cognito_route.go

import (
	"fmt"
	"io/ioutil"
	"log"
	"net/http"
	"strings"

	"github.com/go-chi/chi/v5"
	"github.com/go-chi/render"
)

func main() {
	...
  
	mux.Post("/", func(w http.ResponseWriter, r *http.Request) {
		b, err := ioutil.ReadAll(r.Body)
		if err != nil {
			render.JSON(w, r, http.StatusInternalServerError)
			return
		}
		defer r.Body.Close()

		out, err := route(r.Header.Get("X-Amz-Target"), b)
		if err != nil {
			log.Println(err)
			render.JSON(w, r, http.StatusInternalServerError)
			return
		}
		w.WriteHeader(http.StatusOK)
		w.Write(out)
	})

	log.Println(http.ListenAndServe(":80", mux))
}

func route(xAmzTarget string, body []byte) ([]byte, error) {
	targets := strings.Split(xAmzTarget, ".")
	if len(targets) < 2 {
		return nil, fmt.Errorf("invalid header")
	}

	switch targets[1] {
	case "AdminInitiateAuth":
		return adminInitiateAuth(body)
	case "AdminCreateUser":
		return adminCreateUser(body)
	...
	}
	return nil, fmt.Errorf("invalid operation name")
}