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Remove libcontainer detection for systemd features 

Transient units (and transient slice units) have been available for quite a
long time and RHEL 7 with systemd v219 (likely the oldest OS we care about at
this point) supports that. A system running a systemd without these features is
likely to break a lot of other stuff that runc/libcontainer care about.

Regarding delegated slices, modern systemd doesn't allow it and
runc/libcontainer run fine on it, so we might as well just stop requesting it
on older versions of systemd which allowed it. (Those versions never really
changed behavior significantly when that option was passed anyways.)

Signed-off-by: Filipe Brandenburger <filbranden@gmail.com>
This commit is contained in:
Filipe Brandenburger 2019-08-22 21:53:24 -07:00
parent 2e94378464
commit 518c855833
1 changed files with 4 additions and 75 deletions
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75
libcontainer/cgroups/systemd/apply_systemd.go
View File

@ -74,9 +74,6 @@ const (
var (
connLock sync.Mutex
theConn *systemdDbus.Conn
hasStartTransientUnit bool
hasStartTransientSliceUnit bool
hasDelegateSlice bool
)
func newProp(name string, units interface{}) systemdDbus.Property {
@ -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) {
@ -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=
@ -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))
}