Zipkin : Golang 微服务全链路监控（三）

Zipkin : Golang 微服务全链路监控（三）

Golang 微服务全链路监控实现

1. broker-service -> auth-service -> postgres db
2. zipkin 监控：需代码入侵

使用 zipkin 库的 serverMiddleware，其通过 Http 跟踪（trace）链路。若要连接数据库，需传 tracer

zipkinhttp "github.com/openzipkin/zipkin-go/middleware/http"

一、auth-service

1. 通过 Http 传递 span
   main.go

package mainimport ("database/sql""log""net/http""os""time""tracing/auth-service/data"zipkinhttp "github.com/openzipkin/zipkin-go/middleware/http"_ "github.com/jackc/pgconn"_ "github.com/jackc/pgx/v4"_ "github.com/jackc/pgx/v4/stdlib"
)const webPort = "80"const (// Our service name.serviceName = "authentication"// Host + port of our service.hostPort = "localhost:8090"// Endpoint to send Zipkin spans to.zipkinHTTPEndpoint = "http://localhost:9411/api/v2/spans"
)var counts int64type Config struct {DB     *sql.DBModels data.Models
}func main() {log.Println("Starting authentication service: ", webPort)//connect to DBconn := connectToDB()if conn == nil {log.Panic("Can't connect to Postgres!")}//setup configapp := Config{DB:     conn,Models: data.New(conn),}tracer := GetTracer(serviceName, hostPort, zipkinHTTPEndpoint)// create global zipkin http server middlewareserverMiddleware := zipkinhttp.NewServerMiddleware(tracer, zipkinhttp.TagResponseSize(true),)// create global zipkin traced http clientclient, err := zipkinhttp.NewClient(tracer, zipkinhttp.ClientTrace(true))if err != nil {log.Fatalf("unable to create client: %+v\n", err)}// initialize routerrouter := http.NewServeMux()// if need to trace db, transfer tracerrouter.HandleFunc("/authenticate", app.Authenticate(client, tracer))if err = http.ListenAndServe(hostPort, serverMiddleware(router)); err != nil {log.Panic(err)}
}

2. auth 服务
   handler.go

package mainimport ("errors""fmt""log""net/http""github.com/openzipkin/zipkin-go"zipkinhttp "github.com/openzipkin/zipkin-go/middleware/http"
)type AuthPayload struct {Email    string `json:"email"`Password string `json:"password"`
}func (app *Config) Authenticate(client *zipkinhttp.Client, tracer *zipkin.Tracer) http.HandlerFunc {return func(w http.ResponseWriter, r *http.Request) {log.Printf("auth service called with method: %s\n", r.Method)var requestPayload AuthPayloadvar payload jsonResponsepayload.Error = truepayload.Message = "Authentication failed!"err := app.readJSON(w, r, &requestPayload)if err != nil {app.errorJSON(w, err)return}log.Println("requestPayload:", requestPayload)// retrieve span from context (created by zipkinhttp server middleware)span := zipkin.SpanFromContext(r.Context())defer span.Finish()span.Tag("event", "authenticate")ctx := zipkin.NewContext(r.Context(), span)// transfer tracer to dbuser, err := app.Models.User.GetByEmail(ctx, tracer, requestPayload.Email)if err != nil {app.errorJSON(w, errors.New("invalid credentials"), http.StatusBadGateway)span.Tag("Error: ", err.Error())return}log.Println("user:", user)valid, err := user.PasswordMatches(requestPayload.Password)if err != nil || !valid {app.errorJSON(w, errors.New("invalid credentials"), http.StatusBadGateway)span.Tag("Error: ", err.Error())return}payload = jsonResponse{Error:   false,Message: fmt.Sprintf("Logged in user %s", user.Email),Data:    user,}log.Println("auth response: ", payload)app.writeJSON(w, http.StatusOK, payload)}
}

二、models.go

func (u *User) GetByEmail(c context.Context, tracer *zipkin.Tracer, email string) (*User, error) {// tracer 通过 context，获取 spanspan, _ := tracer.StartSpanFromContext(c, "GetByEmail")defer span.Finish()span.Tag("query", "select id, email, first_name, last_name, password, user_active, created_at, updated_at from users where email = "+email)ctx, cancel := context.WithTimeout(context.Background(), dbTimeout)defer cancel()query := `select id, email, first_name, last_name, password, user_active, created_at, updated_at from users where email = $1`var user Userrow := db.QueryRowContext(ctx, query, email)err := row.Scan(&user.ID,&user.Email,&user.FirstName,&user.LastName,&user.Password,&user.Active,&user.CreatedAt,&user.UpdatedAt,)if err != nil {log.Println("Error GetByEmail: ", err)span.Tag("Error GetByEmail: ", err.Error())return nil, err}return &user, nil
}

三、说明

完整代码参考：

1. Zipkin : Golang 微服务全链路监控（一）
2. Zipkin : Golang 微服务全链路监控（二）