How to run simple http server in Go

package main

import (
  "net/http"
  "log"
)

func handleGreeting(w http.ResponseWriter, r *http.Request) {
  messages, ok := r.URL.Query()["message"]
    
  if !ok || len(messages[0]) < 1 {
    log.Println("Message is missing")
    w.WriteHeader(400)
    return
  }

  message := messages[0]
  w.Write([]byte(message))
}

func main() {
  http.HandleFunc("/greet", handleGreeting)
  if err := http.ListenAndServe(":8080", nil); err != nil {
    panic(err)
  }
}

type MyRequest struct {
    Message string `json:"message"`
}

decoder := json.NewDecoder(r.Body)
var t EphemeralKeysRequest
err := decoder.Decode(&t)
if err != nil {
  panic(err)
}

message := t.Message