Slides from 2023/03/09 NYC.rb A presentation about managing large Ruby applications using gems. Here's an example repository: https://github.com/agenteo/lab-best_health Find more blog posts I wrote (in 2016) on the topic here: https://teotti.com/create-dependency-structures-with-local-ruby-gems/ and here https://teotti.com/topics/maintainability/

1. build and maintain large Ruby
applications
Enrico Teotti - @agenteo - http://teotti.com
enrico.teotti@gmail.com
starting shortly

2. build and maintain large Ruby
applications
Enrico Teotti - @agenteo - http://teotti.com
http://www.slideshare.net/agenteo/build-and-maintain-large-ruby-applications-ruby-conf-australia-2016

3. wall.rb
spec.description = ”Builds and maintains huge Ruby apps”

6. – Any Java developer
“Ruby is a toy language.”

7. automate
d testing
team
diligence
local
Ruby
gems

8. Booking + Driving + Billing

9. Booking + Driving + Billing

10. Booking Driving Billing

11. 2001 2003
2007
2018

13. Ruby files in a project are like ingredients in a recipe

14. yeast
honey
salt
milk flour
water
lard
sugar
arugula
squacquerone
prosciutto

15. piadina
yeast
honey
salt
milk flour
water
lard
sugar
arugula
squacquerone
prosciutto

19. 3 months later

20. piadina
the curse of
knowledge
yeast
honey
salt
milk flour
water
lard
sugar
arugula
squacquerone
prosciutto

21. 6 months later
– The law of continuing change (1974) Lehman, M
“Any software system used in the real-world must change or
become less and less useful in that environment.”
– The law of increasing complexity (1974) Lehman, M
“As a program evolves, it becomes more complex, and extra
resources are needed to preserve and simplify its structure.”

22. biscuits
mozzarella
sunflower oil
carrots
eggs
tomato puree
basil
mascarpone
coffee
cacao
yeast
honey
salt
milk flour
water
lard
sugar
arugula
squacquerone
prosciutto
oregano

23. sunflower oil
carrots
gs
tomato puree
basil
mascarpone
coffee
cacao
yeast
honey
salt
milk flour
water
lard
sugar
arugula
squacquerone
prosciutto
oregano
piadina
pizza margherita
tiramisu
carrot cake

24. white ingredients
green ingredients
red ingredients
yellowish ingredients
orange ingredients
dark ingredients

25. white ingredients
green ingredients
classes grouped
by design pattern
ls -l app/
├── controllers
├── helpers
├── models
├── presenters
├── services
├── serializers
├── strategies
├── utils
└── views
http://teotti.com/application-directories-named-as-architectural-patterns-antipattern/

26. piadina
pizza margherita
tiramisu
carrot cake

28. namespaces

29. # lib/blog/after_publish.rb
module Blog
class AfterPublish
private
def subscribe_blogger_to_promotion
Promotions::Submission.new
end
end
end
# lib/promotions/new_member.rb
module Promotions
class Submission
private
def fetch_member(id)
# lib/membership/finder.rb
Membership::Finder.new(id)
end
end
end
promotions
blog membership
namespaces
context context

30. # lib/blog/after_publish.rb
module Blog
class AfterPublish
private
def subscribe_blogger_to_promotion
Promotions::Submission.new
end
end
end
# lib/promotions/new_member.rb
module Promotions
class Submission
private
def fetch_member(id)
# lib/membership/finder.rb
Membership::Finder.new(id)
end
end
end
promotions
blog membership
namespaces
context context

31. promotions
name
finder
blog membership
main Ruby application
1 year
lib

32. promotions
name
finder
blog membership
main Ruby application
1 year
lib

33. promotions
room
decorator
name
finder
blog membership
recipes
main Ruby application
comments
lib
3 years

34. promotions
room
decorator
name
finder
blog membership
recipes
main Ruby application
comments
lib
3 years

35. that’s the Ruby way

36. is that the Ruby way?

