libcontainer: add systemd.UnifiedManager

Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com>

libcontainer/cgroups/systemd/apply_systemd.go

@@ -119,6 +119,14 @@ func NewSystemdCgroupsManager() (func(config *configs.Cgroup, paths map[string]s
 	if !isRunningSystemd() {
 		return nil, fmt.Errorf("systemd not running on this host, can't use systemd as a cgroups.Manager")
 	}
+	if cgroups.IsCgroup2UnifiedMode() {
+		return func(config *configs.Cgroup, paths map[string]string) cgroups.Manager {
+			return &UnifiedManager{
+				Cgroups: config,
+				Paths:   paths,
+			}
+		}, nil
+	}
 	return func(config *configs.Cgroup, paths map[string]string) cgroups.Manager {
 		return &LegacyManager{
 			Cgroups: config,
@@ -407,7 +415,7 @@ func (m *LegacyManager) Freeze(state configs.FreezerState) error {
 	}
 	prevState := m.Cgroups.Resources.Freezer
 	m.Cgroups.Resources.Freezer = state
-	freezer, err := subsystems.Get("freezer")
+	freezer, err := legacySubsystems.Get("freezer")
 	if err != nil {
 		return err
 	}
@@ -440,7 +448,7 @@ func (m *LegacyManager) GetStats() (*cgroups.Stats, error) {
 	defer m.mu.Unlock()
 	stats := cgroups.NewStats()
 	for name, path := range m.Paths {
-		sys, err := subsystems.Get(name)
+		sys, err := legacySubsystems.Get(name)
 		if err == errSubsystemDoesNotExist || !cgroups.PathExists(path) {
 			continue
 		}

