Go + microservices = Go kit

Microservices are hard, but Go and Go kit can make them easier.

1. Go + microservices = Go kit @peterbourgon · Cloud Native Con 2017 · Berlin
2. Go is a good language
 for microservices I want to convince you that and maybe Go kit will help
3. What is Go?
4. History Date: Sun, 23 Sep 2007 23:33:41 -0700
 From: "Robert Griesemer" <gri@google.com>
 To: "Rob 'Commander' Pike" <r@google.com>, ken@google.com
 Subject: prog lang discussion
 ...
 *** General:
 Starting point: C, fix some obvious flaws, remove crud, add a few missing features
 - no includes, instead: import
 - no macros (do we need something instead?)
 - ideally only one file instead of a .h and .c file, module interface 
 should be extracted automatically
 - statements: like in C, though should fix 'switch' statement
 - expressions: like in C, though with caveats (do we need ',' expressions?)
 - essentially strongly typed, but probably w/ support for runtime types
 - want arrays with bounds checking on always (except perhaps in 'unsafe mode'-see section on GC)
 - mechanism to hook up GC (I think that most code can live w/ GC, but for a true systems
 programming language there should be mode w/ full control over memory allocation)
 - support for interfaces (differentiate between concrete, or implementation types, and abstract,
 or interface types)
 - support for nested and anonymous functions/closures (don't pay if not used)
 - a simple compiler should be able to generate decent code
 - the various language mechanisms should result in predictable code
 ...
5. Go properties • Statically typed • Compiled — fast! • Native binaries • Garbage collected • Looks like C • Big standard library • Baked-in concurrency
6. Go IMO • A breath of fresh air from “kitchen sink” languages — cf. Scala • Simple, orthogonal features that aren't surprising — cf. Node • Efficient by default — cf. Python, Ruby • Predictable runtime behavior — cf. JVM languages • Familiar heritage, syntax, and paradigm — cf. Haskell, Elixir
7. “Simple”
8. “No magic”
9. https://talks.golang.org/2012/splash.article
11. Mindshare
12. Mindshare
13. Microservices
15. Microservices solve organizational problems
 ~
 Microservices cause
 technical problems
16. Problems solved • Team is too large to work effectively on shared codebase • Teams are blocked on other teams, can't make progress • Communication overhead becomes gigantic • Product velocity stalled
17. Problems caused • Need well-defined business domains for stable APIs • No more shared DB — distributed transactions? • Testing becomes really hard • Require dev/ops culture: devs deploy & operate their work • Job (service) scheduling — manually works, for a while...
18. Problems caused • Addressability i.e. service discovery • Monitoring and instrumentation — tail -f? Nagios & New Relic? Ha! • Distributed tracing? • Build pipelines?? • Security???
23. Concerns for a single service, Sean Treadway, SoundCloud
24. Enter Go kit
25. Initial goals • A standard library for microservices • Something like Finagle for Go • Adapters, bindings, etc. to common infrastructure components • Play nice in your existing, heterogeneous infrastructure • Structure to tame the beast of incidental complexity
26. Current goals • Mostly the same • Even less opinionated about infrastructure than anticipated • More opinionated about application architecture than anticipated
27. Non-goals • Messaging patterns other than RPC • Requiring specific bits of infrastructure or tooling to work • Acting as an all-in service framework • Re-implementing existing, good solutions to problems
28. Comparisons • Micro (Go) — very opinionated, all-in, framework-ish • Finagle (Scala) — original inspiration, lower-level than Go kit • Spring Boot (Java) — similar abstractions, far more magical • Tokio (Rust) — explicitly a clone of Finagle, lower-level than Go kit
29. I don’t care if you use Go kit; I do care if you use Go I really want to emphasize
30. Example service
