Allow for customizing the path to ldconfig

Since the `createContainer` `runc` hook runs with the environment that
the container's config.json specifies, the path to `ldconfig` may not be
easily resolvable if the host environment differs enough from the
container (e.g. on a NixOS host where all binaries are under hashed
paths in /nix/store with an Ubuntu container whose PATH contains
FHS-style paths such as /bin and /usr/bin). This change allows for
specifying exactly where ldconfig comes from.

Signed-off-by: Jared Baur <jaredbaur@fastmail.com>

cmd/nvidia-ctk/cdi/generate/generate.go

@@ -48,6 +48,7 @@ type options struct {
 	driverRoot         string
 	devRoot            string
 	nvidiaCTKPath      string
+	ldconfigPath       string
 	mode               string
 	vendor             string
 	class              string
@@ -129,6 +130,11 @@ func (m command) build() *cli.Command {
 			Usage:       "Specify the path to use for the nvidia-ctk in the generated CDI specification. If this is left empty, the path will be searched.",
 			Destination: &opts.nvidiaCTKPath,
 		},
+		&cli.StringFlag{
+			Name:        "ldconfig-path",
+			Usage:       "Specify the path to use for ldconfig in the generated CDI specification",
+			Destination: &opts.ldconfigPath,
+		},
 		&cli.StringFlag{
 			Name:        "vendor",
 			Aliases:     []string{"cdi-vendor"},
@@ -245,6 +251,7 @@ func (m command) generateSpec(opts *options) (spec.Interface, error) {
 		nvcdi.WithDriverRoot(opts.driverRoot),
 		nvcdi.WithDevRoot(opts.devRoot),
 		nvcdi.WithNVIDIACTKPath(opts.nvidiaCTKPath),
+		nvcdi.WithLdconfigPath(opts.ldconfigPath),
 		nvcdi.WithDeviceNamer(deviceNamer),
 		nvcdi.WithMode(opts.mode),
 		nvcdi.WithLibrarySearchPaths(opts.librarySearchPaths.Value()),

cmd/nvidia-ctk/hook/update-ldcache/update-ldcache.go

@@ -36,6 +36,7 @@ type command struct {
 
 type options struct {
 	folders       cli.StringSlice
+	ldconfigPath  string
 	containerSpec string
 }
 
@@ -66,6 +67,12 @@ func (m command) build() *cli.Command {
 			Usage:       "Specify a folder to add to /etc/ld.so.conf before updating the ld cache",
 			Destination: &cfg.folders,
 		},
+		&cli.StringFlag{
+			Name:        "ldconfig-path",
+			Usage:       "Specify the path to the ldconfig program",
+			Destination: &cfg.ldconfigPath,
+			DefaultText: "/sbin/ldconfig",
+		},
 		&cli.StringFlag{
 			Name:        "container-spec",
 			Usage:       "Specify the path to the OCI container spec. If empty or '-' the spec will be read from STDIN",
@@ -87,7 +94,7 @@ func (m command) run(c *cli.Context, cfg *options) error {
 		return fmt.Errorf("failed to determined container root: %v", err)
 	}
 
-	ldconfigPath := m.resolveLDConfigPath("/sbin/ldconfig")
+	ldconfigPath := m.resolveLDConfigPath(cfg.ldconfigPath)
 	args := []string{filepath.Base(ldconfigPath)}
 	if containerRoot != "" {
 		args = append(args, "-r", containerRoot)