ui/app/controllers/admin_ui/cargos_controller.rb:1:in `<top (required)>'
# ./spec/features/book_cargo_spec.rb:12:in `block (2 levels) in <top (required)>'
Finished in 0.03067 seconds (files took 1.85 seconds to load)
2 examples, 1 failure
scaffolding and other generators

54. Failures:
1) Staff booking a cargo booking a cargo fitting a pending voyage
Failure/Error: visit '/admin/cargos'
RuntimeError:
Circular dependency detected while autoloading constant AdminUi::AdminUi::CargosHelper
# ./engines/admin_ui/app/controllers/admin_ui/application_controller.rb:2:in `<module:AdminUi>'
# ./engines/admin_ui/app/controllers/admin_ui/application_controller.rb:1:in `<top (required)>'
# ./engines/admin_ui/app/controllers/admin_ui/cargos_controller.rb:1:in `<top (required)>'
# ./spec/features/book_cargo_spec.rb:12:in `block (2 levels) in <top (required)>'
scaffolding and other generators

55. Failures:
1) Staff booking a cargo booking a cargo fitting a pending voyage
Failure/Error: visit '/admin/cargos'
ActionView::Template::Error:
undefined local variable or method `new_domain_logic_cargo_path' for #<#<Class:0x007fb38887bb38>:0x007fb388873690>
# ./engines/admin_ui/app/views/admin_ui/cargos/index.html.erb:29:in
`_engines_admin_ui_app_views_admin_ui_cargos_index_html_erb__4343322268368929370_70204533119300'
# ./spec/features/book_cargo_spec.rb:12:in `block (2 levels) in <top (required)>'
scaffolding and other generators

56. fang:domain_logic agenteo$ rails generate mongoid:config
/Users/agenteo/.rvm/gems/ruby-2.1.2@worldwide_shipping/gems/mongoid-4.0.0/lib/rails/generators/mongoid/config/config_generator.rb:16:in `app_name': undefined
method `parent' for nil:NilClass (NoMethodError)
from /Users/agenteo/.rvm/gems/ruby-2.1.2@worldwide_shipping/gems/thor-0.19.1/lib/thor/command.rb:27:in `run'
from /Users/agenteo/.rvm/gems/ruby-2.1.2@worldwide_shipping/gems/thor-0.19.1/lib/thor/invocation.rb:126:in `invoke_command'
from /Users/agenteo/.rvm/gems/ruby-2.1.2@worldwide_shipping/gems/thor-0.19.1/lib/thor/invocation.rb:133:in `block in invoke_all'
from /Users/agenteo/.rvm/gems/ruby-2.1.2@worldwide_shipping/gems/thor-0.19.1/lib/thor/invocation.rb:133:in `each'
from /Users/agenteo/.rvm/gems/ruby-2.1.2@worldwide_shipping/gems/thor-0.19.1/lib/thor/invocation.rb:133:in `map'
from /Users/agenteo/.rvm/gems/ruby-2.1.2@worldwide_shipping/gems/thor-0.19.1/lib/thor/invocation.rb:133:in `invoke_all'
from /Users/agenteo/.rvm/gems/ruby-2.1.2@worldwide_shipping/gems/thor-0.19.1/lib/thor/group.rb:232:in `dispatch'
from /Users/agenteo/.rvm/gems/ruby-2.1.2@worldwide_shipping/gems/thor-0.19.1/lib/thor/base.rb:440:in `start'
from /Users/agenteo/.rvm/gems/ruby-2.1.2@worldwide_shipping/gems/railties-4.1.4/lib/rails/generators.rb:157:in `invoke'
from /Users/agenteo/.rvm/gems/ruby-2.1.2@worldwide_shipping/gems/railties-4.1.4/lib/rails/commands/generate.rb:11:in `<top (required)>'
from /Users/agenteo/.rvm/gems/ruby-2.1.2@worldwide_shipping/gems/railties-4.1.4/lib/rails/engine/commands.rb:19:in `require'
from /Users/agenteo/.rvm/gems/ruby-2.1.2@worldwide_shipping/gems/railties-4.1.4/lib/rails/engine/commands.rb:19:in `<top (required)>'
from bin/rails:12:in `require'
from bin/rails:12:in `<main>'
mongoid generators

59. FOLLOWUP READS
http://guides.rubyonrails.org/engines.html
https://leanpub.com/cbra
teotti.com/topics/component-based-rails-architecture
http://cbra.info/