make systemd and its dependencies optional via 'no_systemd' build tag (2nd take)

README.md

@@ -65,9 +65,10 @@ e.g. to disable seccomp:
 make BUILDTAGS=""
 ```
 
-| Build Tag | Feature                            | Enabled by default | Dependency |
-|-----------|------------------------------------|--------------------|------------|
-| seccomp   | Syscall filtering                  | yes                | libseccomp |
+| Build Tag  | Feature                            | Enabled by default | Dependency |
+|------------|------------------------------------|--------------------|------------|
+| seccomp    | Syscall filtering                  | yes                | libseccomp |
+| no_systemd | disable systemd dependencies       | no                 | systemd    |
 
 The following build tags were used earlier, but are now obsoleted:
  - **nokmem** (since runc v1.0.0-rc94 kernel memory settings are ignored)

libcontainer/cgroups/devices/devices.go

@@ -6,11 +6,10 @@ package devices
 
 import (
 	"github.com/opencontainers/runc/libcontainer/cgroups"
-	"github.com/opencontainers/runc/libcontainer/cgroups/systemd"
 )
 
 func init() {
 	cgroups.DevicesSetV1 = setV1
 	cgroups.DevicesSetV2 = setV2
-	systemd.GenerateDeviceProps = systemdProperties
+	initSystemd()
 }

libcontainer/cgroups/devices/no_systemd.go

@@ -0,0 +1,6 @@
+//go:build linux && no_systemd
+
+package devices
+
+func initSystemd() {
+}

libcontainer/cgroups/devices/systemd.go

@@ -1,3 +1,5 @@
+//go:build linux && !no_systemd
+
 package devices
 
 import (
@@ -7,22 +9,22 @@ import (
 	"strconv"
 	"strings"
 
-	systemdDbus "github.com/coreos/go-systemd/v22/dbus"
 	"github.com/godbus/dbus/v5"
 	"github.com/sirupsen/logrus"
 
+	"github.com/opencontainers/runc/libcontainer/cgroups/systemd"
 	"github.com/opencontainers/runc/libcontainer/configs"
 	"github.com/opencontainers/runc/libcontainer/devices"
 )
 
 // systemdProperties takes the configured device rules and generates a
 // corresponding set of systemd properties to configure the devices correctly.
-func systemdProperties(r *configs.Resources, sdVer int) ([]systemdDbus.Property, error) {
+func systemdProperties(r *configs.Resources, sdVer int) (configs.SdProperties, error) {
 	if r.SkipDevices {
 		return nil, nil
 	}
 
-	properties := []systemdDbus.Property{
+	properties := configs.SdProperties{
 		// Always run in the strictest white-list mode.
 		newProp("DevicePolicy", "strict"),
 		// Empty the DeviceAllow array before filling it.
@@ -158,8 +160,8 @@ func systemdProperties(r *configs.Resources, sdVer int) ([]systemdDbus.Property,
 	return properties, nil
 }
 
-func newProp(name string, units interface{}) systemdDbus.Property {
-	return systemdDbus.Property{
+func newProp(name string, units interface{}) configs.SdProperty {
+	return configs.SdProperty{
 		Name:  name,
 		Value: dbus.MakeVariant(units),
 	}
@@ -235,11 +237,15 @@ type deviceAllowEntry struct {
 	Perms string
 }
 
-func allowAllDevices() []systemdDbus.Property {
+func allowAllDevices() configs.SdProperties {
 	// Setting mode to auto and removing all DeviceAllow rules
 	// results in allowing access to all devices.
