Add command line flags, and improve updater package

main.go

@@ -1,21 +1,46 @@
 package main
 
 import (
-	"log"
+	"flag"
+	"fmt"
 	"os"
 
 	"github.com/jimeh/cloudflare-dyndns/updater"
 )
 
 func main() {
-	var email = os.Getenv("CF_EMAIL")
-	var apiKey = os.Getenv("CF_API")
-	var host = os.Getenv("CF_HOST")
+	var email string
+	var apiKey string
+	var host string
+
+	flag.StringVar(
+		&email, "email", os.Getenv("CF_EMAIL"),
+		"Cloudflare email account. Can be specified via CF_EMAIL env var.",
+	)
+	flag.StringVar(
+		&apiKey, "apikey", os.Getenv("CF_APIKEY"),
+		"Cloudflare API key. Can be specified via CF_APIKEY env var.",
+	)
+	flag.StringVar(
+		&host, "host", os.Getenv("CF_HOST"),
+		"DNS entry to update. Can be specified via CF_HOST env var.",
+	)
+
+	flag.Parse()
+
+	if email == "" || apiKey == "" || host == "" {
+		fmt.Println("usage: cloudflare-dyndns <options>\n\noptions:")
+		flag.PrintDefaults()
+		os.Exit(1)
+	}
 
 	updater := updater.New(email, apiKey)
 
-	err := updater.Update(host)
+	stop, err := updater.UpdateLoop(host)
 	if err != nil {
-		log.Fatal(err)
+		fmt.Printf("ERROR: %s\n", err.Error())
+		os.Exit(1)
 	}
+
+	<-stop // wait forever
 }

updater/updater.go

@@ -38,25 +38,51 @@ type Updater struct {
 	Interval   int
 }
 
-// Update performs a the full update sequence.
-func (u *Updater) Update(host string) error {
+// UpdateLoop performs a the full update sequence.
+func (u *Updater) UpdateLoop(host string) (<-chan bool, error) {
+	stop := make(chan bool, 1)
+
 	fmt.Printf("Looking up record for %s...\n", host)
+	record, err := u.RecordByHost(host)
+	if err != nil {
+		return stop, err
+	}
+
+	fmt.Printf("Found %s (Zone: %s)\n", record.Name, record.ZoneName)
+	go func() {
+		fmt.Printf("Starting IP check (repeats every %d seconds)\n", u.Interval)
+
+		_, err = u.UpdateRecord(record)
+		if err != nil {
+			fmt.Printf("ERROR: %s\n", err.Error())
+		}
+
+		for {
+			select {
+			case <-stop:
+				close(stop)
+				return
+			case <-time.After(time.Second * time.Duration(u.Interval)):
+				_, err = u.UpdateRecord(record)
+				if err != nil {
+					fmt.Printf("ERROR: %s\n", err.Error())
+				}
+			}
+		}
+	}()
+
+	return stop, nil
+}
+
+// Update performs a single update
+func (u *Updater) Update(host string) error {
 	record, err := u.RecordByHost(host)
 	if err != nil {
 		return err
 	}
-	fmt.Printf("Found %s (%s)\n", record.Name, record.ID)
 
-	fmt.Printf("Starting IP check (repeats every %d seconds)\n", u.Interval)
-	for {
-		record, err = u.UpdateRecord(record)
-		if err != nil {
-			fmt.Printf("ERROR: %s\n", err.Error())
-			fmt.Printf("Retrying in %d seconds...", u.Interval)
-		}
-
-		time.Sleep(time.Duration(u.Interval) * time.Second)
-	}
+	_, err = u.UpdateRecord(record)
+	return err
 }
 
 // UpdateRecord updates a cloudflare.DNSRecord.