Facepalm To Foolproof - RailsConf 2016

If you're new to Rails development, or just want some tips on deploying and running in production, this is the talk for you. Relying on real-world experience as part of the Heroku support team, we'll talk through common issues (and a few funny ones) we see when people take their "but it works in development!" app to a production environment.

Video: https://youtu.be/yDJV9mr--Yo

Transcript

1. Facepalm to Foolproof Avoiding Common Production Pitfalls Jon McCartie @jmccartie
2. Hi there! ! I’m Jon McCartie. I work at Heroku. I help people fix things.
8. AirlessBNB Vacation Rentals In Outer Space
10. $ ab -c 100 -n 500 http://airlessbnb.com/ Requests per second: 41.53 [#/sec] (mean) Time per request: 2407.916 [ms] (mean) Time per request: 24.079 [ms]
11. $ rails server -e production => Booting WEBrick
13. # Gemfile gem 'puma' # Procfile web: bundle exec puma -C config/puma.rb
14. $ ab -c 100 -n 500 http://airlessbnb.com/ Requests per second: 41.53 [#/sec] (mean) Time per request: 2407.916 [ms] (mean) Time per request: 24.079 [ms]
15. $ ab -c 100 -n 500 http://airlessbnb.com/ Requests per second: 82.94 [#/sec] (mean) Time per request: 1205.721 [ms] (mean) Time per request: 12.057 [ms]
16. ?
19. Memory Enemies 1. Memory leaks - https:/ /github.com/schneems/derailed_benchmarks - https:/ /blog.codeship.com/debugging-a-memory-leak-on-heroku/ 2. Too many web processes - how much memory does your app consume in one web worker? - how much memory do you have?
20. $ free -m total used free Mem: 8014 7528 486 -/+ buffers/cache: 2446 5567 Swap: 511 7 504 Watch Your Memory Usage
21. $ free -m total used free Mem: 8014 7528 486 -/+ buffers/cache: 2446 5567 Swap: 511 7 504 Watch Your Memory Usage
22. $ free -m total used free Mem: 8014 7528 486 -/+ buffers/cache: 2446 5567 Swap: 511 7 504 Watch Your Memory Usage
23. $ free -m total used free Mem: 8014 7528 486 -/+ buffers/cache: 2446 5567 Swap: 511 7 504 Watch Your Memory Usage
24. ➡
26. http:/ /airlessbnb.com/checkout
27. # config/production.rb config.force_ssl = true
28. server { listen 80; return 301 https://$host$request_uri; } nginx.conf
29. => ☄
30. <image src="logo.png" /> 404 - Not Found
31. # this /app/assets/images/logo.png # becomes this /public/assets/logo-a2c31b21374497ad4db1.png The Asset Pipeline
32. # Nope <img src="logo.png" /> # Yup <%= image_tag "logo.png" %>
33. # Nope .logo background-image: url("/assets/logo.png") # Yup .logo background-image: image-url("logo.png")
34. # config/initializers/assets.rb Rails.application.config.assets.precompile += %w( ads.js ads.css) Precompile List
36. "Is this happening a lot?" Uhhh… maybe?
37. "But Rails already logs to production.log" But we have multiple machines… How large is that single production.log file?
38. Logging A twelve-factor app never concerns itself with routing or storage of its output stream. It should not attempt to write to or manage logfiles. Instead, each running process writes its event stream, unbuffered, to stdout. http:/ /12factor.net/
39. # config/environment.rb config.logger = Logger.new(STDOUT) Logging
41. $ ./bin/stop-production && \ sleep 4 && \ bundle exec ./bin/start-production
43. $ mina deploy -----> Creating the build path -----> Cloning the Git repository -----> Installing gem dependencies using Bundler -----> Moving to releases/4 -----> Symlinking to current -----> Launching -----> Done. Deployed v4
44. $ heroku create sushi Creating sushi... done $ git push heroku master ----> Heroku receiving push ----> Rails app detected ----> Compiled slug size is 8.0MB sushi.herokuapp.com deployed to heroku
45. =>
46. $ cat config/s3.yml production: bucket: airlessbnb_production access_key_id: d6bb03e1e761d secret_access_key: 8921377d4ab6da9
47. # config/secrets.yml (.gitignore!) development: some_api_key: SOMEKEY # Usage Rails.application.secrets.some_api_key Storing Credentials
48. # Gemfile
 gem "dotenv-rails"
 # .env (.gitignore!)
 SECRET_KEY=foo # on heroku
