From 42b65377f9f5a86171577a9506de4a70923f222d Mon Sep 17 00:00:00 2001
From: Googol Lee <i@googol.im>
Date: Thu, 27 Jul 2023 16:15:24 +0200
Subject: [PATCH] Design telemetry

---
 examples/main.go | 62 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 62 insertions(+)
 create mode 100644 examples/main.go

diff --git a/examples/main.go b/examples/main.go
new file mode 100644
index 0000000..2cee488
--- /dev/null
+++ b/examples/main.go
@@ -0,0 +1,62 @@
+package main
+
+import (
+	"context"
+	"net/http"
+	"os"
+
+	"github.com/googollee/go-espresso"
+	"github.com/googollee/go-espresso/logger"
+	"github.com/googollee/go-espresso/prometheus"
+	"google.golang.org/api/tracing/v2"
+)
+
+type Data struct{}
+
+type Service struct {
+	logger logger.Logger
+	metric metric.Int
+	tracer tracing.Tracer
+}
+
+func (s *Service) HandleCreate(ctx espresso.Context[Data]) error {
+	if err := ctx.Endpoint(http.MethodPost, "/service").End(); err != nil {
+		return espresso.ErrWithStatus(http.StatusBadRequest, err)
+	}
+
+	return espresso.Procedure(ctx, s.Create)
+}
+
+func (s *Service) Create(ctx context.Context, arg int) (string, error) {
+	s.metric.Add(1)
+
+	ctx, span := s.tracer.Start(ctx)
+	defer span.End()
+
+	s.logger.Info(ctx, "in create")
+	s.logger.Debug(ctx, "input", "arg", arg)
+
+	req := http.NewRequest()
+	s.tracer.Inject(ctx, req.Header)
+	resp := http.DefaultClient.Do(req)
+
+	return "", nil
+}
+
+func main() {
+	svc := &Service{}
+
+	eng := espresso.NewEngine(
+		logger.New(os.Stderr, logger.DEBUG),
+		prometheus.New("/metrics"),
+		tracing.New("https://url"),
+	)
+
+	svc.logger = eng.Logger()
+	svc.metric = prometheus.IntGauge(eng, "calls")
+	svc.tracer = eng.Tracer()
+
+	eng.HandleAll(svc)
+
+	eng.ListenAndServe(":8080")
+}