feat: initialize a basic go daemon

cmd/ahenkd-go/ahenkd-go.go

@@ -0,0 +1,78 @@
+package main
+
+import (
+	"log"
+	"os"
+	"syscall"
+	"time"
+
+	"github.com/sevlyar/go-daemon"
+	"golang.org/x/exp/slices"
+)
+
+const PidFile = "/run/ahenkd-go.pid"
+const ExecutablePath = "/usr/bin/ahenkd-go"
+const ConfDir = "/etc/ahenk-go/"
+
+// FIXME there isn't any difference with Stop() function
+// TODO There can be a Start() function in it but start function doesnt work properly right now
+func Restart(pid, signal int) {
+	Stop(pid, signal)
+}
+
+// Stop Ahenkd Daemon with a specific PID (running from second copy)
+// do not forget to use also os.Exit() when using in ExecStop
+func Stop(pid, signal int) {
+	log.Println("Stop Signal Caught")
+
+	// FILLME what you want to do before stopping daemon?
+
+	if err := syscall.Kill(pid, syscall.Signal(signal)); err == nil {
+		log.Printf("Ahenk Daemon with pid number %v Successfully stopped", pid) // TODO Also log to /etc/ahenk-go/ahenkd.log
+	} else {
+		log.Fatal(err)
+	}
+}
+
+// Main Function that starts daemon and controls arguments
+func main() {
+	if len(os.Args) == 2 && slices.Contains([]string{"start", "stop", "restart"}, os.Args[1]) {
+		switch os.Args[1] {
+		case "start":
+			cntxt := &daemon.Context{
+				PidFileName: PidFile,
+				PidFilePerm: 0644,
+				LogFileName: ConfDir + "ahenkd.log",
+				LogFilePerm: 0640,
+				WorkDir:     ConfDir,
+				Umask:       027,
+				Args:        []string{ExecutablePath, "start"},
+			}
+			d, err := cntxt.Reborn()
+			if err != nil {
+				log.Fatal("Daemon Reborn ERROR:", err)
+			}
+			if d != nil {
+				return
+			}
+			defer cntxt.Release()
+			log.Println("- - - - - - - - - - - - - - - - - -")
+			log.Print("Daemon Succesfully Started")
+		case "stop":
+			i, _ := daemon.ReadPidFile(PidFile)
+			Stop(i, 15)
+			os.Exit(0)
+		case "restart":
+			i, _ := daemon.ReadPidFile(PidFile)
+			Restart(i, 15)
+			os.Exit(0)
+		}
+	}
+
+	for {
+		// NEXT Usage
+		log.Println("Working on it")
+		time.Sleep(2 * time.Second)
+	}
+
+}