Fighting Legacy Codebases with GraphQL and Rails

GraphQL is one of the hottest technologies of the past year or two. Still, very little is talked about GraphQL outside of the realm of front-end applications.

We used a different approach at IFTTT and applied GraphQL as an integration layer for different backends and client apps.

This talk goes beyond the basic configuration of a GraphQL endpoint with Rails. I’ll cover topics such ActiveRecord Query optimization, performance monitoring, batching and share some of the challenges we ran into while building a GraphQL API that serves over 10 thousand queries per minute.

Transcript

1. Rescuing legacy codebases with GraphQL and Rails @nettofarah
2. Netto Farah @nettofarah !"
3. Conference speakers are professional enthusiasts Take this with a grain of salt
5. Context • Website, iOS app, Android app • Seasoned Rails 3 codebase
6. Technical Challenge • Build an entirely new website and mobile apps • Iterate fast (9 months deadline)
7. We knew we needed to make some changes
8. Majestic Monoliths vs Micro-services
9. Not a binary decision
10. A hybrid approach: Rich API + specific clients
11. Challenges with Traditional APIs
12. Multiple use cases
13. with different access patterns
14. Documentation and Conventions
15. [%,",&..'] => ✅ )
16. ) [!] => ask me later…
17. GraphQL a language specification for 
 defining and querying APIs
18. Describe your data with TYPES
19. type Rubygem { name: String downloads: Int versions: [Version] }
20. Load just what you need
21. query { rubygems {
 name downloads } }
22. You can even load multiple entities at once
23. query { rubygems {
 name, downloads } current_user { login, email } }
24. Get predictable results
25. { "data": { "rubygem": { "name": "rails", "downloads": 89321853 }, “current_user": { "login": "nettofarah", "email": “nettofarah@gmail.com" } } }
26. GraphQL focuses on the clients
27. GraphQL + Ruby = ❤
28. Demo time!
29. RubyGems API Rubygem Version Dependency has_many has_many
30. RubyGems API - use cases • list all available rubygems • search one specific rubygem by name
31. Let’s see some code! http://bit.ly/gql-demo
32. We built a GraphQL API on top of our data model
33. GraphQL API as an integration layer for multiple (not so micro) services and front-ends
34. GraphQL API ☁ A P I 
 G
 A
 T E
 W
 A Y Service A Service B Service C
35. GraphQL API ⛈ A P I 
 G
 A
 T E
 W
 A Y Service A Service B Service C
36. GraphQL in production
37. What happened to semantic status codes?
38. N+1 queries
39. github.com/nettofarah/graphql-query-resolver
40. Monitoring and Errors
44. http://bit.ly/gql-rb-nr
45. Where to go next? • graphql.org • graphql.slack.com (#ruby - I hang out there) • https://github.com/rmosolgo/graphql-ruby
46. @nettofarah nettofarah@gmail.com