http/health: remove health handler (#978)

* remove health handler & example

examples/http/health/main.go

@@ -1,34 +0,0 @@
-package main
-
-import (
-	"context"
-	"errors"
-	"log"
-
-	"github.com/go-kratos/kratos/v2"
-	"github.com/go-kratos/kratos/v2/transport/http"
-	"github.com/go-kratos/kratos/v2/transport/http/health"
-)
-
-func main() {
-	handler := health.NewHandler()
-	handler.AddChecker("mysql", func(ctx context.Context) error {
-		return nil
-	})
-	handler.AddObserver("redis", func(ctx context.Context) error {
-		return errors.New("connection refused")
-	})
-
-	httpSrv := http.NewServer(http.Address(":8000"))
-	httpSrv.Handle("/healthz", handler)
-
-	app := kratos.New(
-		kratos.Name("mux"),
-		kratos.Server(
-			httpSrv,
-		),
-	)
-	if err := app.Run(); err != nil {
-		log.Println(err)
-	}
-}

transport/http/health/health.go

@@ -1,66 +0,0 @@
-package health
-
-import (
-	"context"
-	"encoding/json"
-	"net/http"
-)
-
-// CheckerFunc wraps the CheckHealth method.
-//
-// CheckHealth returns nil if the resource is healthy, or a non-nil
-// error if the resource is not healthy.  CheckHealth must be safe to
-// call from multiple goroutines.
-type CheckerFunc func(ctx context.Context) error
-
-// Handler is an HTTP handler that reports on the success of an
-// aggregate of Checkers.  The zero value is always healthy.
-type Handler struct {
-	checkers  map[string]CheckerFunc
-	observers map[string]CheckerFunc
-}
-
-// NewHandler new a health handler.
-func NewHandler() *Handler {
-	return &Handler{
-		checkers:  make(map[string]CheckerFunc),
-		observers: make(map[string]CheckerFunc),
-	}
-}
-
-// AddChecker adds a new check to the handler.
-func (h *Handler) AddChecker(name string, c CheckerFunc) {
-	h.checkers[name] = c
-}
-
-// AddObserver adds a new check to the handler but it does not fail the entire status.
-func (h *Handler) AddObserver(name string, c CheckerFunc) {
-	h.observers[name] = c
-}
-
-// ServeHTTP returns 200 if it is healthy, 500 otherwise.
-func (h *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
-	code := http.StatusOK
-	results := make(map[string]string, len(h.checkers))
-
-	for name, checker := range h.checkers {
-		if err := checker(r.Context()); err != nil {
-			code = http.StatusInternalServerError
-			results[name] = err.Error()
-		} else {
-			results[name] = "OK"
-		}
-	}
-
-	for name, checker := range h.observers {
-		if err := checker(r.Context()); err != nil {
-			results[name] = err.Error()
-		} else {
-			results[name] = "OK"
-		}
-	}
-
-	w.WriteHeader(code)
-	w.Header().Set("Content-Type", "application/json; charset=utf-8")
-	json.NewEncoder(w).Encode(results)
-}