31. type AddService interface { Sum(a, b int) int Concat(a, b string) string }
32. type AddService interface { Sum(a, b int) (int, error) Concat(a, b string) (string, error) }
33. Naïve first draft
34. type basicService struct{} func (s basicService) Sum(a, b int) (int, error) { return a + b, nil } func (s basicService) Concat(a, b string) (string, error) { return a + b, nil } Core Business Logic
35. Transport Core Business Logic
36. func (s basicService) ServeHTTP(w http.ResponseWriter, r *http.Request) { switch r.URL.Path { case "/sum":
37. func (s basicService) ServeHTTP(w http.ResponseWriter, r *http.Request) { switch r.URL.Path { case "/sum": var req struct { A int `json:"a"` B int `json:"b"` } if err := json.NewDecoder(r.Body).Decode(&req); err != nil { http.Error(w, err.Error(), http.StatusBadRequest) return }
38. func (s basicService) ServeHTTP(w http.ResponseWriter, r *http.Request) { switch r.URL.Path { case "/sum": var req struct { A int `json:"a"` B int `json:"b"` } if err := json.NewDecoder(r.Body).Decode(&req); err != nil { http.Error(w, err.Error(), http.StatusBadRequest) return } v, err := s.Sum(req.A, req.B) if err != nil { http.Error(w, err.Error(), http.StatusInternalServerError) return }
39. func (s basicService) ServeHTTP(w http.ResponseWriter, r *http.Request) { switch r.URL.Path { case "/sum": var req struct { A int `json:"a"` B int `json:"b"` } if err := json.NewDecoder(r.Body).Decode(&req); err != nil { http.Error(w, err.Error(), http.StatusBadRequest) return } v, err := s.Sum(req.A, req.B) if err != nil { http.Error(w, err.Error(), http.StatusInternalServerError) return } w.Header().Set("Content-Type", "application/json; charset=utf-8") json.NewEncoder(w).Encode(map[string]int{"v": v})
40. case "/concat":
41. case "/concat": var req struct { A string `json:"a"` B string `json:"b"` } if err := json.NewDecoder(r.Body).Decode(&req); err != nil { http.Error(w, err.Error(), http.StatusBadRequest) return }
42. case "/concat": var req struct { A string `json:"a"` B string `json:"b"` } if err := json.NewDecoder(r.Body).Decode(&req); err != nil { http.Error(w, err.Error(), http.StatusBadRequest) return } v, err := s.Concat(req.A, req.B) if err != nil { http.Error(w, err.Error(), http.StatusInternalServerError) return }
43. case "/concat": var req struct { A string `json:"a"` B string `json:"b"` } if err := json.NewDecoder(r.Body).Decode(&req); err != nil { http.Error(w, err.Error(), http.StatusBadRequest) return } v, err := s.Concat(req.A, req.B) if err != nil { http.Error(w, err.Error(), http.StatusInternalServerError) return } w.Header().Set("Content-Type", "application/json; charset=utf-8") json.NewEncoder(w).Encode(map[string]string{"v": v})
44. Transport Core Business Logic App Logging
45. if err := json.NewDecoder(r.Body).Decode(&req); err != nil { code := http.StatusBadRequest log.Printf("%s: %s: %d", r.RemoteAddr, r.URL, code) http.Error(w, err.Error(), code) return } v, err := s.Sum(req.A, req.B) if err != nil { code := http.StatusInternalServerError log.Printf("%s: %s: %d", r.RemoteAddr, r.URL, code) http.Error(w, err.Error(), code) return } w.Header().Set("Content-Type", "application/json; charset=utf-8") json.NewEncoder(w).Encode(map[string]int{"v": v}) log.Printf("%s: %s: %d", r.RemoteAddr, r.URL, 200)
46. type basicService struct{} func (s basicService) Sum(a, b int) (v int, err error) { defer func() { log.Printf(“Sum(%d,%d)=(%d,%v)”, a, b, v, err) }() return a + b, nil } func (s basicService) Concat(a, b string) (string, error) { defer func() { log.Printf(“Concat(%q,%q)=(%q,%v)”, a, b, v, err) }() return a + b, nil }
47. Transport Core Business Logic App Logging Metrics
48. if err := json.NewDecoder(r.Body).Decode(&req); err != nil { code := http.StatusBadRequest log.Printf("%s: %s: %d", r.RemoteAddr, r.URL, code) errorCount.Add(1) http.Error(w, err.Error(), code) return } v, err := s.Sum(req.A, req.B) if err != nil { code := http.StatusInternalServerError log.Printf("%s: %s: %d", r.RemoteAddr, r.URL, code) errorCount.Add(1) http.Error(w, err.Error(), code) return } w.Header().Set("Content-Type", "application/json; charset=utf-8") json.NewEncoder(w).Encode(map[string]int{"v": v}) log.Printf("%s: %s: %d", r.RemoteAddr, r.URL, 200)