 heroku config:add SECRET_KEY=foo Environment Variables
49. # in your app
 ENV["foo"] # example REDIS = Redis.new(ENV["REDIS_URL"]) Environment Variables
51. # Small App (5,761 records) User Load (2.3ms) SELECT "users".* FROM "users" WHERE "users"."username" = "jmccartie" # Large App (231,138 records) User Load (51.7ms) SELECT "users".* FROM "users" WHERE "users"."username" = "jmccartie"
52. # Small App (5,761 records) User Load (2.3ms) SELECT "users".* FROM "users" WHERE "users"."username" = "jmccartie" # Large App (231,138 records) User Load (51.7ms) SELECT "users".* FROM "users" WHERE "users"."username" = "jmccartie"
53. # Small App (5,761 records) User Load (2.3ms) SELECT "users".* FROM "users" WHERE "users"."username" = "jmccartie" # Large App (231,138 records) User Load (51.7ms) SELECT "users".* FROM "users" WHERE "users"."username" = "jmccartie"
54. class AddIndexForUsernameOnUsers < ActiveRecord::Migration def change add_index :users, :username end end Database Indexes
55. # Before User Load (51.7ms) SELECT "users".* FROM "users" WHERE "users"."username" = "jmccartie" # After User Load (1.0ms) SELECT "users".* FROM "users" WHERE "users"."username" = "jmccartie"
56. # Before User Load (51.7ms) SELECT "users".* FROM "users" WHERE "users"."username" = "jmccartie" # After User Load (1.0ms) SELECT "users".* FROM "users" WHERE "users"."username" = "jmccartie"
57. # Problem SELECT * FROM users 
 WHERE thing = 'something' 
 AND other_thing = 'something_else' # Solution add_index :users, [:thing, :other_thing] Composite Indexes
58. Intermission Just two more chapters in our story…
59. So close… I can feel that $1B valuation just around the corner…
60. # photos_controller.rb @photos = Photo.order(:name) # index.slim - @photos do |photo| = image_tag photo.url p= photo.user.username
61. Photo Load (0.2ms) SELECT "photos".* FROM "photos" ORDER BY name User Load (0.2ms) SELECT "users".* FROM "users" WHERE "users"."id" = 3 User Load (0.2ms) SELECT "users".* FROM "users" WHERE "users"."id" = 1 User Load (0.2ms) SELECT "users".* FROM "users" WHERE "users"."id" = 5 User Load (0.2ms) SELECT "users".* FROM "users" WHERE "users"."id" = 4 User Load (0.3ms) SELECT "users".* FROM "users" WHERE "users"."id" = 6 User Load (0.3ms) SELECT "users".* FROM "users" WHERE "users"."id" = 7 User Load (0.3ms) SELECT "users".* FROM "users" WHERE "users"."id" = 8 User Load (0.3ms) SELECT "users".* FROM "users" WHERE "users"."id" = 9
62. N+1
63. # nope @photos = Photo.all # yup @photos = Photo.includes(:user) N+1 Queries
64. # Old Photo Load (0.2ms) SELECT "photos".* FROM "photos" ORDER BY name User Load (0.2ms) SELECT "users".* FROM "users" WHERE "users"."id" = 3 User Load (0.2ms) SELECT "users".* FROM "users" WHERE "users"."id" = 1 User Load (0.2ms) SELECT "users".* FROM "users" WHERE "users"."id" = 5 User Load (0.2ms) SELECT "users".* FROM "users" WHERE "users"."id" = 4 User Load (0.3ms) SELECT "users".* FROM "users" WHERE "users"."id" = 2 N+1 Queries
65. # New Photo Load (0.2ms) SELECT "photos".* FROM "photos" LIMIT 0, 30 User Load (0.4ms) SELECT "users".* FROM "users" WHERE "users"."id" IN (3, 1, 5, 4, 2) N+1 Queries
66. # Gemfile gem 'bullet', group: :development N+1 Queries
67. # Logs 2016-04-25 20:40:17[INFO] N+1 Query: PATH_INFO: / photos; model: Photo => associations: [users]· Add to your finder: :include => [:users] N+1 Queries
71. Request Controller Response S3
72. SMS
73. @user.send_sms!(message)
74. Request Controller Response SMS
75. Background Workers
76. @user.send_sms!(message)
77. SendSmsJob.perform_later(@user, message)
78. Request Controller Response SMS
79. Request Controller Response SMS
80. class SendSmsJob < ActiveJob::Base queue_as :default def perform(user, message) SmsProvider.send(user.phone, message) end end
82. ❤
83. Running Your App In Production Keep learning
84. Thank you! Jon McCartie @jmccartie bit.ly/railsconf16
85. Heroku Office Hours Tomorrow, 4:10pm Heroku Booth Heroku + Rails Core Team