create temporary dir for overlayfs not in __child

internal/app/wwctl/container/exec/child/main.go

@@ -32,14 +32,20 @@ func CobraRunE(cmd *cobra.Command, args []string) error {
 		os.Exit(1)
 	}
 	var err error
-	tempDir := ""
 	// check for valid mount points
 	lowerObjects := checkMountPoints(containerName, binds)
 	if len(lowerObjects) != 0 {
+		if tempDir == "" {
+			tempDir, err = os.MkdirTemp(buildconfig.TMPDIR(), "overlay")
+			if err != nil {
+				wwlog.Warn("couldn't create temp dir for overlay", err)
+				lowerObjects = []string{}
+				tempDir = ""
+			}
+		}
 		// need to create a overlay, where the lower layer contains
 		// the missing mount points
-		tempDir, err = os.MkdirTemp(buildconfig.TMPDIR(), "overlay")
-		if err == nil {
+		if tempDir != "" {
 			wwlog.Verbose("for ephermal mount use tempdir %s", tempDir)
 			// ignore errors as we are doomed if a tmp dir couldn't be written
 			_ = os.Mkdir(path.Join(tempDir, "work"), os.ModePerm)
@@ -61,19 +67,8 @@ func CobraRunE(cmd *cobra.Command, args []string) error {
 					}
 					defer desc.Close()
 				}
-
 			}
-		} else {
-			wwlog.Warn("couldn't create temp dir for overlay", err)
-			lowerObjects = []string{}
 		}
-		/*
-			\TODO check why defer isn't called at exit
-			defer func() {
-				fmt.Println("defer called")
-				_ = os.RemoveAll(tempDir)
-			}()
-		*/
 	}
 	containerPath := container.RootFsDir(containerName)
 	err = syscall.Mount("", "/", "", syscall.MS_PRIVATE|syscall.MS_REC, "")
@@ -148,15 +143,10 @@ func CobraRunE(cmd *cobra.Command, args []string) error {
 	os.Setenv("PATH", "/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin")
 	os.Setenv("HISTFILE", "/dev/null")
 
-	err = syscall.Exec(args[1], args[1:], os.Environ())
-	fmt.Println("After exec")
-	_ = os.RemoveAll(tempDir)
-	if err != nil {
-		wwlog.Error("%s", err)
-
-		os.Exit(1)
-	}
-
+	_ = syscall.Exec(args[1], args[1:], os.Environ())
+	/*
+		Exec replaces the actual program, so nothing to do here afterwards
+	*/
 	return nil
 }
 

internal/app/wwctl/container/exec/child/root.go

@@ -5,17 +5,19 @@ import "github.com/spf13/cobra"
 var (
 	baseCmd = &cobra.Command{
 		DisableFlagsInUseLine: true,
-		Use:                "__child",
-		Hidden:             true,
-		RunE:               CobraRunE,
-		Args:               cobra.MinimumNArgs(1),
-		FParseErrWhitelist: cobra.FParseErrWhitelist{UnknownFlags: true},
+		Use:                   "__child",
+		Hidden:                true,
+		RunE:                  CobraRunE,
+		Args:                  cobra.MinimumNArgs(1),
+		FParseErrWhitelist:    cobra.FParseErrWhitelist{UnknownFlags: true},
 	}
-	binds []string
+	binds   []string
+	tempDir string
 )
 
 func init() {
-	baseCmd.PersistentFlags().StringArrayVarP(&binds, "bind", "b", []string{}, "bind points")
+	baseCmd.Flags().StringArrayVarP(&binds, "bind", "b", []string{}, "bind points")
+	baseCmd.Flags().StringVar(&tempDir, "tempdir", "", "tempdir")
 }
 
 // GetRootCommand returns the root cobra.Command for the application.

internal/app/wwctl/container/exec/main.go

@@ -11,6 +11,7 @@ import (
 	"syscall"
 	"time"
 
+	"github.com/hpcng/warewulf/internal/pkg/buildconfig"
 	"github.com/hpcng/warewulf/internal/pkg/container"
 	"github.com/hpcng/warewulf/internal/pkg/util"
 	"github.com/hpcng/warewulf/internal/pkg/wwlog"
@@ -21,9 +22,22 @@ import (
 fork off a process with a new PID space
 */
 func runContainedCmd(args []string) error {
+	var err error
+	if tempDir == "" {
+		tempDir, err = os.MkdirTemp(buildconfig.TMPDIR(), "overlay")
+		if err != nil {
+			wwlog.Warn("couldn't create temp dir for overlay", err)
+		}
+		defer func() {
+			err = os.RemoveAll(tempDir)
+			if err != nil {
+				wwlog.Warn("Couldn't remove temp dir for ephermal mounts:", err)
+			}
+		}()
+	}
 	logStr := fmt.Sprint(wwlog.GetLogLevel())
 	wwlog.Verbose("Running contained command: %s", args[1:])
-	c := exec.Command("/proc/self/exe", append([]string{"--loglevel", logStr, "container", "exec", "__child"}, args...)...)
+	c := exec.Command("/proc/self/exe", append([]string{"--loglevel", logStr, "--tempdir", tempDir, "container", "exec", "__child"}, args...)...)
 
 	c.SysProcAttr = &syscall.SysProcAttr{
 		Cloneflags: syscall.CLONE_NEWUTS | syscall.CLONE_NEWPID | syscall.CLONE_NEWNS,

internal/app/wwctl/container/exec/root.go

@@ -27,12 +27,14 @@ var (
 	}
 	SyncUser bool
 	binds    []string
+	tempDir  string
 )
 
 func init() {
 	baseCmd.AddCommand(child.GetCommand())
 	baseCmd.PersistentFlags().StringArrayVarP(&binds, "bind", "b", []string{}, "Bind a local path into the container (must exist)")
 	baseCmd.PersistentFlags().BoolVar(&SyncUser, "syncuser", false, "Synchronize UIDs/GIDs from host to container")
+	baseCmd.PersistentFlags().StringVar(&tempDir, "tempdir", "", "Use tempdir for constructing the overlay fs (only used if mount points don't exist in container)")
 }
 
 // GetRootCommand returns the root cobra.Command for the application.