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Remove libcontainer detection for systemd features #2117

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Merged
mrunalp merged 1 commit into from
Aug 25, 2019
Merged

Remove libcontainer detection for systemd features #2117

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79 changes: 4 additions & 75 deletions libcontainer/cgroups/systemd/apply_systemd.go
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Original file line number Diff line number Diff line change
Expand Up @@ -72,11 +72,8 @@ const (
)

var (
connLock sync.Mutex
theConn *systemdDbus.Conn
hasStartTransientUnit bool
hasStartTransientSliceUnit bool
hasDelegateSlice bool
connLock sync.Mutex
theConn *systemdDbus.Conn
)

func newProp(name string, units interface{}) systemdDbus.Property {
Expand All @@ -100,67 +97,8 @@ func UseSystemd() bool {
if err != nil {
return false
}

// Assume we have StartTransientUnit
hasStartTransientUnit = true

// But if we get UnknownMethod error we don't
if _, err := theConn.StartTransientUnit("test.scope", "invalid", nil, nil); err != nil {
if dbusError, ok := err.(dbus.Error); ok {
if dbusError.Name == "org.freedesktop.DBus.Error.UnknownMethod" {
hasStartTransientUnit = false
return hasStartTransientUnit
}
}
}

// Assume we have the ability to start a transient unit as a slice
// This was broken until systemd v229, but has been back-ported on RHEL environments >= 219
// For details, see: https://bugzilla.redhat.com/show_bug.cgi?id=1370299
hasStartTransientSliceUnit = true

// To ensure simple clean-up, we create a slice off the root with no hierarchy
slice := fmt.Sprintf("libcontainer_%d_systemd_test_default.slice", os.Getpid())
if _, err := theConn.StartTransientUnit(slice, "replace", nil, nil); err != nil {
if _, ok := err.(dbus.Error); ok {
hasStartTransientSliceUnit = false
}
}

for i := 0; i <= testSliceWait; i++ {
if _, err := theConn.StopUnit(slice, "replace", nil); err != nil {
if dbusError, ok := err.(dbus.Error); ok {
if strings.Contains(dbusError.Name, "org.freedesktop.systemd1.NoSuchUnit") {
hasStartTransientSliceUnit = false
break
}
}
} else {
break
}
time.Sleep(time.Millisecond)
}

// Not critical because of the stop unit logic above.
theConn.StopUnit(slice, "replace", nil)

// Assume StartTransientUnit on a slice allows Delegate
hasDelegateSlice = true
dlSlice := newProp("Delegate", true)
if _, err := theConn.StartTransientUnit(slice, "replace", []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") {
hasDelegateSlice = false
}
}
}

// Not critical because of the stop unit logic above.
theConn.StopUnit(slice, "replace", nil)
}
return hasStartTransientUnit
return true
}

func NewSystemdCgroupsManager() (func(config *configs.Cgroup, paths map[string]string) cgroups.Manager, error) {
Expand Down Expand Up @@ -208,10 +146,6 @@ func (m *Manager) Apply(pid int) error {

// if we create a slice, the parent is defined via a Wants=
if strings.HasSuffix(unitName, ".slice") {
// This was broken until systemd v229, but has been back-ported on RHEL environments >= 219
if !hasStartTransientSliceUnit {
return fmt.Errorf("systemd version does not support ability to start a slice as transient unit")
}
properties = append(properties, systemdDbus.PropWants(slice))
} else {
// otherwise, we use Slice=
Expand All @@ -224,12 +158,7 @@ func (m *Manager) Apply(pid int) error {
}

// Check if we can delegate. This is only supported on systemd versions 218 and above.
if strings.HasSuffix(unitName, ".slice") {
if hasDelegateSlice {
// systemd 237 and above no longer allows delegation on a slice
properties = append(properties, newProp("Delegate", true))
}
} else {
if !strings.HasSuffix(unitName, ".slice") {
// Assume scopes always support delegation.
properties = append(properties, newProp("Delegate", true))
}
Expand Down