 successCount.Add(1)
49. Transport Core Business Logic App Logging Metrics Tracing Circuit Breaking Rate Limiting Audit Logging Service Discovery Deploy Strategy Contract Testing Alerting Caching Strategy Security Service Registry :( :( :( ;( :( :(
50. The onion model
51. Transport Operational Metrics Balancing, Limiting, Safety Business Analytics Application Logging Service Metrics Business Logic Service Endpoint Transport
52. http://fideloper.com/hexagonal-architecture
53. The central rule of The Clean Architecture is the Dependency Rule, which says source code dependencies can only point inwards. — http://appliedgo.net/di
54. Service layer
55. type Service interface { Sum(ctx context.Context, a, b int) (int, error) Concat(ctx context.Context, a, b string) (string, error) }
56. type Service interface { Sum(ctx context.Context, a, b int) (int, error) Concat(ctx context.Context, a, b string) (string, error) } type basicService struct{}
57. type Service interface { Sum(ctx context.Context, a, b int) (int, error) Concat(ctx context.Context, a, b string) (string, error) } type basicService struct{} func (s basicService) Sum(_ context.Context, a, b int) (int, error) { if a == 0 && b == 0 { return 0, ErrTwoZeroes } if (b > 0 && a > (intMax-b)) || (b < 0 && a < (intMin-b)) { return 0, ErrIntOverflow } return a + b, nil }
58. type Service interface { Sum(ctx context.Context, a, b int) (int, error) Concat(ctx context.Context, a, b string) (string, error) } type basicService struct{} func (s basicService) Sum(_ context.Context, a, b int) (int, error) { if a == 0 && b == 0 { return 0, ErrTwoZeroes } if (b > 0 && a > (intMax-b)) || (b < 0 && a < (intMin-b)) { return 0, ErrIntOverflow } return a + b, nil } func (s basicService) Concat(_ context.Context, a, b string) (string, error) { if len(a)+len(b) > maxLen { return "", ErrMaxSizeExceeded } return a+b, nil }
59. type Middleware func(Service) Service
60. type Middleware func(Service) Service type loggingMiddleware struct { logger log.Logger next Service }
61. type Middleware func(Service) Service type loggingMiddleware struct { logger log.Logger next Service } func NewLoggingMiddleware(logger log.Logger) Middleware { return func(next Service) Service { return loggingMiddleware{logger, next} } }
62. type Middleware func(Service) Service type loggingMiddleware struct { logger log.Logger next Service } func NewLoggingMiddleware(logger log.Logger) Middleware { return func(next Service) Service { return loggingMiddleware{logger, next} } } func (mw loggingMiddleware) Sum(ctx context.Context, a, b int) (v int, err error) { defer func() { mw.logger.Log("method", "Sum", "a", a, "b", b, "v", v, "err", err) }() return mw.next.Sum(ctx, a, b) } // Concat is the same
63. type Middleware func(Service) Service
64. type Middleware func(Service) Service type instrumentingMiddleware struct { ints metrics.Counter chars metrics.Counter next Service }
65. type Middleware func(Service) Service type instrumentingMiddleware struct { ints metrics.Counter chars metrics.Counter next Service } func NewInstrumentingMiddleware(ints, chars metrics.Counter) Middleware { return func(next Service) Service { return instrumentingMiddleware{ ints: ints, chars: chars, next: next, } } }
66. type Middleware func(Service) Service type instrumentingMiddleware struct { ints metrics.Counter chars metrics.Counter next Service } func NewInstrumentingMiddleware(ints, chars metrics.Counter) Middleware { return func(next Service) Service { return instrumentingMiddleware{ ints: ints, chars: chars, next: next, } } } func (mw instrumentingMiddleware) Sum(ctx context.Context, a, b int) (int, error) { v, err := mw.next.Sum(ctx, a, b) mw.ints.Add(v) return v, err }