37. piadina worktop
tiramisu worktop
shared worktop
carrot cake worktop
pizza worktop

38. local Ruby gems

41. A
main Ruby application
piadina gem

42. A
piadina gem
pizza gem
C
shared
ingredients gem
main Ruby application

43. A
piadina gem
pizza gem
C
shared
ingredients gem
main Ruby application
spec.add_dependency "shared_ingredients"
# local_gems/pizza/pizza.gemspec

44. A
piadina gem
pizza gem
C
shared
ingredients gem
main Ruby application
spec.add_dependency "shared_ingredients"
# local_gems/piadina/piadina.gemspec

46. piadina gem
pizza gem
C
shared
ingredients gem
main Ruby application
desserts gem
D
A

48. piadina gem
pizza gem
C
shared
ingredients gem
main Ruby application
desserts gem
D
A
E
calzone gem
pizza dough gem
F
Conway’s Law
“organizations which design systems … are constrained to produce designs which
are copies of the communication structures of these organizations"

49. piadina gem
pizza gem
shared
ingredients gem
main Ruby application
desserts gem
D
A
calzone gem
pizza dough gem
F
E
C

50. http://teotti.com/create-dependency-structures-with-local-ruby-gems/
code & examples

51. A
C
D
B
E
your health plan
drug information
claims platform
product
information
membership
gem
gem
gem
gem
gem
dependency
main Ruby application
Sinatra / Rails / Hanami
http://teotti.com/create-dependency-structures-with-local-ruby-gems/

52. ├── Gemfile
├── Gemfile.lock
├── local_gems
├── run.rb
└── spec
ruby script that
triggers entry point
gem’s behaviour
require 'health_plan'
subscriber_id = 'ASE123456789'
aggregated_drug_information = HealthPlan::Aggregator.new(subscriber_id)
puts aggregated_drug_information.details
main Ruby application

53. ├── Gemfile
├── Gemfile.lock
├── local_gems
├── run.rb
└── spec
path 'local_gems' do
gem 'health_plan'
end
source 'https://rubygems.org'
group :test do
gem 'rspec'
end
bundler’s Gemfile
uses a path directive
to find local gems
main Ruby application

54. ├── Gemfile
├── Gemfile.lock
├── local_gems
├── run.rb
└── spec
bundler’s Gemfile
uses a path directive
to find local gems
path 'local_gems' do
gem 'health_plan'
end
source 'https://rubygems.org'
group :test do
gem 'rspec'
end
main Ruby application

55. ├── Gemfile
├── Gemfile.lock
├── local_gems
├── run.rb
└── spec
directory where your local gems are
$ cd local_gems
$ bundle gem health_plan
create health_plan/Gemfile
create health_plan/Rakefile
create health_plan/LICENSE.txt
create health_plan/README.md
create health_plan/.gitignore
create health_plan/health_plan.gemspec
create health_plan/lib/health_plan.rb
create health_plan/lib/health_plan/version.rb
Initializing git repo in /Users/me/code/lab/gem-dependency-structure/local_gems/health_plan
$ rm -Rf health_plan/.git*
main Ruby application

56. # local_gems/health_plan/health_plan.gemspec
lib = File.expand_path('../lib', __FILE__)
$LOAD_PATH.unshift(lib) unless $LOAD_PATH.include?(lib)
require 'health_plan/version'
Gem::Specification.new do |spec|
spec.name = "health_plan"
spec.version = HealthPlan::VERSION
spec.authors = ["Enrico Teotti"]
spec.email = ["enrico.teotti@gmail.com"]
spec.summary = %q{Write a short summary. Required.}
spec.description = %q{Write a longer description. Optional.}
spec.homepage = ""
spec.license = "MIT"
spec.files = `git ls-files -z`.split("x0")
spec.executables = spec.files.grep(%r{^bin/}) { |f| File.basename(f) }
spec.test_files = spec.files.grep(%r{^(test|spec|features)/})
spec.require_paths = ["lib"]
spec.add_development_dependency "bundler", "~> 1.7"
spec.add_development_dependency "rake", "~> 10.0"
├── Gemfile
├── Gemfile.lock
├── local_gems
│ └── health_plan
├── run.rb
└── spec
spec.add_development_dependency "rspec", "3.4.0"
end
your health plan

