Golang DNS server with multiple A/SRV records

main.go

package main

import (
	"fmt"
	"log"

	"github.com/miekg/dns"
)

// adapted from https://gist.github.com/walm/0d67b4fb2d5daf3edd4fad3e13b162cb
// to support multiple A records (different IPs) and multiple SRV records (same host, different ports).

// dig @localhost -p 5353 test.service
var records = map[string][]string{
	"test.service.": {
		"192.168.0.2",
		"192.168.0.3",
		"192.168.0.4",
		"192.168.0.5",
	},
}

// dig @localhost -p 5353 _api._tcp.localhost SRV
var srvRecords = map[string][]string{
	"_api._tcp.localhost.": {
		"10 5 8080 localhost",
		"10 5 8081 localhost",
		"10 5 8082 localhost",
		"10 5 8083 localhost",
	},
}

func parseQuery(m *dns.Msg) {
	for _, q := range m.Question {
		log.Printf("Query for %s\n", q.Name)

		switch q.Qtype {
		case dns.TypeA:
			ips := records[q.Name]
			if len(ips) > 0 {
				for _, ip := range ips {
					rr, err := dns.NewRR(fmt.Sprintf("%s A %s", q.Name, ip))
					if err == nil {
						m.Answer = append(m.Answer, rr)
					}
				}
			}
		case dns.TypeSRV:
			ips := srvRecords[q.Name]
			if len(ips) > 0 {
				for _, ip := range ips {
					rr, err := dns.NewRR(fmt.Sprintf("%s SRV %s", q.Name, ip))
					if err == nil {
						m.Answer = append(m.Answer, rr)
					}
				}
			}
		}
	}
}

func handleDnsRequest(w dns.ResponseWriter, r *dns.Msg) {
	m := new(dns.Msg)
	m.SetReply(r)
	m.Compress = false

	switch r.Opcode {
	case dns.OpcodeQuery:
		parseQuery(m)
	}

	w.WriteMsg(m)
}

func main() {
	// attach request handler func
	dns.HandleFunc(".", handleDnsRequest)

	// start server
	server := &dns.Server{Addr: ":5353", Net: "udp"}
	log.Printf("Starting at %s\n", server.Addr)

	err := server.ListenAndServe()
	if err != nil {
		log.Fatalf("Failed to start server: %s\n ", err.Error())
	}

	defer server.Shutdown()
}

Please use port 53 and add DNS 127.0.0.7 to the system.Then you can try nslookup or curl.