Facepalm to Foolproof - RubyConf India 2016

Video: https://www.youtube.com/watch?v=V6yLT6vDB5k

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.

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 -t 5:5 -p ${PORT:-3000} -e ${RACK_ENV:-development}
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 Rails app consume in one web worker? - how much memory do you have?
20. $ free -m total used free shared buffers cached Mem: 8014 7528 486 141 291 4789 -/+ buffers/cache: 2446 5567 Swap: 511 7 504 Watch Your Memory Usage
21. $ free -m total used free shared buffers cached Mem: 8014 7528 486 141 291 4789 -/+ buffers/cache: 2446 5567 Swap: 511 7 504 Watch Your Memory Usage
22. $ free -m total used free shared buffers cached Mem: 8014 7528 486 141 291 4789 -/+ buffers/cache: 2446 5567 Swap: 511 7 504 Watch Your Memory Usage
23. $ free -m total used free shared buffers cached Mem: 8014 7528 486 141 291 4789 -/+ buffers/cache: 2446 5567 Swap: 511 7 504 Watch Your Memory Usage
24. => ☄
25. <image src="logo.png" /> 404 - Not Found The Asset Pipeline
26. # this /app/assets/images/logo.png # becomes this /public/assets/logo-a2c31b208b2a62ad9da1374497ad4db1.png The Asset Pipeline
27. # Nope <img src="logo.png" /> # Yup <%= image_tag "logo.png" %> Your Views
28. # Nope .logo background-image: url("/assets/logo.png") # Yup .logo background-image: image-url("logo.png") Your CSS
30. $ ./bin/stop-production && \ sleep 4 && \ bundle exec ./bin/start-production
32. $ 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
33. $ heroku create sushi Creating sushi... done http://sushi.herokuapp.com/ | git@heroku.com:sushi.git $ git push heroku master ----> Heroku receiving push ----> Rails app detected ----> Compiled slug size is 8.0MB http://sushi.herokuapp.com deployed to heroku
34. =>
35. $ cat config/s3.yml production: bucket: airlessbnb_production access_key_id: d6bb03e1e761dbaebb881e7a8c7a8fcc secret_access_key: 8921377d4ab6da922f5d8a12fd993ca9
36. # config/secrets.yml (.gitignore!) development: some_api_key: SOMEKEY # Usage Rails.application.secrets.some_api_key Storing Credentials
37. # Gemfile
 gem "dotenv-rails"
 # .env (.gitignore!)
 SECRET_KEY=foo
 # on heroku
 heroku config:add SECRET_KEY=foo
 # in your app
 ENV["foo"]
39. # 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"
40. # 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"
41. # 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"
42. class AddIndexForUsernameOnUsers < ActiveRecord::Migration def change add_index :users, :username end end Database Indexes
43. # 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" Database Indexes
44. # 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" Database Indexes
45. Intermission Just two more chapters in our story…
48. Long-running requests consume resources Off-load to background workers
49. # Problem User.send_sms!(message) # Solution SendSmsJob.perform_later(@user, message) Background Workers
50. class SendSmsJob < ActiveJob::Base queue_as :default def perform(user, message) SmsProvider.send(user.phone, message) end end Background Workers
51. So close… I can feel that $1B valuation just around the corner…
52. # photos_controller.rb @photos = Photo.order(:name) # index.slim - @photos do |photo| = image_tag photo.url p= photo.user.username
53. 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
54. N+1
55. # nope @photos = Photo.all # yup @photos = Photo.includes(:user) N+1 Queries
56. # 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
57. # 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
58. # Gemfile gem 'bullet', group: :development # Logs 2016-02-25 20:40:17[INFO] N+1 Query: PATH_INFO: /photos; model: Photo => associations: [users]· Add to your finder: :include => [:users] N+1 Queries
62. Running Your App In Production Keep learning
63. Thank you! Jon McCartie @jmccartie Slides: http:/ /bit.ly/rci2016