57. # local_gems/health_plan/health_plan.gemspec
lib = File.expand_path('../lib', __FILE__)
$LOAD_PATH.unshift(lib) unless $LOAD_PATH.include?(lib)
require 'health_plan/version'
Gem::Specification.new do |spec|
spec.name = "health_plan"
spec.version = HealthPlan::VERSION
spec.authors = ["Enrico Teotti"]
spec.email = ["enrico.teotti@gmail.com"]
spec.summary = %q{Write a short summary. Required.}
spec.description = %q{Write a longer description. Optional.}
spec.homepage = ""
spec.license = "MIT"
spec.files = `git ls-files -z`.split("x0")
spec.executables = spec.files.grep(%r{^bin/}) { |f| File.basename(f) }
spec.test_files = spec.files.grep(%r{^(test|spec|features)/})
spec.require_paths = ["lib"]
spec.add_development_dependency "bundler", "~> 1.7"
spec.add_development_dependency "rake", "~> 10.0"
├── Gemfile
├── Gemfile.lock
├── local_gems
│ └── health_plan
├── run.rb
└── spec
spec.add_development_dependency "rspec", "3.4.0"
end
your health plan

58. # local_gems/health_plan/spec/health_plan/aggregator_spec.rb
require 'spec_helper'
describe HealthPlan::Aggregator do
describe "#details" do
it "should not throw exceptions" do
aggregator = HealthPlan::Aggregator.new(12345)
expect(aggregator.details).to eq({ name: 'The full package plan'})
end
end
end
your health plan
├── Gemfile
├── Gemfile.lock
├── local_gems
│ └── health_plan
├── run.rb
└── spec

59. # local_gems/health_plan/lib/health_plan/aggregator.rb
module HealthPlan
class Aggregator
def initialize(id)
@subscriber_id = id
end
def details
{ name: 'The full package plan'}
end
end
end
# local_gems/health_plan/lib/health_plan.rb
require "health_plan/version"
require "health_plan/aggregator"
module HealthPlan
end
gem entry point
your health plan
├── Gemfile
├── Gemfile.lock
├── local_gems
│ └── health_plan
├── run.rb
└── spec

60. ├── Gemfile
├── Gemfile.lock
├── local_gems
│ ├── drug_information
│ └── health_plan
├── run.rb
└── spec
your health plan
drug information
main Ruby application
$ cd local_gems
$ bundle gem drug_information
create drug_information/Gemfile
create drug_information/Rakefile
create drug_information/LICENSE.txt
create drug_information/README.md
create drug_information/.gitignore
create drug_information/drug_information.gemspec
create drug_information/lib/drug_information.rb
create drug_information/lib/drug_information/version.rb
drug information

61. # local_gems/health_plan/spec/health_plan/aggregator_spec.rb
require 'spec_helper'
describe HealthPlan::Aggregator do
describe "#details" do
let(:fetched_drugs) { 'something' }
before do
fetcher_double = double('DrugInformation::Fetcher', details: fetched_drugs)
allow(DrugInformation::Fetcher).to receive(:new).and_return(fetcher_double)
end
it "should not throw exceptions" do
aggregator = HealthPlan::Aggregator.new(12345)
expect(aggregator.details).to eq({ name: 'The full package plan’,
drugs: fetched_drugs })
end
end
end
your health plan
├── Gemfile
├── Gemfile.lock
├── local_gems
│ ├── drug_information
│ └── health_plan
├── run.rb
└── spec

62. your health plan
lib = File.expand_path('../lib', __FILE__)
$LOAD_PATH.unshift(lib) unless $LOAD_PATH.include?(lib)
require 'health_plan/version'
Gem::Specification.new do |spec|
spec.name = "health_plan"
spec.version = HealthPlan::VERSION
spec.authors = ["Enrico Teotti"]
spec.email = ["enrico.teotti@gmail.com"]
spec.summary = %q{Write a short summary. Required.}
spec.description = %q{Write a longer description. Optional.}
spec.homepage = ""
spec.license = "MIT"
spec.files = `git ls-files -z`.split("x0")
spec.executables = spec.files.grep(%r{^bin/}) { |f| File.basename(f) }
spec.test_files = spec.files.grep(%r{^(test|spec|features)/})
spec.require_paths = ["lib"]
spec.add_development_dependency "bundler", "~> 1.7"
spec.add_development_dependency "rake", "~> 10.0"
spec.add_development_dependency "rspec", "3.4.0"
spec.add_dependency "drug_information"
end
# local_gems/health_plan/health_plan.gemspec
├── Gemfile
├── Gemfile.lock
├── local_gems
│ ├── drug_information
│ └── health_plan
├── run.rb
└── spec

63. your health plan
# local_gems/health_plan/Gemfile
├── Gemfile
├── Gemfile.lock
├── local_gems
│ ├── drug_information
│ └── health_plan
├── run.rb
└── spec
path '..'
source 'https://rubygems.org'
‘..’ represents the parent directory

