oci: join crio-conmon for cgroupfs

Signed-off-by: Antonio Murdaca <runcom@redhat.com>

vendor/github.com/containerd/cgroups/systemd.go

@@ -0,0 +1,101 @@
+package cgroups
+
+import (
+	"fmt"
+	"path/filepath"
+	"strings"
+	"sync"
+
+	systemdDbus "github.com/coreos/go-systemd/dbus"
+	"github.com/godbus/dbus"
+	specs "github.com/opencontainers/runtime-spec/specs-go"
+)
+
+const (
+	SystemdDbus  Name = "systemd"
+	defaultSlice      = "system.slice"
+)
+
+func Systemd() ([]Subsystem, error) {
+	root, err := v1MountPoint()
+	if err != nil {
+		return nil, err
+	}
+	defaultSubsystems, err := defaults(root)
+	if err != nil {
+		return nil, err
+	}
+	s, err := NewSystemd(root)
+	if err != nil {
+		return nil, err
+	}
+	// make sure the systemd controller is added first
+	return append([]Subsystem{s}, defaultSubsystems...), nil
+}
+
+func Slice(slice, name string) Path {
+	if slice == "" {
+		slice = defaultSlice
+	}
+	return func(subsystem Name) (string, error) {
+		return filepath.Join(slice, unitName(name)), nil
+	}
+}
+
+func NewSystemd(root string) (*SystemdController, error) {
+	conn, err := systemdDbus.New()
+	if err != nil {
+		return nil, err
+	}
+	return &SystemdController{
+		root: root,
+		conn: conn,
+	}, nil
+}
+
+type SystemdController struct {
+	mu   sync.Mutex
+	conn *systemdDbus.Conn
+	root string
+}
+
+func (s *SystemdController) Name() Name {
+	return SystemdDbus
+}
+
+func (s *SystemdController) Create(path string, resources *specs.LinuxResources) error {
+	slice, name := splitName(path)
+	properties := []systemdDbus.Property{
+		systemdDbus.PropDescription(fmt.Sprintf("cgroup %s", name)),
+		systemdDbus.PropWants(slice),
+		newProperty("DefaultDependencies", false),
+		newProperty("Delegate", true),
+		newProperty("MemoryAccounting", true),
+		newProperty("CPUAccounting", true),
+		newProperty("BlockIOAccounting", true),
+	}
+	_, err := s.conn.StartTransientUnit(name, "replace", properties, nil)
+	return err
+}
+
+func (s *SystemdController) Delete(path string) error {
+	_, name := splitName(path)
+	_, err := s.conn.StopUnit(name, "replace", nil)
+	return err
+}
+
+func newProperty(name string, units interface{}) systemdDbus.Property {
+	return systemdDbus.Property{
+		Name:  name,
+		Value: dbus.MakeVariant(units),
+	}
+}
+
+func unitName(name string) string {
+	return fmt.Sprintf("%s.slice", name)
+}
+
+func splitName(path string) (slice string, unit string) {
+	slice, unit = filepath.Split(path)
+	return strings.TrimSuffix(slice, "/"), unit
+}