systemd notify and watchdog (closes #12)

cmd/circologd/main.go

@@ -9,8 +9,10 @@ import (
 	"os"
 	"os/signal"
 	"syscall"
+	"time"
 
 	"git.lattuga.net/boyska/circolog"
+	"github.com/coreos/go-systemd/daemon"
 	syslog "gopkg.in/mcuadros/go-syslog.v2"
 )
 
@@ -103,10 +105,17 @@ func main() {
 		}()
 	}
 
-	// TODO: now we are ready
+	daemon.SdNotify(false, daemon.SdNotifyReady)
 
+	var wdTick <-chan time.Time
+	if watchdogTime, err := daemon.SdWatchdogEnabled(false); err == nil && watchdogTime != 0 {
+		fmt.Println("systemd watchdog enabled")
+		wdTick = time.Tick(watchdogTime / 2) // much less than systemd default of 30s; TODO: make it configurable
+	}
 	for {
 		select {
+		case <-wdTick:
+			daemon.SdNotify(false, daemon.SdNotifyWatchdog)
 		case sig := <-interrupt:
 			if sig == syscall.SIGUSR1 {
 				response := make(chan circolog.CommandResponse)
@@ -130,6 +139,7 @@ func main() {
 			}
 			if sig == syscall.SIGTERM || sig == syscall.SIGINT {
 				log.Println("Quitting because of signal", sig)
+				daemon.SdNotify(false, daemon.SdNotifyStopping)
 				server.Kill()
 				if err := httpQueryServer.Shutdown(nil); err != nil {
 					fmt.Fprintln(os.Stderr, "Error closing http server:", err)