Merge pull request #61926 from filbranden/cgroupdriver10

Automatic merge from submit-queue. If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

Update libcontainer to include PRs with fixes to systemd cgroup driver

**What this PR does / why we need it**:

PR opencontainers/runc#1754 works around an issue in manager.Apply(-1) that makes Kubelet startup hang when using systemd cgroup driver (by adding a timeout) and further PR opencontainers/runc#1772 fixes that bug by checking the proper error status before waiting on the channel.
    
PR opencontainers/runc#1776 checks whether Delegate works in slices, which keeps libcontainer systemd cgroup driver working on systemd v237+.

**Which issue(s) this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close the issue(s) when PR gets merged)*:
Fixes #61474

**Special notes for your reviewer**:
/assign @derekwaynecarr
cc @vikaschoudhary16 @sjenning @adelton @mrunalp 

**Release note**:

```release-note
NONE
```

Godeps/Godeps.json

@@ -2358,83 +2358,83 @@
 		},
 		{
 			"ImportPath": "github.com/opencontainers/runc/libcontainer",
-			"Comment": "v1.0.0-rc4-221-g595bea02",
+			"Comment": "v1.0.0-rc5-46-g871ba2e5",
-			"Rev": "595bea022f077a9e17d7473b34fbaf1adaed9e43"
+			"Rev": "871ba2e58e24314d1fab4517a80410191ba5ad01"
 		},
 		{
 			"ImportPath": "github.com/opencontainers/runc/libcontainer/apparmor",
-			"Comment": "v1.0.0-rc4-221-g595bea02",
+			"Comment": "v1.0.0-rc5-46-g871ba2e5",
-			"Rev": "595bea022f077a9e17d7473b34fbaf1adaed9e43"
+			"Rev": "871ba2e58e24314d1fab4517a80410191ba5ad01"
 		},
 		{
 			"ImportPath": "github.com/opencontainers/runc/libcontainer/cgroups",
-			"Comment": "v1.0.0-rc4-221-g595bea02",
+			"Comment": "v1.0.0-rc5-46-g871ba2e5",
-			"Rev": "595bea022f077a9e17d7473b34fbaf1adaed9e43"
+			"Rev": "871ba2e58e24314d1fab4517a80410191ba5ad01"
 		},
 		{
 			"ImportPath": "github.com/opencontainers/runc/libcontainer/cgroups/fs",
-			"Comment": "v1.0.0-rc4-221-g595bea02",
+			"Comment": "v1.0.0-rc5-46-g871ba2e5",
-			"Rev": "595bea022f077a9e17d7473b34fbaf1adaed9e43"
+			"Rev": "871ba2e58e24314d1fab4517a80410191ba5ad01"
 		},
 		{
 			"ImportPath": "github.com/opencontainers/runc/libcontainer/cgroups/systemd",
-			"Comment": "v1.0.0-rc4-221-g595bea02",
+			"Comment": "v1.0.0-rc5-46-g871ba2e5",
-			"Rev": "595bea022f077a9e17d7473b34fbaf1adaed9e43"
+			"Rev": "871ba2e58e24314d1fab4517a80410191ba5ad01"
 		},
 		{
 			"ImportPath": "github.com/opencontainers/runc/libcontainer/configs",
-			"Comment": "v1.0.0-rc4-221-g595bea02",
+			"Comment": "v1.0.0-rc5-46-g871ba2e5",
-			"Rev": "595bea022f077a9e17d7473b34fbaf1adaed9e43"
+			"Rev": "871ba2e58e24314d1fab4517a80410191ba5ad01"
 		},
 		{
 			"ImportPath": "github.com/opencontainers/runc/libcontainer/configs/validate",
-			"Comment": "v1.0.0-rc4-221-g595bea02",
+			"Comment": "v1.0.0-rc5-46-g871ba2e5",
-			"Rev": "595bea022f077a9e17d7473b34fbaf1adaed9e43"