libcontainer/cgroups/systemd/unified_hierarchy.go

@@ -0,0 +1,329 @@
+// +build linux,!static_build
+
+package systemd
+
+import (
+	"fmt"
+	"io/ioutil"
+	"math"
+	"os"
+	"path/filepath"
+	"strings"
+	"sync"
+	"time"
+
+	systemdDbus "github.com/coreos/go-systemd/dbus"
+	"github.com/opencontainers/runc/libcontainer/cgroups"
+	"github.com/opencontainers/runc/libcontainer/cgroups/fs"
+	"github.com/opencontainers/runc/libcontainer/configs"
+	"github.com/sirupsen/logrus"
+)
+
+type UnifiedManager struct {
+	mu      sync.Mutex
+	Cgroups *configs.Cgroup
+	Paths   map[string]string
+}
+
+var unifiedSubsystems = subsystemSet{
+	&fs.CpusetGroupV2{},
+	&fs.FreezerGroupV2{},
+	&fs.CpuGroupV2{},
+	&fs.MemoryGroupV2{},
+	&fs.IOGroupV2{},
+	&fs.PidsGroupV2{},
+}
+
+func (m *UnifiedManager) Apply(pid int) error {
+	var (
+		c          = m.Cgroups
+		unitName   = getUnitName(c)
+		slice      = "system.slice"
+		properties []systemdDbus.Property
+	)
+
+	if c.Paths != nil {
+		paths := make(map[string]string)
+		for name, path := range c.Paths {
+			_, err := getSubsystemPath(m.Cgroups, name)
+			if err != nil {
+				// Don't fail if a cgroup hierarchy was not found, just skip this subsystem
+				if cgroups.IsNotFound(err) {
+					continue
+				}
+				return err
+			}
+			paths[name] = path
+		}
+		m.Paths = paths
+		return cgroups.EnterPid(m.Paths, pid)
+	}
+
+	if c.Parent != "" {
+		slice = c.Parent
+	}
+
+	properties = append(properties, systemdDbus.PropDescription("libcontainer container "+c.Name))
+
+	// if we create a slice, the parent is defined via a Wants=
+	if strings.HasSuffix(unitName, ".slice") {
+		properties = append(properties, systemdDbus.PropWants(slice))
+	} else {
+		// otherwise, we use Slice=
+		properties = append(properties, systemdDbus.PropSlice(slice))
+	}
+
+	// only add pid if its valid, -1 is used w/ general slice creation.
+	if pid != -1 {
+		properties = append(properties, newProp("PIDs", []uint32{uint32(pid)}))
+	}
+
+	// Check if we can delegate. This is only supported on systemd versions 218 and above.
+	if !strings.HasSuffix(unitName, ".slice") {
+		// Assume scopes always support delegation.
+		properties = append(properties, newProp("Delegate", true))
+	}
+
+	// Always enable accounting, this gets us the same behaviour as the fs implementation,
+	// plus the kernel has some problems with joining the memory cgroup at a later time.
+	properties = append(properties,
+		newProp("MemoryAccounting", true),
+		newProp("CPUAccounting", true),
+		newProp("BlockIOAccounting", true))
+
+	// Assume DefaultDependencies= will always work (the check for it was previously broken.)
+	properties = append(properties,
+		newProp("DefaultDependencies", false))
+
+	if c.Resources.Memory != 0 {
+		properties = append(properties,
+			newProp("MemoryLimit", uint64(c.Resources.Memory)))
+	}
+
+	if c.Resources.CpuShares != 0 {
+		properties = append(properties,
+			newProp("CPUShares", c.Resources.CpuShares))
+	}
+
+	// cpu.cfs_quota_us and cpu.cfs_period_us are controlled by systemd.
+	if c.Resources.CpuQuota != 0 && c.Resources.CpuPeriod != 0 {
+		// corresponds to USEC_INFINITY in systemd
+		// if USEC_INFINITY is provided, CPUQuota is left unbound by systemd
+		// always setting a property value ensures we can apply a quota and remove it later
+		cpuQuotaPerSecUSec := uint64(math.MaxUint64)
+		if c.Resources.CpuQuota > 0 {
+			// systemd converts CPUQuotaPerSecUSec (microseconds per CPU second) to CPUQuota
+			// (integer percentage of CPU) internally.  This means that if a fractional percent of
+			// CPU is indicated by Resources.CpuQuota, we need to round up to the nearest
+			// 10ms (1% of a second) such that child cgroups can set the cpu.cfs_quota_us they expect.
+			cpuQuotaPerSecUSec = uint64(c.Resources.CpuQuota*1000000) / c.Resources.CpuPeriod
+			if cpuQuotaPerSecUSec%10000 != 0 {
+				cpuQuotaPerSecUSec = ((cpuQuotaPerSecUSec / 10000) + 1) * 10000
+			}
+		}
+		properties = append(properties,
+			newProp("CPUQuotaPerSecUSec", cpuQuotaPerSecUSec))
+	}
+
+	if c.Resources.BlkioWeight != 0 {
+		properties = append(properties,
+			newProp("BlockIOWeight", uint64(c.Resources.BlkioWeight)))
+	}
+
+	if c.Resources.PidsLimit > 0 {
+		properties = append(properties,
+			newProp("TasksAccounting", true),
+			newProp("TasksMax", uint64(c.Resources.PidsLimit)))
+	}
+
+	// We have to set kernel memory here, as we can't change it once
+	// processes have been attached to the cgroup.
+	if c.Resources.KernelMemory != 0 {
+		if err := setKernelMemory(c); err != nil {
+			return err
+		}
+	}