-	return []systemdDbus.Property{
+	return configs.SdProperties{
 		newProp("DevicePolicy", "auto"),
 		newProp("DeviceAllow", []deviceAllowEntry{}),
 	}
 }
+
+func initSystemd() {
+	systemd.GenerateDeviceProps = systemdProperties
+}

libcontainer/cgroups/systemd/common.go

@@ -1,3 +1,5 @@
+//go:build linux && !no_systemd
+
 package systemd
 
 import (
@@ -33,7 +35,7 @@ var (
 	isRunningSystemdOnce sync.Once
 	isRunningSystemd     bool
 
-	GenerateDeviceProps func(r *configs.Resources, sdVer int) ([]systemdDbus.Property, error)
+	GenerateDeviceProps func(r *configs.Resources, sdVer int) (configs.SdProperties, error)
 )
 
 // NOTE: This function comes from package github.com/coreos/go-systemd/util
@@ -85,8 +87,8 @@ func ExpandSlice(slice string) (string, error) {
 	return path, nil
 }
 
-func newProp(name string, units interface{}) systemdDbus.Property {
-	return systemdDbus.Property{
+func newProp(name string, units interface{}) configs.SdProperty {
+	return configs.SdProperty{
 		Name:  name,
 		Value: dbus.MakeVariant(units),
 	}
@@ -124,7 +126,7 @@ func isUnitExists(err error) bool {
 	return isDbusError(err, "org.freedesktop.systemd1.UnitExists")
 }
 
-func startUnit(cm *dbusConnManager, unitName string, properties []systemdDbus.Property, ignoreExist bool) error {
+func startUnit(cm *dbusConnManager, unitName string, properties configs.SdProperties, ignoreExist bool) error {
 	statusChan := make(chan string, 1)
 	retry := true
 
@@ -210,16 +212,16 @@ func resetFailedUnit(cm *dbusConnManager, name string) error {
 	})
 }
 
-func getUnitTypeProperty(cm *dbusConnManager, unitName string, unitType string, propertyName string) (*systemdDbus.Property, error) {
-	var prop *systemdDbus.Property
+func getUnitTypeProperty(cm *dbusConnManager, unitName string, unitType string, propertyName string) (*configs.SdProperty, error) {
+	var prop *configs.SdProperty
 	err := cm.retryOnDisconnect(func(c *systemdDbus.Conn) (Err error) {
 		prop, Err = c.GetUnitTypePropertyContext(context.TODO(), unitName, unitType, propertyName)
 		return Err
 	})
 	return prop, err
 }
 
-func setUnitProperties(cm *dbusConnManager, name string, properties ...systemdDbus.Property) error {
+func setUnitProperties(cm *dbusConnManager, name string, properties ...configs.SdProperty) error {
 	return cm.retryOnDisconnect(func(c *systemdDbus.Conn) error {
 		return c.SetUnitPropertiesContext(context.TODO(), name, true, properties...)
 	})
@@ -276,7 +278,7 @@ func systemdVersionAtoi(str string) (int, error) {
 	return ver, nil
 }
 
-func addCpuQuota(cm *dbusConnManager, properties *[]systemdDbus.Property, quota int64, period uint64) {
+func addCPUQuota(cm *dbusConnManager, properties *configs.SdProperties, quota int64, period uint64) {
 	if period != 0 {
 		// systemd only supports CPUQuotaPeriodUSec since v242
 		sdVer := systemdVersion(cm)
@@ -310,7 +312,7 @@ func addCpuQuota(cm *dbusConnManager, properties *[]systemdDbus.Property, quota
 	}
 }
 
-func addCpuset(cm *dbusConnManager, props *[]systemdDbus.Property, cpus, mems string) error {
+func addCpuset(cm *dbusConnManager, props *configs.SdProperties, cpus, mems string) error {
 	if cpus == "" && mems == "" {
 		return nil
 	}
@@ -346,7 +348,7 @@ func addCpuset(cm *dbusConnManager, props *[]systemdDbus.Property, cpus, mems st
 
 // generateDeviceProperties takes the configured device rules and generates a
 // corresponding set of systemd properties to configure the devices correctly.
