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/*
Copyright The containerd Authors.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
package cgroups
import (
"path/filepath"
"strings"
"sync"
systemdDbus "github.com/coreos/go-systemd/v22/dbus"
"github.com/godbus/dbus/v5"
specs "github.com/opencontainers/runtime-spec/specs-go"
)
const (
SystemdDbus Name = "systemd"
defaultSlice = "system.slice"
)
var (
canDelegate bool
once sync.Once
)
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, name), nil
}
}
func NewSystemd(root string) (*SystemdController, error) {
return &SystemdController{
root: root,
}, nil
}
type SystemdController struct {
mu sync.Mutex
root string
}
func (s *SystemdController) Name() Name {
return SystemdDbus
}
func (s *SystemdController) Create(path string, _ *specs.LinuxResources) error {
conn, err := systemdDbus.New()
if err != nil {
return err
}
defer conn.Close()
slice, name := splitName(path)
// We need to see if systemd can handle the delegate property
// Systemd will return an error if it cannot handle delegate regardless
// of its bool setting.
checkDelegate := func() {
canDelegate = true
dlSlice := newProperty("Delegate", true)
if _, err := conn.StartTransientUnit(slice, "testdelegate", []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") {
canDelegate = false
}
}
}
conn.StopUnit(slice, "testDelegate", nil)
}
once.Do(checkDelegate)
properties := []systemdDbus.Property{
systemdDbus.PropDescription("cgroup " + name),
systemdDbus.PropWants(slice),
newProperty("DefaultDependencies", false),
newProperty("MemoryAccounting", true),
newProperty("CPUAccounting", true),
newProperty("BlockIOAccounting", true),
}
// If we can delegate, we add the property back in
if canDelegate {
properties = append(properties, newProperty("Delegate", true))
}
ch := make(chan string)
_, err = conn.StartTransientUnit(name, "replace", properties, ch)
if err != nil {
return err
}
<-ch
return nil
}
func (s *SystemdController) Delete(path string) error {
conn, err := systemdDbus.New()
if err != nil {
return err
}
defer conn.Close()
_, name := splitName(path)
ch := make(chan string)
_, err = conn.StopUnit(name, "replace", ch)
if err != nil {
return err
}
<-ch
return nil
}
func newProperty(name string, units interface{}) systemdDbus.Property {
return systemdDbus.Property{
Name: name,
Value: dbus.MakeVariant(units),
}
}
func splitName(path string) (slice string, unit string) {
slice, unit = filepath.Split(path)
return strings.TrimSuffix(slice, "/"), unit
}
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