+			"Rev": "871ba2e58e24314d1fab4517a80410191ba5ad01"
 		},
 		{
 			"ImportPath": "github.com/opencontainers/runc/libcontainer/criurpc",
-			"Comment": "v1.0.0-rc4-221-g595bea02",
+			"Comment": "v1.0.0-rc5-46-g871ba2e5",
-			"Rev": "595bea022f077a9e17d7473b34fbaf1adaed9e43"
+			"Rev": "871ba2e58e24314d1fab4517a80410191ba5ad01"
 		},
 		{
 			"ImportPath": "github.com/opencontainers/runc/libcontainer/intelrdt",
-			"Comment": "v1.0.0-rc4-221-g595bea02",
+			"Comment": "v1.0.0-rc5-46-g871ba2e5",
-			"Rev": "595bea022f077a9e17d7473b34fbaf1adaed9e43"
+			"Rev": "871ba2e58e24314d1fab4517a80410191ba5ad01"
 		},
 		{
 			"ImportPath": "github.com/opencontainers/runc/libcontainer/keys",
-			"Comment": "v1.0.0-rc4-221-g595bea02",
+			"Comment": "v1.0.0-rc5-46-g871ba2e5",
-			"Rev": "595bea022f077a9e17d7473b34fbaf1adaed9e43"
+			"Rev": "871ba2e58e24314d1fab4517a80410191ba5ad01"
 		},
 		{
 			"ImportPath": "github.com/opencontainers/runc/libcontainer/mount",
-			"Comment": "v1.0.0-rc4-221-g595bea02",
+			"Comment": "v1.0.0-rc5-46-g871ba2e5",
-			"Rev": "595bea022f077a9e17d7473b34fbaf1adaed9e43"
+			"Rev": "871ba2e58e24314d1fab4517a80410191ba5ad01"
 		},
 		{
 			"ImportPath": "github.com/opencontainers/runc/libcontainer/seccomp",
-			"Comment": "v1.0.0-rc4-221-g595bea02",
+			"Comment": "v1.0.0-rc5-46-g871ba2e5",
-			"Rev": "595bea022f077a9e17d7473b34fbaf1adaed9e43"
+			"Rev": "871ba2e58e24314d1fab4517a80410191ba5ad01"
 		},
 		{
 			"ImportPath": "github.com/opencontainers/runc/libcontainer/stacktrace",
-			"Comment": "v1.0.0-rc4-221-g595bea02",
+			"Comment": "v1.0.0-rc5-46-g871ba2e5",
-			"Rev": "595bea022f077a9e17d7473b34fbaf1adaed9e43"
+			"Rev": "871ba2e58e24314d1fab4517a80410191ba5ad01"
 		},
 		{
 			"ImportPath": "github.com/opencontainers/runc/libcontainer/system",
-			"Comment": "v1.0.0-rc4-221-g595bea02",
+			"Comment": "v1.0.0-rc5-46-g871ba2e5",
-			"Rev": "595bea022f077a9e17d7473b34fbaf1adaed9e43"
+			"Rev": "871ba2e58e24314d1fab4517a80410191ba5ad01"
 		},
 		{
 			"ImportPath": "github.com/opencontainers/runc/libcontainer/user",
-			"Comment": "v1.0.0-rc4-221-g595bea02",
+			"Comment": "v1.0.0-rc5-46-g871ba2e5",
-			"Rev": "595bea022f077a9e17d7473b34fbaf1adaed9e43"
+			"Rev": "871ba2e58e24314d1fab4517a80410191ba5ad01"
 		},
 		{
 			"ImportPath": "github.com/opencontainers/runc/libcontainer/utils",
-			"Comment": "v1.0.0-rc4-221-g595bea02",
+			"Comment": "v1.0.0-rc5-46-g871ba2e5",
-			"Rev": "595bea022f077a9e17d7473b34fbaf1adaed9e43"
+			"Rev": "871ba2e58e24314d1fab4517a80410191ba5ad01"
 		},
 		{
 			"ImportPath": "github.com/opencontainers/runtime-spec/specs-go",

vendor/github.com/opencontainers/runc/libcontainer/cgroups/fs/apply_raw.go

@@ -161,7 +161,7 @@ func (m *Manager) Apply(pid int) (err error) {
 }
 
 func (m *Manager) Destroy() error {
-	if m.Cgroups.Paths != nil {
+	if m.Cgroups == nil || m.Cgroups.Paths != nil {
 		return nil
 	}
 	m.mu.Lock()

