feat: add dev server and health (#2665)

* feat: add dev server and health

* fix: fix ci

* fix: fix comment.

* feat: add enabled

* remove no need test

* feat: mv devServer to internal

* feat: default enable pprof

Co-authored-by: dylan.wang <dylan.wang@yijinin.com>

internal/devserver/config.go

@@ -0,0 +1,12 @@
+package devserver
+
+// Config is config for inner http server.
+type Config struct {
+	Enabled       bool   `json:",default=true"`
+	Host          string `json:",optional"`
+	Port          int    `json:",default=6470"`
+	MetricsPath   string `json:",default=/metrics"`
+	HealthPath    string `json:",default=/healthz"`
+	EnableMetrics bool   `json:",default=true"`
+	EnablePprof   bool   `json:",default=true"`
+}

internal/devserver/server.go

@@ -0,0 +1,86 @@
+package devserver
+
+import (
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"net/http/pprof"
+	"sync"
+
+	"github.com/felixge/fgprof"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
+
+	"github.com/zeromicro/go-zero/core/logx"
+	"github.com/zeromicro/go-zero/core/threading"
+	"github.com/zeromicro/go-zero/internal/health"
+)
+
+var (
+	once sync.Once
+)
+
+// Server is inner http server, expose some useful observability information of app.
+// For example health check, metrics and pprof.
+type Server struct {
+	config *Config
+	server *http.ServeMux
+	routes []string
+}
+
+// NewServer returns a new inner http Server.
+func NewServer(config *Config) *Server {
+	return &Server{
+		config: config,
+		server: http.NewServeMux(),
+	}
+}
+
+func (s *Server) addRoutes() {
+	// route path, routes list
+	s.handleFunc("/", func(w http.ResponseWriter, _ *http.Request) {
+		_ = json.NewEncoder(w).Encode(s.routes)
+	})
+	// health
+	s.handleFunc(s.config.HealthPath, health.CreateHttpHandler())
+
+	// metrics
+	if s.config.EnableMetrics {
+		s.handleFunc(s.config.MetricsPath, promhttp.Handler().ServeHTTP)
+	}
+	// pprof
+	if s.config.EnablePprof {
+		s.handleFunc("/debug/fgprof", fgprof.Handler().(http.HandlerFunc))
+		s.handleFunc("/debug/pprof/", pprof.Index)
+		s.handleFunc("/debug/pprof/cmdline", pprof.Cmdline)
+		s.handleFunc("/debug/pprof/profile", pprof.Profile)
+		s.handleFunc("/debug/pprof/symbol", pprof.Symbol)
+		s.handleFunc("/debug/pprof/trace", pprof.Trace)
+	}
+}
+
+func (s *Server) handleFunc(pattern string, handler http.HandlerFunc) {
+	s.server.HandleFunc(pattern, handler)
+	s.routes = append(s.routes, pattern)
+}
+
+// StartAsync start inner http server background.
+func (s *Server) StartAsync() {
+	s.addRoutes()
+	threading.GoSafe(func() {
+		addr := fmt.Sprintf("%s:%d", s.config.Host, s.config.Port)
+		logx.Infof("Starting inner http server at %s", addr)
+		if err := http.ListenAndServe(addr, s.server); err != nil {
+			logx.Error(err)
+		}
+	})
+}
+
+// StartAgent start inner http server by config.
+func StartAgent(c Config) {
+	once.Do(func() {
+		if c.Enabled {
+			s := NewServer(&c)
+			s.StartAsync()
+		}
+	})
+}