Add SetUnitProperties on a unit

Allows cgroup settings to be applied directly

Author: smarterclayton

dbus/methods.go

@@ -171,7 +171,18 @@ func (c *Conn) GetUnitProperties(unit string) (map[string]interface{}, error) {
 // Valid values for unitType: Service, Socket, Target, Device, Mount, Automount, Snapshot, Timer, Swap, Path, Slice, Scope
 // return "dbus.Error: Unknown interface" if the unitType is not the correct type of the unit
 func (c *Conn) GetUnitTypeProperties(unit string, unitType string) (map[string]interface{}, error) {
-	return c.getProperties(unit, "org.freedesktop.systemd1." + unitType)
+	return c.getProperties(unit, "org.freedesktop.systemd1."+unitType)
+}
+
+// SetUnitProperties() may be used to modify certain unit properties at runtime.
+// Not all properties may be changed at runtime, but many resource management
+// settings (primarily those in systemd.cgroup(5)) may. The changes are applied
+// instantly, and stored on disk for future boots, unless runtime is true, in which
+// case the settings only apply until the next reboot. name is the name of the unit
+// to modify. properties are the settings to set, encoded as an array of property
+// name and value pairs.
+func (c *Conn) SetUnitProperties(name string, runtime bool, properties ...Property) error {
+	return c.sysobj.Call("SetUnitProperties", 0, name, runtime, properties).Store()
 }
 
 // ListUnits returns an array with all currently loaded units. Note that

dbus/methods_test.go

@@ -18,6 +18,7 @@ package dbus
 
 import (
 	"fmt"
+	"github.com/guelfey/go.dbus"
 	"math/rand"
 	"os"
 	"path/filepath"
@@ -159,6 +160,29 @@ func TestGetUnitPropertiesRejectsInvalidName(t *testing.T) {
 	}
 }
 
+// TestSetUnitProperties changes a cgroup setting on the `tmp.mount`
+// which should exist on all systemd systems and ensures that the
+// property was set.
+func TestSetUnitProperties(t *testing.T) {
+	conn := setupConn(t)
+
+	unit := "tmp.mount"
+
+	if err := conn.SetUnitProperties(unit, true, Property{"CPUShares", dbus.MakeVariant(uint64(1023))}); err != nil {
+		t.Fatal(err)
+	}
+
+	info, err := conn.GetUnitTypeProperties(unit, "Mount")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	value := info["CPUShares"].(uint64)
+	if value != 1023 {
+		t.Fatal("CPUShares of unit is not 1023, %s", value)
+	}
+}
+
 // Ensure that basic transient unit starting and stopping works.
 func TestStartStopTransientUnit(t *testing.T) {
 	conn := setupConn(t)