vendor/github.com/opencontainers/runc/libcontainer/cgroups/systemd/BUILD

@@ -64,6 +64,7 @@ go_library(
             "//vendor/github.com/opencontainers/runc/libcontainer/cgroups:go_default_library",
             "//vendor/github.com/opencontainers/runc/libcontainer/cgroups/fs:go_default_library",
             "//vendor/github.com/opencontainers/runc/libcontainer/configs:go_default_library",
+            "//vendor/github.com/sirupsen/logrus:go_default_library",
         ],
         "@io_bazel_rules_go//go/platform:nacl": [
             "//vendor/github.com/opencontainers/runc/libcontainer/cgroups:go_default_library",

vendor/github.com/opencontainers/runc/libcontainer/cgroups/systemd/apply_systemd.go

@@ -17,6 +17,7 @@ import (
 	"github.com/opencontainers/runc/libcontainer/cgroups"
 	"github.com/opencontainers/runc/libcontainer/cgroups/fs"
 	"github.com/opencontainers/runc/libcontainer/configs"
+	"github.com/sirupsen/logrus"
 )
 
 type Manager struct {
@@ -74,7 +75,8 @@ var (
 	hasStartTransientUnit           bool
 	hasStartTransientSliceUnit      bool
 	hasTransientDefaultDependencies bool
-	hasDelegate                     bool
+	hasDelegateScope                bool
+	hasDelegateSlice                bool
 )
 
 func newProp(name string, units interface{}) systemdDbus.Property {
@@ -149,12 +151,12 @@ func UseSystemd() bool {
 		theConn.StopUnit(scope, "replace", nil)
 
 		// Assume StartTransientUnit on a scope allows Delegate
-		hasDelegate = true
+		hasDelegateScope = true
-		dl := newProp("Delegate", true)
+		dlScope := newProp("Delegate", true)
-		if _, err := theConn.StartTransientUnit(scope, "replace", []systemdDbus.Property{dl}, nil); err != nil {
+		if _, err := theConn.StartTransientUnit(scope, "replace", []systemdDbus.Property{dlScope}, nil); err != nil {
 			if dbusError, ok := err.(dbus.Error); ok {
 				if strings.Contains(dbusError.Name, "org.freedesktop.DBus.Error.PropertyReadOnly") {
-					hasDelegate = false
+					hasDelegateScope = false
 				}
 			}
 		}
@@ -186,6 +188,22 @@ func UseSystemd() bool {
 			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(scope, "replace", nil)
 		theConn.StopUnit(slice, "replace", nil)
@@ -241,9 +259,16 @@ func (m *Manager) Apply(pid int) error {
 		properties = append(properties, newProp("PIDs", []uint32{uint32(pid)}))
 	}
 
-	if hasDelegate {
+	// Check if we can delegate. This is only supported on systemd versions 218 and above.
-		// This is only supported on systemd versions 218 and above.
+	if strings.HasSuffix(unitName, ".slice") {
-		properties = append(properties, newProp("Delegate", true))
+		if hasDelegateSlice {
+			// systemd 237 and above no longer allows delegation on a slice
+			properties = append(properties, newProp("Delegate", true))
+		}
+	} else {
+		if hasDelegateScope {
+			properties = append(properties, newProp("Delegate", true))
+		}
 	}
 
 	// Always enable accounting, this gets us the same behaviour as the fs implementation,
@@ -295,13 +320,17 @@ func (m *Manager) Apply(pid int) error {
 		}
 	}
 
-	statusChan := make(chan string)
+	statusChan := make(chan string, 1)
-	if _, err := theConn.StartTransientUnit(unitName, "replace", properties, statusChan); err != nil && !isUnitExists(err) {
+	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
 	}
 
