K8s: use contexthandler in standalone handler chain (#90102)

pkg/web/macaron.go

@@ -139,6 +139,17 @@ func mwFromHandler(handler Handler) Middleware {
 	}
 }
 
+// a convenience function that is provided for users of contexthandler package (standalone apiservers)
+// who have an implicit dependency on Macron in context but don't want to take a dependency on
+// router additionally
+func EmptyMacronMiddleware(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(writer http.ResponseWriter, request *http.Request) {
+		m := New()
+		c := m.createContext(writer, request)
+		next.ServeHTTP(writer, c.Req) // since c.Req has the newer context attached
+	})
+}
+
 func (m *Macaron) createContext(rw http.ResponseWriter, req *http.Request) *Context {
 	// NOTE: we have to explicitly copy the middleware chain here to avoid
 	// passing a shared slice to the *Context, which leads to racy behavior in