Building a Bank with Go - QCon London March 2017

Traditionally applications have been built as monoliths; single applications which become larger and more complex over time, which limit our ability to react to change. An example of this is the banking industry where mergers and acquisitions between banks have lead to a patchwork of different systems & technologies that cost billions of dollars per year to maintain. As a result, the pace of innovation in the banking industry has slowed to a crawl. At Monzo we're building a new kind of bank backed by a microservice platform written in Go. In this talk we'll look at why Go is perfectly suited to this style of architecture, the language features that make it particularly attractive to high volume, low latency, distributed applications, and how easy it is to adopt into existing systems and organisations.

Transcript

1. Building a Bank with Go Matt Heath, Monzo
2. Hi, I’m Matt @mattheath
5. monoliths traditional dev
6. A UK banking licence is authorised by the PRA and regulated by the PRA and FCA1, allowing deposit- taking and balance sheet lending. Once granted, it allows firms to passport across Europe, accessing This is followed by a “mobilisation” phase during which final capital is raised and IT systems are completed, before launching to the public. We received a UK banking licence in August 2016! FEB 2015 JAN 2016 JAN 2017 MAR FEB FEB APR MAR MAR APR MAY JUN JUL MAY APR JUN MAY JUL JUN AUG JUL SEP AUG NOV SEP DEC NOV DEC PRE APPLICATION APPLICATION MOBILISATION LAUNCH LICENCE WITH RESTRICTIONS 50K MAX DEPOSIT WE ARE HERE
15. ?
16. Application
17. Application Database
18. Application Database
19. Application Databases
20. Application Databases Search
21. Application Databases Search Caching
22. Application Databases Search Caching CAT GIFS
23. ALL HAIL THE MONOLITH
25. Application Databases Search Caching CAT GIFS
26. APPLICATION Application
29. Single Responsibility Principle
30. Bounded Context
31. Well defined Interfaces
33. Why Go? Memory Managed Statically Typed Excellent Concurrency Perfect for simple, small, network services
34. Lightweight Concurrency
35. Goroutines
36. // Blocking function call handleRequest()
37. // Function runs concurrently go handleRequest()
38. package main func main() { go handleRequest() // … }
39. package main func main() { go handleRequest() // … } main
40. package main func main() { go handleRequest() // … } handleRequest main
41. "Do not communicate by sharing memory; instead, share memory by communicating." - Effective Go
42. Channels
47. Simplicity
48. Static Linking Stdlib etc
49. 0 40 80 160 120 Feb 2015 Mar 2017 200 Number of services
52. monzo/typhon
53. Service Service
54. Service Service Transport
55. Service Service Transport Service Service
56. Service Service Transport Service Service Client library Server library
57. Service Service Service Service HTTP HTTP
58. Service Discovery Load Balancing Timeouts and Expirations Retries Rate Limiting Connection Pooling Circuit Breaking Failure Detection Metrics and Tracing Interrupts Context Propagation
59. Service Service Service Service HTTP HTTP ?
60. Service Service Service Service HTTP HTTP linkerd
61. Service Discovery Load Balancing Timeouts and Expirations Retries Rate Limiting Connection Pooling Circuit Breaking Failure Detection Metrics and Tracing Interrupts Context Propagation
62. Load Balancer
63. Load Balancer HTTP API & Routing Layer
64. Load Balancer HTTP API & Routing Layer API
 Service
66. /webhooks —-> Webhook API
67. Load Balancer HTTP API & Routing Layer Webhook
 API
68. Auth
 Service Webhook
 Service Load Balancer HTTP API & Routing Layer Webhook
 API
69. Auth
 Service Webhook
 Service Load Balancer HTTP API & Routing Layer Webhook
 API Database
70. Database Auth
 Service Webhook
 Service Load Balancer HTTP API & Routing Layer Webhook
 API Database
71. External Provider Database Auth
 Service Webhook
 Service Load Balancer HTTP API & Routing Layer Webhook
 API Database
72. type Service func(req Request) Response
73. router.GET("/", List) router.POST("/", Register) router.DELETE("/:id", Deregister)
74. Making our service reliable
75. + = ❤
77. Webhook
 Service Webhook
 Service Webhook
 Service Load Balancer HTTP API & Routing Layer Webhook
 API
78. Webhook
 Service Webhook
 Service Webhook
 Service Load Balancer HTTP API & Routing Layer Webhook
 API
79. Webhook
 Service Webhook
 Service Webhook
 Service Webhook
 Service Load Balancer HTTP API & Routing Layer Webhook
 API
80. Webhook
 Service Webhook
 Service Webhook
 Service Webhook
 Service Load Balancer HTTP API & Routing Layer Webhook
 API Slow or
 Errors
81. Event Driven Architecture
82. Service A Service B Load Balancer HTTP API & Routing Layer API Service
83. API Service Service A Service B Load Balancer HTTP API & Routing Layer
84. API Service Service A Service B Load Balancer HTTP API & Routing Layer
85. API Service Service A Service B Load Balancer HTTP API & Routing Layer Service C Service D Service E
86. Context Propagation
87. api api api.customer api.customer service.customer service.customer
88. api api api.customer api.customer service.customer service.customer
89. 8096820c-3b7b-47ec-bce6-1c239252ab40
90. api api api.customer api.customer service.customer service.customer
91. api api api.customer api.customer service.customer service.customer
92. package context type Context interface { Deadline() (deadline time.Time, ok bool) Done() <-chan struct{} Err() error Value(key interface{}) interface{} }
93. package context type Context interface { Deadline() (deadline time.Time, ok bool) Done() <-chan struct{} Err() error Value(key interface{}) interface{} }
94. package context type Context interface { Deadline() (deadline time.Time, ok bool) Done() <-chan struct{} Err() error Value(key interface{}) interface{} }
95. api api api.customer api.customer service.customer service.customer
96. api api api.customer api.customer service.customer service.customer SEND RECV SEND RECV RECV SEND RECV SEND
97. api api.customer service.customer SEND RECV SEND RECV RECV SEND RECV SEND phosphor
99. API card-api card-processing cards transactions balance transaction-enrichment merchant feed-generator feed apns API card-api card-processing cards transactions balance transaction-enrichment merchant feed-generator feed apns
100. API card-api card-processing cards transactions balance transaction-enrichment merchant feed-generator feed apns API card-api card-processing cards transactions balance transaction-enrichment merchant feed-generator feed apns
101. API card-api card-processing cards transactions balance transaction-enrichment merchant feed-generator feed apns API card-api card-processing cards transactions balance transaction-enrichment merchant feed-generator feed apns
102. API card-api card-processing cards transactions balance transaction-enrichment merchant feed-generator feed apns API card-api card-processing cards transactions balance transaction-enrichment merchant feed-generator feed apns
103. API card-api card-processing cards transactions balance transaction-enrichment merchant feed-generator feed apns API card-api card-processing cards transactions balance transaction-enrichment merchant feed-generator feed apns
105. API card-api card-processing cards transactions balance transaction-enrichment merchant feed-generator feed apns API card-api card-processing cards transactions balance transaction-enrichment merchant feed-generator feed apns
108. Perfect for
 microservice architectures
109. Concurrency:
 Goroutines Channels
110. Small Simple Easy
111. Thanks! @mattheath @monzo