-	<-statusChan
-
 	if err := joinCgroups(c, pid); err != nil {
 		return err
 	}

vendor/github.com/opencontainers/runc/libcontainer/configs/validate/rootless.go

@@ -49,7 +49,7 @@ func rootlessMappings(config *configs.Config) error {
 		return fmt.Errorf("rootless containers requires at least one UID mapping")
 	}
 	if len(config.GidMappings) == 0 {
-		return fmt.Errorf("rootless containers requires at least one UID mapping")
+		return fmt.Errorf("rootless containers requires at least one GID mapping")
 	}
 
 	return nil

vendor/github.com/opencontainers/runc/libcontainer/container_linux.go

@@ -377,10 +377,6 @@ func (c *linuxContainer) start(process *Process, isInit bool) error {
 				}
 			}
 		}
-	} else {
-		c.state = &runningState{
-			c: c,
-		}
 	}
 	return nil
 }
@@ -1801,8 +1797,7 @@ func (c *linuxContainer) bootstrapData(cloneFlags uintptr, nsMaps map[configs.Na
 					Value: []byte(c.newgidmapPath),
 				})
 			}
-			// The following only applies if we are root.
+			if requiresRootOrMappingTool(c.config) {
-			if !c.config.Rootless {
 				// check if we have CAP_SETGID to setgroup properly
 				pid, err := capability.NewPid(0)
 				if err != nil {
@@ -1847,3 +1842,10 @@ func ignoreTerminateErrors(err error) error {
 	}
 	return err
 }
+
+func requiresRootOrMappingTool(c *configs.Config) bool {
+	gidMap := []configs.IDMap{
+		{ContainerID: 0, HostID: os.Getegid(), Size: 1},
+	}
+	return !reflect.DeepEqual(c.GidMappings, gidMap)
+}

vendor/github.com/opencontainers/runc/libcontainer/message_linux.go

@@ -77,13 +77,13 @@ func (msg *Boolmsg) Serialize() []byte {
 	native.PutUint16(buf[0:2], uint16(msg.Len()))
 	native.PutUint16(buf[2:4], msg.Type)
 	if msg.Value {
-		buf[4] = 1
+		native.PutUint32(buf[4:8], uint32(1))
 	} else {
-		buf[4] = 0
+		native.PutUint32(buf[4:8], uint32(0))
 	}
 	return buf
 }
 
 func (msg *Boolmsg) Len() int {
-	return unix.NLA_HDRLEN + 1
+	return unix.NLA_HDRLEN + 4 // alignment
 }

vendor/github.com/opencontainers/runc/libcontainer/rootfs_linux.go

@@ -46,7 +46,6 @@ func prepareRootfs(pipe io.ReadWriter, iConfig *initConfig) (err error) {
 		return newSystemErrorWithCause(err, "preparing rootfs")
 	}
 
-	setupDev := needsSetupDev(config)
 	for _, m := range config.Mounts {
 		for _, precmd := range m.PremountCmds {
 			if err := mountCmd(precmd); err != nil {
@@ -65,6 +64,8 @@ func prepareRootfs(pipe io.ReadWriter, iConfig *initConfig) (err error) {
 		}
 	}
 
+	setupDev := needsSetupDev(config)
+
 	if setupDev {
 		if err := createDevices(config); err != nil {
 			return newSystemErrorWithCause(err, "creating device nodes")
@@ -778,10 +779,10 @@ func remountReadonly(m *configs.Mount) error {
 // mounts ( proc/kcore ).
 // For files, maskPath bind mounts /dev/null over the top of the specified path.
 // For directories, maskPath mounts read-only tmpfs over the top of the specified path.
-func maskPath(path string) error {
+func maskPath(path string, mountLabel string) error {
 	if err := unix.Mount("/dev/null", path, "", unix.MS_BIND, ""); err != nil && !os.IsNotExist(err) {
 		if err == unix.ENOTDIR {
-			return unix.Mount("tmpfs", path, "tmpfs", unix.MS_RDONLY, "")
+			return unix.Mount("tmpfs", path, "tmpfs", unix.MS_RDONLY, label.FormatMountLabel("", mountLabel))
 		}
 		return err
 	}