-func generateDeviceProperties(r *configs.Resources, cm *dbusConnManager) ([]systemdDbus.Property, error) {
+func generateDeviceProperties(r *configs.Resources, cm *dbusConnManager) (configs.SdProperties, error) {
 	if GenerateDeviceProps == nil {
 		if len(r.Devices) > 0 {
 			return nil, cgroups.ErrDevicesUnsupported

libcontainer/cgroups/systemd/dbus.go

@@ -1,3 +1,5 @@
+//go:build linux && !no_systemd
+
 package systemd
 
 import (

libcontainer/cgroups/systemd/devices.go

@@ -1,3 +1,5 @@
+//go:build linux && !no_systemd
+
 package systemd
 
 import (

libcontainer/cgroups/systemd/no_systemd.go

@@ -0,0 +1,22 @@
+//go:build linux && no_systemd
+
+package systemd
+
+import (
+	"errors"
+
+	"github.com/opencontainers/runc/libcontainer/cgroups"
+	"github.com/opencontainers/runc/libcontainer/configs"
+)
+
+func IsRunningSystemd() bool {
+	return false
+}
+
+func NewUnifiedManager(config *configs.Cgroup, path string) (cgroups.Manager, error) {
+	return nil, errors.New("no systemd support")
+}
+
+func NewLegacyManager(cg *configs.Cgroup, paths map[string]string) (cgroups.Manager, error) {
+	return nil, errors.New("no systemd support")
+}

libcontainer/cgroups/systemd/systemd_test.go

@@ -1,11 +1,12 @@
+//go:build linux && !no_systemd
+
 package systemd
 
 import (
 	"os"
 	"reflect"
 	"testing"
 
-	systemdDbus "github.com/coreos/go-systemd/v22/dbus"
 	"github.com/opencontainers/runc/libcontainer/cgroups"
 	"github.com/opencontainers/runc/libcontainer/configs"
 )
@@ -113,7 +114,7 @@ func TestUnifiedResToSystemdProps(t *testing.T) {
 		minVer   int
 		res      map[string]string
 		expError bool
-		expProps []systemdDbus.Property
+		expProps configs.SdProperties
 	}{
 		{
 			name: "empty map",
@@ -125,7 +126,7 @@ func TestUnifiedResToSystemdProps(t *testing.T) {
 			res: map[string]string{
 				"cpu.idle": "1",
 			},
-			expProps: []systemdDbus.Property{
+			expProps: configs.SdProperties{
 				newProp("CPUWeight", uint64(0)),
 			},
 		},
@@ -143,7 +144,7 @@ func TestUnifiedResToSystemdProps(t *testing.T) {
 				"cpu.idle":   "1",
 				"cpu.weight": "1000",
 			},
-			expProps: []systemdDbus.Property{
+			expProps: configs.SdProperties{
 				newProp("CPUWeight", uint64(0)),
 			},
 		},
@@ -154,7 +155,7 @@ func TestUnifiedResToSystemdProps(t *testing.T) {
 				"cpu.idle":   "0",
 				"cpu.weight": "1000",
 			},
-			expProps: []systemdDbus.Property{
+			expProps: configs.SdProperties{
 				newProp("CPUWeight", uint64(1000)),
 			},
 		},

libcontainer/cgroups/systemd/user.go

@@ -1,3 +1,5 @@
+//go:build linux && !no_systemd
+
 package systemd
 
 import (

libcontainer/cgroups/systemd/v1.go

@@ -1,3 +1,5 @@
+//go:build linux && !no_systemd
+
 package systemd
 
 import (
@@ -72,8 +74,8 @@ var legacySubsystems = []subsystem{
 	&fs.NameGroup{GroupName: "misc"},
 }
 
-func genV1ResourcesProperties(r *configs.Resources, cm *dbusConnManager) ([]systemdDbus.Property, error) {
-	var properties []systemdDbus.Property
+func genV1ResourcesProperties(r *configs.Resources, cm *dbusConnManager) (configs.SdProperties, error) {
+	var properties configs.SdProperties
 
 	deviceProperties, err := generateDeviceProperties(r, cm)
 	if err != nil {
@@ -91,7 +93,7 @@ func genV1ResourcesProperties(r *configs.Resources, cm *dbusConnManager) ([]syst
 			newProp("CPUShares", r.CpuShares))
 	}
 
-	addCpuQuota(cm, &properties, r.CpuQuota, r.CpuPeriod)
+	addCPUQuota(cm, &properties, r.CpuQuota, r.CpuPeriod)
 
 	if r.BlkioWeight != 0 {
 		properties = append(properties,
@@ -163,7 +165,7 @@ func (m *LegacyManager) Apply(pid int) error {
 		c          = m.cgroups
 		unitName   = getUnitName(c)
 		slice      = "system.slice"
-		properties []systemdDbus.Property
+		properties configs.SdProperties
 	)
 
 	m.mu.Lock()

libcontainer/cgroups/systemd/v2.go

@@ -1,3 +1,5 @@
+//go:build linux && !no_systemd
+
 package systemd
 
 import (
@@ -69,7 +71,7 @@ func shouldSetCPUIdle(cm *dbusConnManager, v string) bool {
 // For the list of keys, see https://www.kernel.org/doc/Documentation/cgroup-v2.txt
 //
 // For the list of systemd unit properties, see systemd.resource-control(5).