67. And a lot more...!
68. Endpoint layer
69. type Endpoint func(req) resp
70. type Endpoint func(req interface{}) (resp interface{})
71. type Endpoint func(ctx context.Context, req interface{}) (resp interface{}, err error)
72. type Endpoint func(ctx context.Context, req interface{}) (resp interface{}, err error) func MakeSumEndpoint(s Service) Endpoint { return func(ctx context.Context, req interface{}) (resp interface{}, err error) { request := req.(SumRequest) v, err := s.Sum(ctx, request.A, request.B) return SumResponse{V: v, Err: err}, nil } }
73. type Endpoint func(ctx context.Context, req interface{}) (resp interface{}, err error) func MakeSumEndpoint(s Service) Endpoint { return func(ctx context.Context, req interface{}) (resp interface{}, err error) { request := req.(SumRequest) v, err := s.Sum(ctx, request.A, request.B) return SumResponse{V: v, Err: err}, nil } } type SumRequest struct { A, B int } type SumResponse struct { V int Err error }
74. type Middleware func(Endpoint) Endpoint
75. type Middleware func(Endpoint) Endpoint func NewCircuitBreakingMiddleware(cb *gobreaker.CircuitBreaker) Middleware { return func(next Endpoint) Endpoint { return func(ctx context.Context, req interface{}) (interface{}, error) { return cb.Execute(func() (interface{}, error) { return next(ctx, req) }) } } }
76. type Middleware func(Endpoint) Endpoint func NewCircuitBreakingMiddleware(cb *gobreaker.CircuitBreaker) Middleware { return func(next Endpoint) Endpoint { return func(ctx context.Context, req interface{}) (interface{}, error) { return cb.Execute(func() (interface{}, error) { return next(ctx, req) }) } } } func NewThrottlingMiddleware(b *ratelimit.Bucket) Middleware { return func(next Endpoint) Endpoint { return func(ctx context.Context, req interface{}) (interface{}, error) { time.Sleep(tb.Take(1)) return next(ctx, request) } } }
77. Transport layer
78. Endpoint HTTP, gRPC, etc. Decode
 Request Encode
 Response
79. HTTP func NewServer( e endpoint.Endpoint, dec DecodeRequestFunc, enc EncodeResponseFunc, options ...ServerOption, ) *Server { // ...
 } func (s Server) ServeHTTP(w http.ResponseWriter, r *http.Request) { request, err := s.dec(ctx, r) if err != nil { return }
 response, err := s.e(ctx, request) if err != nil { return } if err := s.enc(ctx, w, response); err != nil { return } }
80. gRPC func NewServer( e endpoint.Endpoint, dec DecodeRequestFunc, enc EncodeResponseFunc, options ...ServerOption, ) *Server { // ...
 } func (s Server) ServeGRPC(ctx Context, req interface{}) (Context, interface{}, request, err := s.dec(ctx, req) if err != nil { s.logger.Log("err", err) return ctx, nil, err } response, err := s.e(ctx, request) if err != nil { return ctx, nil, err } grpcResp, err := s.enc(ctx, response) if err != nil { return ctx, nil, err } return ctx, grpcResp, nil }
81. HTTP Mux HTTP Server HTTP Server CB CB RL RL Concat Sum Logging Service
82. HTTP Mux gRPC Mux gRPC Server gRPC Server HTTP Server HTTP Server CB CB RL RL Concat Sum Logging Service
83. Simple & non-magical We embrace and extend Go’s philosophy, to be in service to software engineering in the large * *
84. Maintainability Optimize for above all else!
85. Integration with the
 Cloud Native stack
86. Prometheus type metricsMiddleware struct { ints metrics.Counter chars metrics.Counter next Service } func (mw metricsMiddleware) Sum(ctx context.Context, a, b int) (int, error) { v, err := mw.next.Sum(ctx, a, b) mw.ints.Add(v) return v, err } func (mw metricsMiddleware) Concat(ctx context.Context, a, b string) (string, error) { v, err := mw.next.Concat(ctx, a, b) mw.chars.Add(len(v)) return v, err }
87. OpenTracing & Zipkin Transport Operational Metrics Balancing, Limiting, Safety Business Analytics Application Logging Service Metrics Business Logic Extract Inject Annotate & Collect
88. OpenTracing & Zipkin Extract Inject Annotate & Collect
89. Demo
90. Where to Go from here?
91. invite.slack.golangbridge.org appliedgo.net gobyexample.com gokit.io
92. gophercon.com
93. Thanks @peterbourgon · Cloud Native Con 2017 · Berlin