+
+	statusChan := make(chan string, 1)
+	if _, err := theConn.StartTransientUnit(unitName, "replace", properties, statusChan); err == nil {
+		select {
+		case <-statusChan:
+		case <-time.After(time.Second):
+			logrus.Warnf("Timed out while waiting for StartTransientUnit(%s) completion signal from dbus. Continuing...", unitName)
+		}
+	} else if !isUnitExists(err) {
+		return err
+	}
+
+	if err := joinCgroupsV2(c, pid); err != nil {
+		return err
+	}
+
+	paths := make(map[string]string)
+	for _, s := range unifiedSubsystems {
+		subsystemPath, err := getSubsystemPath(m.Cgroups, s.Name())
+		if err != nil {
+			// Don't fail if a cgroup hierarchy was not found, just skip this subsystem
+			if cgroups.IsNotFound(err) {
+				continue
+			}
+			return err
+		}
+		paths[s.Name()] = subsystemPath
+	}
+	m.Paths = paths
+	return nil
+}
+
+func (m *UnifiedManager) Destroy() error {
+	if m.Cgroups.Paths != nil {
+		return nil
+	}
+	m.mu.Lock()
+	defer m.mu.Unlock()
+	theConn.StopUnit(getUnitName(m.Cgroups), "replace", nil)
+	if err := cgroups.RemovePaths(m.Paths); err != nil {
+		return err
+	}
+	m.Paths = make(map[string]string)
+	return nil
+}
+
+func (m *UnifiedManager) GetPaths() map[string]string {
+	m.mu.Lock()
+	paths := m.Paths
+	m.mu.Unlock()
+	return paths
+}
+
+func createCgroupsv2Path(path string) (Err error) {
+	content, err := ioutil.ReadFile("/sys/fs/cgroup/cgroup.controllers")
+	if err != nil {
+		return err
+	}
+	if !filepath.HasPrefix(path, "/sys/fs/cgroup") {
+		return fmt.Errorf("invalid cgroup path %s", path)
+	}
+
+	res := ""
+	for i, c := range strings.Split(strings.TrimSpace(string(content)), " ") {
+		if i == 0 {
+			res = fmt.Sprintf("+%s", c)
+		} else {
+			res = res + fmt.Sprintf(" +%s", c)
+		}
+	}
+	resByte := []byte(res)
+
+	current := "/sys/fs"
+	elements := strings.Split(path, "/")
+	for i, e := range elements[3:] {
+		current = filepath.Join(current, e)
+		if i > 0 {
+			if err := os.Mkdir(current, 0755); err != nil {
+				if !os.IsExist(err) {
+					return err
+				}
+			} else {
+				// If the directory was created, be sure it is not left around on errors.
+				defer func() {
+					if Err != nil {
+						os.Remove(current)
+					}
+				}()
+			}
+		}
+		if i < len(elements[3:])-1 {
+			if err := ioutil.WriteFile(filepath.Join(current, "cgroup.subtree_control"), resByte, 0755); err != nil {
+				return err
+			}
+		}
+	}
+	return nil
+}
+
+func joinCgroupsV2(c *configs.Cgroup, pid int) error {
+	path, err := getSubsystemPath(c, "memory")
+	if err != nil {
+		return err
+	}
+	return createCgroupsv2Path(path)
+}
+
+func (m *UnifiedManager) Freeze(state configs.FreezerState) error {
+	path, err := getSubsystemPath(m.Cgroups, "freezer")
+	if err != nil {
+		return err
+	}
+	prevState := m.Cgroups.Resources.Freezer
+	m.Cgroups.Resources.Freezer = state
+	freezer, err := unifiedSubsystems.Get("freezer")
+	if err != nil {
+		return err
+	}
+	err = freezer.Set(path, m.Cgroups)
+	if err != nil {
+		m.Cgroups.Resources.Freezer = prevState
+		return err
+	}
+	return nil
+}
+
+func (m *UnifiedManager) GetPids() ([]int, error) {
+	path, err := getSubsystemPath(m.Cgroups, "devices")
+	if err != nil {
+		return nil, err
+	}
+	return cgroups.GetPids(path)
+}
+
+func (m *UnifiedManager) GetAllPids() ([]int, error) {
+	path, err := getSubsystemPath(m.Cgroups, "devices")
+	if err != nil {
+		return nil, err
+	}
+	return cgroups.GetAllPids(path)
+}
+
+func (m *UnifiedManager) GetStats() (*cgroups.Stats, error) {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+	stats := cgroups.NewStats()
+	for name, path := range m.Paths {
+		sys, err := unifiedSubsystems.Get(name)
+		if err == errSubsystemDoesNotExist || !cgroups.PathExists(path) {
+			continue
+		}
+		if err := sys.GetStats(path, stats); err != nil {
+			return nil, err
+		}
+	}
+
+	return stats, nil
+}
+
+func (m *UnifiedManager) Set(container *configs.Config) error {
+	// If Paths are set, then we are just joining cgroups paths
+	// and there is no need to set any values.
+	if m.Cgroups.Paths != nil {
+		return nil
+	}
+	for _, sys := range unifiedSubsystems {
+		// Get the subsystem path, but don't error out for not found cgroups.
+		path, err := getSubsystemPath(container.Cgroups, sys.Name())
+		if err != nil && !cgroups.IsNotFound(err) {
+			return err
+		}
+
+		if err := sys.Set(path, container.Cgroups); err != nil {
+			return err
+		}
+	}
+
+	if m.Paths["cpu"] != "" {
+		if err := fs.CheckCpushares(m.Paths["cpu"], container.Cgroups.Resources.CpuShares); err != nil {
+			return err
+		}
+	}
+	return nil
+}