Add healthcheck endpoint

Author: limdingwen

src/healthcheck.go

@@ -0,0 +1,19 @@
+package main
+
+import (
+	"fmt"
+	"log"
+	"net/http"
+)
+
+func handler(w http.ResponseWriter, r *http.Request) {
+	fmt.Fprintf(w, "compose-updater online")
+}
+
+func Healthcheck() {
+	http.HandleFunc("/", handler)
+	log.Println("Starting healthcheck server at port 8080...")
+	if err := http.ListenAndServe(":8080", nil); err != nil {
+		log.Println(err)
+	}
+}

src/main.go

@@ -30,6 +30,7 @@ func printHeader() {
 
 func mainLoop() {
 	updater := &Updater{}
+	go Healthcheck();
 	for {
 		updater.PerformComposeUpdates()
 		if GlobalSettings.Once {