allow to use http middlewares

Signed-off-by: Vasiliy Tolstov <[email protected]>

http.go

@@ -375,7 +375,17 @@ func (h *httpServer) Start() error {
 		}
 	}
 
-	go http.Serve(ts, handler)
+	fn := handler
+	if h.opts.Context != nil {
+		if mwf, ok := h.opts.Context.Value(middlewareKey{}).([]func(http.Handler) http.Handler); ok && len(mwf) > 0 {
+			// wrap the handler func
+			for i := len(mwf); i > 0; i-- {
+				fn = mwf[i-1](fn)
+			}
+		}
+	}
+
+	go http.Serve(ts, fn)
 
 	go func() {
 		t := new(time.Ticker)

options.go

@@ -1,6 +1,11 @@
 package http
 
-import "context"
+import (
+	"context"
+	"net/http"
+
+	"github.com/unistack-org/micro/v3/server"
+)
 
 type rspCodeKey struct{}
 type rspCodeVal struct {
@@ -22,3 +27,9 @@ func GetRspCode(ctx context.Context) int {
 	}
 	return code
 }
+
+type middlewareKey struct{}
+
+func Middleware(mw ...func(http.Handler) http.Handler) server.Option {
+	return server.SetOption(middlewareKey{}, mw)
+}