forked from PacktPublishing/Mastering-Distributed-Tracing
/
hello.go
81 lines (68 loc) · 2.07 KB
/
hello.go
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package main
import (
"context"
"encoding/json"
"log"
"net/http"
"net/url"
"strings"
opentracing "github.com/opentracing/opentracing-go"
otlog "github.com/opentracing/opentracing-go/log"
"github.com/PacktPublishing/Mastering-Distributed-Tracing/Chapter04/go/lib/http"
"github.com/PacktPublishing/Mastering-Distributed-Tracing/Chapter04/go/lib/model"
"github.com/PacktPublishing/Mastering-Distributed-Tracing/Chapter04/go/lib/tracing"
)
func main() {
tracer, closer := tracing.Init("go-4-hello")
defer closer.Close()
opentracing.SetGlobalTracer(tracer)
http.HandleFunc("/sayHello/", handleSayHello)
log.Print("Listening on http://localhost:8080/")
log.Fatal(http.ListenAndServe(":8080", nil))
}
func handleSayHello(w http.ResponseWriter, r *http.Request) {
span := opentracing.GlobalTracer().StartSpan("say-hello")
defer span.Finish()
ctx := opentracing.ContextWithSpan(r.Context(), span)
name := strings.TrimPrefix(r.URL.Path, "/sayHello/")
greeting, err := SayHello(ctx, name)
if err != nil {
span.SetTag("error", true)
span.LogFields(otlog.Error(err))
http.Error(w, err.Error(), http.StatusInternalServerError)
return
}
span.SetTag("response", greeting)
w.Write([]byte(greeting))
}
// SayHello creates a greeting for the named person.
func SayHello(ctx context.Context, name string) (string, error) {
person, err := getPerson(ctx, name)
if err != nil {
return "", err
}
return formatGreeting(ctx, person)
}
func getPerson(ctx context.Context, name string) (*model.Person, error) {
res, err := xhttp.Get("http://localhost:8081/getPerson/" + name)
if err != nil {
return nil, err
}
var person model.Person
if err := json.Unmarshal(res, &person); err != nil {
return nil, err
}
return &person, nil
}
func formatGreeting(ctx context.Context, person *model.Person) (string, error) {
v := url.Values{}
v.Set("name", person.Name)
v.Set("title", person.Title)
v.Set("description", person.Description)
url := "http://localhost:8082/formatGreeting?" + v.Encode()
res, err := xhttp.Get(url)
if err != nil {
return "", err
}
return string(res), nil
}