main.go

func main() {

        current_ip := currentExternalIp()

        resp, err := client.ListResourceRecordSets(&route53.ListResourceRecordSetsInput{
                HostedZoneId: aws.String(zone_id),
        })

        if err != nil {
                panic(err)
        }

        for _, record := range resp.ResourceRecordSets {
                if *record.Type == "A" && *record.Name == domain {
                        if strings.Compare(*record.ResourceRecords[0].Value, current_ip) != 0 {
                                log.Printf("current set ip %s", *record.ResourceRecords[0].Value)
                                log.Printf("current ip %s", current_ip)

                                updateRecordValue(current_ip)
                        } else {
                                log.Println("no update")
                        }
                }
        }

}

func currentExternalIp() (ip string) {
        resp, err := http.Get("http://myexternalip.com/raw")
        if err != nil {
                log.Fatalf("Get ExterlIP Error %s", err.Error())
        }
        defer resp.Body.Close()

        body, err := ioutil.ReadAll(resp.Body)
        if err != nil {
                log.Fatalf("Get ExterlIP Error %s", err.Error())
        }

        ip = strings.TrimSpace(string(body))

        return ip
}

func updateRecordValue(current_ip string) {
        resource_record := &route53.ResourceRecord{Value: aws.String(current_ip)}
        resource_records := []*route53.ResourceRecord{resource_record}

        resource_record_set := &route53.ResourceRecordSet{
                Name:            aws.String(domain),
                TTL:             aws.Int64(60),
                Type:            aws.String("A"),
                ResourceRecords: resource_records,
        }
        change := &route53.Change{
                Action:            aws.String("UPSERT"),
                ResourceRecordSet: resource_record_set,
        }
        change_batch := &route53.ChangeBatch{
                Changes: []*route53.Change{change},
        }
        change_resource_record_set_input := &route53.ChangeResourceRecordSetsInput{
                HostedZoneId: aws.String(zone_id),
                ChangeBatch:  change_batch,
        }

        response, err := client.ChangeResourceRecordSets(change_resource_record_set_input)
        if err != nil {
                log.Fatalf("Route53 Record Update Error %s", err.Error())
        }

        fmt.Printf("%#v", response)
}