Upgrade the application to Systemd service

dyndns.service

@@ -0,0 +1,23 @@
+[Unit]
+Description=DynDNS
+After=network.target network-online.target
+StartLimitIntervalSec=60s
+StartLimitBurst=3
+
+[Service]
+Environment=CF_token=''
+Environment=Domain=''
+Environment=Subdomain=''
+Environment=CF_proxy_disabled=1
+ExecStart=/usr/local/bin/DynDNS
+Type=simple
+User=root
+Group=root
+Restart=always
+RestartSec=5
+SyslogIdentifier=DynDNS
+StandardOutput=journal
+StandardError=journal
+
+[Install]
+WantedBy=multi-user.target

main.go

@@ -3,53 +3,67 @@ package main
 import (
 	"encoding/json"
 	"errors"
+	"flag"
 	"fmt"
 	"github.com/praveenprem/dyndns/cloudflare"
 	"log"
 	"net/http"
 	"os"
+	"os/signal"
+	"syscall"
+	"time"
 )
 
 type ipv4 struct {
 	IP string `json:"ip"`
 }
 
-func main() {
+func logger(msg interface{}) {
+	log.Printf("%#v", msg)
+}
+
+func runner() {
 	defer func() {
 		if err := recover(); err != nil {
 			fmt.Println(err)
 			os.Exit(2)
 		}
 	}()
 
+	logger("Initiating IP update")
+
+	logger("Cloudflare DNS host found")
 	var cf = cloudflare.Cloudflare{}
 	cf.Proxied = true
 
 	if token, ok := os.LookupEnv("CF_token"); !ok {
 		panic(errors.New("cloudflare Token not set"))
 	} else {
+		logger("Cloudflare token found")
 		cf.Token = token
 	}
 
 	if domain, ok := os.LookupEnv("Domain"); !ok {
 		panic(errors.New("domain name not set"))
 	} else {
+		logger("Domain: " + domain)
 		cf.Domain = domain
 	}
 
 	if hostname, ok := os.LookupEnv("Subdomain"); !ok {
-		log.Print(hostname)
+		logger(hostname)
 		panic(errors.New("subdomain not set"))
 	} else {
 		cf.Hostname = hostname
 	}
 
 	if _, ok := os.LookupEnv("CF_proxy_disabled"); !ok {
-		log.Printf("CF_proxy_disabled not set")
+		logger("CF_proxy_disabled not set")
 	} else {
 		cf.Proxied = false
 	}
 
+	logger("Fetching new IP address")
 	ip := new(ipv4)
 
 	client := new(http.Client)
@@ -68,9 +82,32 @@ func main() {
 		}
 	}
 
+	logger(ip.IP)
+
 	cf.IpAddress = ip.IP
 
+	logger("Updating DNS record")
 	if err := cf.UpdateRecordSet(); err != nil {
 		panic(err)
 	}
+
+	logger("Update completed")
+}
+
+func main() {
+	interval := flag.Int64("freq", 2, "IP update frequency in hours. Default 2h")
+	flag.Parse()
+
+	sigs := make(chan os.Signal, 1)
+	signal.Notify(sigs, os.Interrupt, syscall.SIGINT, syscall.SIGTERM)
+	go func() {
+		s := <-sigs
+		log.Printf("RECEIVED SIGNAL: %s", s)
+		os.Exit(1)
+	}()
+
+	for {
+		runner()
+		time.Sleep(time.Hour * time.Duration(*interval))
+	}
 }