Merge pull request #1776 from filbranden/systemd2

Detect whether Delegate is available on both slices and scopes

Author: crosbymichael

libcontainer/cgroups/systemd/apply_systemd.go

@@ -75,7 +75,8 @@ var (
 	hasStartTransientUnit           bool
 	hasStartTransientSliceUnit      bool
 	hasTransientDefaultDependencies bool
-	hasDelegate                     bool
+	hasDelegateScope                bool
+	hasDelegateSlice                bool
 )
 
 func newProp(name string, units interface{}) systemdDbus.Property {
@@ -150,12 +151,12 @@ func UseSystemd() bool {
 		theConn.StopUnit(scope, "replace", nil)
 
 		// Assume StartTransientUnit on a scope allows Delegate
-		hasDelegate = true
-		dl := newProp("Delegate", true)
-		if _, err := theConn.StartTransientUnit(scope, "replace", []systemdDbus.Property{dl}, nil); err != nil {
+		hasDelegateScope = true
+		dlScope := newProp("Delegate", true)
+		if _, err := theConn.StartTransientUnit(scope, "replace", []systemdDbus.Property{dlScope}, nil); err != nil {
 			if dbusError, ok := err.(dbus.Error); ok {
 				if strings.Contains(dbusError.Name, "org.freedesktop.DBus.Error.PropertyReadOnly") {
-					hasDelegate = false
+					hasDelegateScope = false
 				}
 			}
 		}
@@ -187,6 +188,22 @@ func UseSystemd() bool {
 			time.Sleep(time.Millisecond)
 		}
 
+		// Not critical because of the stop unit logic above.
+		theConn.StopUnit(slice, "replace", nil)
+
+		// Assume StartTransientUnit on a slice allows Delegate
+		hasDelegateSlice = true
+		dlSlice := newProp("Delegate", true)
+		if _, err := theConn.StartTransientUnit(slice, "replace", []systemdDbus.Property{dlSlice}, nil); err != nil {
+			if dbusError, ok := err.(dbus.Error); ok {
+				// Starting with systemd v237, Delegate is not even a property of slices anymore,
+				// so the D-Bus call fails with "InvalidArgs" error.
+				if strings.Contains(dbusError.Name, "org.freedesktop.DBus.Error.PropertyReadOnly") || strings.Contains(dbusError.Name, "org.freedesktop.DBus.Error.InvalidArgs") {
+					hasDelegateSlice = false
+				}
+			}
+		}
+
 		// Not critical because of the stop unit logic above.
 		theConn.StopUnit(scope, "replace", nil)
 		theConn.StopUnit(slice, "replace", nil)
@@ -242,9 +259,16 @@ func (m *Manager) Apply(pid int) error {
 		properties = append(properties, newProp("PIDs", []uint32{uint32(pid)}))
 	}
 
-	if hasDelegate {
-		// This is only supported on systemd versions 218 and above.
-		properties = append(properties, newProp("Delegate", true))
+	// Check if we can delegate. This is only supported on systemd versions 218 and above.
+	if strings.HasSuffix(unitName, ".slice") {
+		if hasDelegateSlice {
+			// systemd 237 and above no longer allows delegation on a slice
+			properties = append(properties, newProp("Delegate", true))
+		}
+	} else {
+		if hasDelegateScope {
+			properties = append(properties, newProp("Delegate", true))
+		}
 	}
 
 	// Always enable accounting, this gets us the same behaviour as the fs implementation,