-func unifiedResToSystemdProps(cm *dbusConnManager, res map[string]string) (props []systemdDbus.Property, _ error) {
+func unifiedResToSystemdProps(cm *dbusConnManager, res map[string]string) (props configs.SdProperties, _ error) {
 	var err error
 
 	for k, v := range res {
@@ -94,7 +96,7 @@ func unifiedResToSystemdProps(cm *dbusConnManager, res map[string]string) (props
 
 		case "cpu.max":
 			// value: quota [period]
-			quota := int64(0) // 0 means "unlimited" for addCpuQuota, if period is set
+			quota := int64(0) // 0 means "unlimited" for addCPUQuota, if period is set
 			period := defCPUQuotaPeriod
 			sv := strings.Fields(v)
 			if len(sv) < 1 || len(sv) > 2 {
@@ -114,7 +116,7 @@ func unifiedResToSystemdProps(cm *dbusConnManager, res map[string]string) (props
 					return nil, fmt.Errorf("unified resource %q quota value conversion error: %w", k, err)
 				}
 			}
-			addCpuQuota(cm, &props, quota, period)
+			addCPUQuota(cm, &props, quota, period)
 
 		case "cpu.weight":
 			if shouldSetCPUIdle(cm, strings.TrimSpace(res["cpu.idle"])) {
@@ -199,15 +201,15 @@ func unifiedResToSystemdProps(cm *dbusConnManager, res map[string]string) (props
 	return props, nil
 }
 
-func genV2ResourcesProperties(dirPath string, r *configs.Resources, cm *dbusConnManager) ([]systemdDbus.Property, error) {
+func genV2ResourcesProperties(dirPath string, r *configs.Resources, cm *dbusConnManager) (configs.SdProperties, error) {
 	// We need this check before setting systemd properties, otherwise
 	// the container is OOM-killed and the systemd unit is removed
 	// before we get to fsMgr.Set().
 	if err := fs2.CheckMemoryUsage(dirPath, r); err != nil {
 		return nil, err
 	}
 
-	var properties []systemdDbus.Property
+	var properties configs.SdProperties
 
 	// NOTE: This is of questionable correctness because we insert our own
 	//       devices eBPF program later. Two programs with identical rules
@@ -255,7 +257,7 @@ func genV2ResourcesProperties(dirPath string, r *configs.Resources, cm *dbusConn
 		}
 	}
 
-	addCpuQuota(cm, &properties, r.CpuQuota, r.CpuPeriod)
+	addCPUQuota(cm, &properties, r.CpuQuota, r.CpuPeriod)
 
 	if r.PidsLimit > 0 || r.PidsLimit == -1 {
 		properties = append(properties,
@@ -285,7 +287,7 @@ func (m *UnifiedManager) Apply(pid int) error {
 	var (
 		c          = m.cgroups
 		unitName   = getUnitName(c)
-		properties []systemdDbus.Property
+		properties configs.SdProperties
 	)
 
 	slice := "system.slice"

libcontainer/configs/cgroup_linux.go

@@ -1,7 +1,6 @@
 package configs
 
 import (
-	systemdDbus "github.com/coreos/go-systemd/v22/dbus"
 	"github.com/opencontainers/runc/libcontainer/devices"
 )
 
@@ -37,7 +36,7 @@ type Cgroup struct {
 	// SystemdProps are any additional properties for systemd,
 	// derived from org.systemd.property.xxx annotations.
 	// Ignored unless systemd is used for managing cgroups.
-	SystemdProps []systemdDbus.Property `json:"-"`
+	SystemdProps SdProperties `json:"-"`
 
 	// Rootless tells if rootless cgroups should be used.
 	Rootless bool

libcontainer/configs/no_systemd.go

@@ -0,0 +1,8 @@
+//go:build linux && no_systemd
+
+package configs
+
+type (
+	SdProperty   = int
+	SdProperties = int
+)