64. # local_gems/health_plan/lib/health_plan/aggregator.rb
module HealthPlan
class Aggregator
def initialize(id)
@subscriber_id = id
end
def details
fetched_drug_info = DrugInformation::Fetcher.new(@subscriber_id)
{ name: 'The full package plan', drugs: fetched_drug_info.details }
end
end
end
# local_gems/health_plan/lib/health_plan.rb
require "health_plan/version"
require "health_plan/aggregator"
require "drug_information"
module HealthPlan
end
gem entry point
your health plan
├── Gemfile
├── Gemfile.lock
├── local_gems
│ ├── drug_information
│ └── health_plan
├── run.rb
└── spec
require dependent gem
http://teotti.com/create-dependency-structures-with-local-ruby-gems/

65. automate
d testing

66. A
C
D
B
E
main Ruby application
unit tested
unit tested
unit tested
unit tested
unit tested
acceptance tests

67. A
C
main Ruby application
B
loaded in memory, deamon or webserver
unit tested
unit tested
not unit tested
http://teotti.com/create-dependency-structures-with-local-ruby-gems#gotcha-flaky-bugs-caused-by-missing-requirement-statements

68. A
C
D
B
E
Jurassic Ruby application
developer
CEO
CTO
QA “resource”
QA “resource”

69. team
diligence

70. A
C
D
B
E
main Ruby application
F
H
I L
membership
payment API
payment
platform
bank transaction
credit card
transaction
your health plan
API
drug information
claims platform
product
information
membership

71. A
C
D
B
E
main Ruby application
F
H
I L
membership
payment API
payment
platform
bank transaction
credit card
transaction
your health plan
API
drug information
claims platform
product
information
membership

72. A
C
D
B
E
main Ruby application
F
H
I L
membership
payment API
payment
platform
bank transaction
credit card
transaction
your health plan
API
drug information
claims platform
product
information
membership

73. A
C
D
B
E
main Ruby application
F
H
I L
membership
payment API
payment
platform
bank transaction
credit card
transaction
your health plan
API
drug information
claims platform
product
information
membership

74. A
C
D
B
E
main Ruby application
F
H
I L
membership
payment API
payment
platform
bank transaction
credit card
transaction
your health plan
API
drug information
claims platform
product
information
membership

75. A
C
D
B
E
main Ruby application
F
H
I L
I find your use of
Gems disturbing
Do I really look like
a guy with a plan?
*nods then deletes
your Gem*

77. http://teotti.com/rails-service-oriented-architecture-alternative-with-components/
to be continued…
premature use of SOA

78. A
C
D
B
E
main Ruby application
F
H
I L
membership
payment API
payment
platform
bank transaction
credit card
transaction
your health plan
API
drug information
claims platform
product
information
membership

79. main Ruby application
your health
plan API
drug
information
claims
platform
product
information
membership
membership
payment
API
payment
platform
bank
transaction
credit card
transaction

80. deploy parts of a monolith
http://teotti.com/deploy-parts-of-a-ruby-on-rails-application/

81. monolithic Ruby application
DB

82. editorial admin ui
persistence
site search
componentized Ruby application
public content ui
shared ui
DB

83. deploy@adminServer $ RUNNING_MODE=admin puma

84. editorial admin ui
persistence
site search
Rails application
public content ui
shared ui
DB

85. deploy@publicServer $ RUNNING_MODE=public puma
http://teotti.com/deploy-parts-of-a-ruby-on-rails-application/

86. legacy migration

87. editorial admin ui
persistence
site search
Rails application
public content ui
shared ui
DB
legacy
migration
AWS
SQS
massage and
transform content
legacy system
pull legacy
content

88. https://medium.com/gusto-
engineering/laying-the-cultural-and-
technical-foundation-for-big-rails-
6b5ab78349ed
https://github.com/Shopify/packwerk

89. formerly lotus.rb
hanami.rb

91. automate
d testing
team
diligence
local
Ruby
gems

92. automate
d testing
team
diligence
local
Ruby
gems
team in a fixed
mindset

93. run an experiment

94. automate
d testing
team
diligence
local
Ruby
gems

95. automate
d testing
team
diligence
local
Ruby
gems

96. automate
d testing
team
diligence
local
Ruby
gems

97. Enrico Teotti - @agenteo - http://teotti.com