vendor/github.com/opencontainers/runc/libcontainer/standard_init_linux.go

@@ -110,7 +110,7 @@ func (l *linuxStandardInit) Init() error {
 		}
 	}
 	for _, path := range l.config.Config.MaskPaths {
-		if err := maskPath(path); err != nil {
+		if err := maskPath(path, l.config.Config.MountLabel); err != nil {
 			return err
 		}
 	}

vendor/github.com/opencontainers/runc/libcontainer/user/BUILD

@@ -27,6 +27,9 @@ go_library(
         "@io_bazel_rules_go//go/platform:solaris": [
             "lookup_unix.go",
         ],
+        "@io_bazel_rules_go//go/platform:windows": [
+            "lookup_windows.go",
+        ],
         "//conditions:default": [],
     }),
     importpath = "github.com/opencontainers/runc/libcontainer/user",

vendor/github.com/opencontainers/runc/libcontainer/user/lookup.go

@@ -12,84 +12,30 @@ var (
 	ErrNoGroupEntries  = errors.New("no matching entries in group file")
 )
 
-func lookupUser(filter func(u User) bool) (User, error) {
-	// Get operating system-specific passwd reader-closer.
-	passwd, err := GetPasswd()
-	if err != nil {
-		return User{}, err
-	}
-	defer passwd.Close()
-
-	// Get the users.
-	users, err := ParsePasswdFilter(passwd, filter)
-	if err != nil {
-		return User{}, err
-	}
-
-	// No user entries found.
-	if len(users) == 0 {
-		return User{}, ErrNoPasswdEntries
-	}
-
-	// Assume the first entry is the "correct" one.
-	return users[0], nil
-}
-
 // LookupUser looks up a user by their username in /etc/passwd. If the user
 // cannot be found (or there is no /etc/passwd file on the filesystem), then
 // LookupUser returns an error.
 func LookupUser(username string) (User, error) {
-	return lookupUser(func(u User) bool {
+	return lookupUser(username)
-		return u.Name == username
-	})
 }
 
 // LookupUid looks up a user by their user id in /etc/passwd. If the user cannot
 // be found (or there is no /etc/passwd file on the filesystem), then LookupId
 // returns an error.
 func LookupUid(uid int) (User, error) {
-	return lookupUser(func(u User) bool {
+	return lookupUid(uid)
-		return u.Uid == uid
-	})
-}
-
-func lookupGroup(filter func(g Group) bool) (Group, error) {
-	// Get operating system-specific group reader-closer.
-	group, err := GetGroup()
-	if err != nil {
-		return Group{}, err
-	}
-	defer group.Close()
-
-	// Get the users.
-	groups, err := ParseGroupFilter(group, filter)
-	if err != nil {
-		return Group{}, err
-	}
-
-	// No user entries found.
-	if len(groups) == 0 {
-		return Group{}, ErrNoGroupEntries
-	}
-
-	// Assume the first entry is the "correct" one.
-	return groups[0], nil
 }
 
 // LookupGroup looks up a group by its name in /etc/group. If the group cannot
 // be found (or there is no /etc/group file on the filesystem), then LookupGroup
 // returns an error.
 func LookupGroup(groupname string) (Group, error) {
-	return lookupGroup(func(g Group) bool {
+	return lookupGroup(groupname)
-		return g.Name == groupname
-	})
 }
 
 // LookupGid looks up a group by its group id in /etc/group. If the group cannot
 // be found (or there is no /etc/group file on the filesystem), then LookupGid
 // returns an error.
 func LookupGid(gid int) (Group, error) {
-	return lookupGroup(func(g Group) bool {
+	return lookupGid(gid)
-		return g.Gid == gid
-	})
 }

vendor/github.com/opencontainers/runc/libcontainer/user/lookup_unix.go

@@ -15,6 +15,76 @@ const (
 	unixGroupPath  = "/etc/group"
 )
 
