Merge pull request #373 from msekletar/freezer

dbus: implement support for cgroup freezer APIs

Author: Luca Bruno

dbus/methods.go

@@ -828,3 +828,14 @@ func (c *Conn) listJobsInternal(ctx context.Context) ([]JobStatus, error) {
 
 	return status, nil
 }
+
+// Freeze the cgroup associated with the unit.
+// Note that FreezeUnit and ThawUnit are only supported on systems running with cgroup v2.
+func (c *Conn) FreezeUnit(ctx context.Context, unit string) error {
+	return c.sysobj.CallWithContext(ctx, "org.freedesktop.systemd1.Manager.FreezeUnit", 0, unit).Store()
+}
+
+// Unfreeze the cgroup associated with the unit.
+func (c *Conn) ThawUnit(ctx context.Context, unit string) error {
+	return c.sysobj.CallWithContext(ctx, "org.freedesktop.systemd1.Manager.ThawUnit", 0, unit).Store()
+}

dbus/methods_test.go

@@ -15,6 +15,7 @@
 package dbus
 
 import (
+	"context"
 	"fmt"
 	"os"
 	"os/exec"
@@ -1600,3 +1601,59 @@ func TestUnitName(t *testing.T) {
 		}
 	}
 }
+
+func TestFreezer(t *testing.T) {
+	target := "freeze.service"
+	conn := setupConn(t)
+	defer conn.Close()
+
+	setupUnit(target, conn, t)
+	linkUnit(target, conn, t)
+
+	reschan := make(chan string)
+	_, err := conn.StartUnit(target, "replace", reschan)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	job := <-reschan
+	if job != "done" {
+		t.Fatal("Job is not done:", job)
+	}
+
+	if err := conn.FreezeUnit(context.Background(), target); err != nil {
+		// Don't fail the test if freezing units is not implemented at all (on older systemd versions) or
+		// not supported (on systems running with cgroup v1).
+		e, ok := err.(dbus.Error)
+		if ok && (e.Name == "org.freedesktop.DBus.Error.UnknownMethod" || e.Name == "org.freedesktop.DBus.Error.NotSupported") {
+			t.SkipNow()
+		}
+		t.Fatalf("failed to freeze unit %s: %s", target, err)
+	}
+
+	p, err := conn.GetUnitProperty(target, "FreezerState")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	v := p.Value.Value().(string)
+	if v != "frozen" {
+		t.Fatalf("unit is not frozen after calling FreezeUnit(), FreezerState=%s", v)
+	}
+
+	if err := conn.ThawUnit(context.Background(), target); err != nil {
+		t.Fatalf("failed to thaw unit %s: %s", target, err)
+	}
+
+	p, err = conn.GetUnitProperty(target, "FreezerState")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	v = p.Value.Value().(string)
+	if v != "running" {
+		t.Fatalf("unit is not frozen after calling ThawUnit(), FreezerState=%s", v)
+	}
+
+	runStopUnit(t, conn, TrUnitProp{target, nil})
+}

fixtures/freeze.service

@@ -0,0 +1,5 @@
+[Unit]
+Description=freeze unit test
+
+[Service]
+ExecStart=/bin/sleep 400