From 16c07fde4b42101f016661d2406186b7d3394d17 Mon Sep 17 00:00:00 2001
From: Tim Serong <tserong@suse.com>
Date: Wed, 21 Aug 2024 16:23:06 +1000
Subject: [PATCH] feat: Add TryRestartService()

This is just like the existing RestartService() function, except
it only applies to services that are already running.

Related issue: https://github.com/harvester/harvester/issues/5274

Signed-off-by: Tim Serong <tserong@suse.com>
---
 sys/systemd-dbus.go | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/sys/systemd-dbus.go b/sys/systemd-dbus.go
index 0e00c68..b5e580f 100644
--- a/sys/systemd-dbus.go
+++ b/sys/systemd-dbus.go
@@ -7,6 +7,7 @@ import (
 	"github.com/sirupsen/logrus"
 )
 
+// RestartService restarts a service.  If the service isn't already running it will be started.
 func RestartService(unit string) error {
 	ctx := context.Background()
 	conn, err := dbus.NewWithContext(ctx)
@@ -21,3 +22,20 @@ func RestartService(unit string) error {
 	}
 	return nil
 }
+
+// TryRestartService will restart a service, but only if it's currently running.
+// A service that isn't running won't be affected.
+func TryRestartService(unit string) error {
+	ctx := context.Background()
+	conn, err := dbus.NewWithContext(ctx)
+	if err != nil {
+		logrus.Errorf("Failed to create new connection for systemd. err: %v", err)
+		return err
+	}
+	responseChan := make(chan string, 1)
+	if _, err := conn.TryRestartUnitContext(ctx, unit, "fail", responseChan); err != nil {
+		logrus.Errorf("Failed to restart service %s. err: %v", unit, err)
+		return err
+	}
+	return nil
+}