+func lookupUser(username string) (User, error) {
+	return lookupUserFunc(func(u User) bool {
+		return u.Name == username
+	})
+}
+
+func lookupUid(uid int) (User, error) {
+	return lookupUserFunc(func(u User) bool {
+		return u.Uid == uid
+	})
+}
+
+func lookupUserFunc(filter func(u User) bool) (User, error) {
+	// Get operating system-specific passwd reader-closer.
+	passwd, err := GetPasswd()
+	if err != nil {
+		return User{}, err
+	}
+	defer passwd.Close()
+
+	// Get the users.
+	users, err := ParsePasswdFilter(passwd, filter)
+	if err != nil {
+		return User{}, err
+	}
+
+	// No user entries found.
+	if len(users) == 0 {
+		return User{}, ErrNoPasswdEntries
+	}
+
+	// Assume the first entry is the "correct" one.
+	return users[0], nil
+}
+
+func lookupGroup(groupname string) (Group, error) {
+	return lookupGroupFunc(func(g Group) bool {
+		return g.Name == groupname
+	})
+}
+
+func lookupGid(gid int) (Group, error) {
+	return lookupGroupFunc(func(g Group) bool {
+		return g.Gid == gid
+	})
+}
+
+func lookupGroupFunc(filter func(g Group) bool) (Group, error) {
+	// Get operating system-specific group reader-closer.
+	group, err := GetGroup()
+	if err != nil {
+		return Group{}, err
+	}
+	defer group.Close()
+
+	// Get the users.
+	groups, err := ParseGroupFilter(group, filter)
+	if err != nil {
+		return Group{}, err
+	}
+
+	// No user entries found.
+	if len(groups) == 0 {
+		return Group{}, ErrNoGroupEntries
+	}
+
+	// Assume the first entry is the "correct" one.
+	return groups[0], nil
+}
+
 func GetPasswdPath() (string, error) {
 	return unixPasswdPath, nil
 }

vendor/github.com/opencontainers/runc/libcontainer/user/lookup_windows.go

@@ -0,0 +1,40 @@
+// +build windows
+
+package user
+
+import (
+	"fmt"
+	"os/user"
+)
+
+func lookupUser(username string) (User, error) {
+	u, err := user.Lookup(username)
+	if err != nil {
+		return User{}, err
+	}
+	return userFromOS(u)
+}
+
+func lookupUid(uid int) (User, error) {
+	u, err := user.LookupId(fmt.Sprintf("%d", uid))
+	if err != nil {
+		return User{}, err
+	}
+	return userFromOS(u)
+}
+
+func lookupGroup(groupname string) (Group, error) {
+	g, err := user.LookupGroup(groupname)
+	if err != nil {
+		return Group{}, err
+	}
+	return groupFromOS(g)
+}
+
+func lookupGid(gid int) (Group, error) {
+	g, err := user.LookupGroupId(fmt.Sprintf("%d", gid))
+	if err != nil {
+		return Group{}, err
+	}
+	return groupFromOS(g)
+}

vendor/github.com/opencontainers/runc/libcontainer/user/user.go

@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"io"
 	"os"
+	"os/user"
 	"strconv"
 	"strings"
 )
@@ -28,6 +29,28 @@ type User struct {
 	Shell string
 }
 
+// userFromOS converts an os/user.(*User) to local User
+//
+// (This does not include Pass, Shell or Gecos)
+func userFromOS(u *user.User) (User, error) {
+	newUser := User{
+		Name: u.Username,
+		Home: u.HomeDir,
+	}
+	id, err := strconv.Atoi(u.Uid)
+	if err != nil {
+		return newUser, err
+	}
+	newUser.Uid = id
+
+	id, err = strconv.Atoi(u.Gid)
+	if err != nil {
+		return newUser, err
+	}
+	newUser.Gid = id
+	return newUser, nil
+}
+
 type Group struct {
 	Name string
 	Pass string
@@ -35,6 +58,23 @@ type Group struct {
 	List []string
 }
 
+// groupFromOS converts an os/user.(*Group) to local Group
+//
+// (This does not include Pass, Shell or Gecos)
+func groupFromOS(g *user.Group) (Group, error) {
+	newGroup := Group{
+		Name: g.Name,
+	}
+
+	id, err := strconv.Atoi(g.Gid)
+	if err != nil {
+		return newGroup, err
+	}
+	newGroup.Gid = id
+
+	return newGroup, nil
+}
+
 func parseLine(line string, v ...interface{}) {
 	if line == "" {
 		return