Create .so symlinks for driver libraries in container

This change adds an opt-in feature for creating .so symlinks to
all injected driver files in a contianer.

If features.dot-so-symlinks = true is set in the config.toml, the creation
of symlinks for driver files is enabled. This can also be triggered on a
per-container basis using the envvar NVIDIA_DOT_SO_SYMLINKS=enabled.

Signed-off-by: Evan Lezar <elezar@nvidia.com>

cmd/nvidia-ctk/hook/create-dot-so-symlinks/create-dot-so-symlinks.go

@@ -0,0 +1,115 @@
+/**
+# Copyright (c) 2022, NVIDIA CORPORATION.  All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+**/
+
+package dotsosymlinks
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"github.com/urfave/cli/v2"
+
+	"github.com/NVIDIA/nvidia-container-toolkit/internal/logger"
+	"github.com/NVIDIA/nvidia-container-toolkit/internal/lookup"
+	"github.com/NVIDIA/nvidia-container-toolkit/internal/oci"
+)
+
+type command struct {
+	logger logger.Interface
+}
+
+type config struct {
+	containerSpec string
+	driverVersion string
+}
+
+// NewCommand constructs a hook command with the specified logger
+func NewCommand(logger logger.Interface) *cli.Command {
+	c := command{
+		logger: logger,
+	}
+	return c.build()
+}
+
+// build
+func (m command) build() *cli.Command {
+	cfg := config{}
+
+	// Create the '' command
+	c := cli.Command{
+		Name:  "create-dot-so-symlinks",
+		Usage: "A hook to create .so symlinks in the container.",
+		Action: func(c *cli.Context) error {
+			return m.run(c, &cfg)
+		},
+	}
+
+	c.Flags = []cli.Flag{
+		&cli.StringFlag{
+			Name:        "container-spec",
+			Usage:       "Specify the path to the OCI container spec. If empty or '-' the spec will be read from STDIN",
+			Destination: &cfg.containerSpec,
+		},
+		&cli.StringFlag{
+			Name:        "driver-version",
+			Usage:       "specify the driver version for which the symlinks are to be created. This assumes driver libraries have the .so.`VERSION` suffix.",
+			Destination: &cfg.driverVersion,
+			Required:    true,
+		},
+	}
+
+	return &c
+}
+
+func (m command) run(c *cli.Context, cfg *config) error {
+	s, err := oci.LoadContainerState(cfg.containerSpec)
+	if err != nil {
+		return fmt.Errorf("failed to load container state: %v", err)
+	}
+
+	containerRoot, err := s.GetContainerRoot()
+	if err != nil {
+		return fmt.Errorf("failed to determined container root: %v", err)
+	}
+
+	locator := lookup.NewLibraryLocator(
+		lookup.WithLogger(m.logger),
+		lookup.WithRoot(containerRoot),
+		lookup.WithOptional(true),
+	)
+	libs, err := locator.Locate("*.so." + cfg.driverVersion)
+	if err != nil {
+		return fmt.Errorf("failed to locate libraries for driver version %v: %v", cfg.driverVersion, err)
+	}
+
+	for _, lib := range libs {
+		if !strings.HasSuffix(lib, ".so."+cfg.driverVersion) {
+			continue
+		}
+		libSoPath := strings.TrimSuffix(lib, "."+cfg.driverVersion)
+		libSoXPaths, err := filepath.Glob(libSoPath + ".[0-9]")
+		if len(libSoXPaths) != 1 || err != nil {
+			continue
+		}
+		err = os.Symlink(filepath.Base(libSoXPaths[0]), libSoPath)
+		if err != nil {
+			continue
+		}
+	}
+	return nil
+}

cmd/nvidia-ctk/hook/hook.go

@@ -22,6 +22,7 @@ import (
 
 	"github.com/urfave/cli/v2"
 
+	createdotsosymlinks "github.com/NVIDIA/nvidia-container-toolkit/cmd/nvidia-ctk/hook/create-dot-so-symlinks"
 	symlinks "github.com/NVIDIA/nvidia-container-toolkit/cmd/nvidia-ctk/hook/create-symlinks"
 	ldcache "github.com/NVIDIA/nvidia-container-toolkit/cmd/nvidia-ctk/hook/update-ldcache"
 )
@@ -50,6 +51,7 @@ func (m hookCommand) build() *cli.Command {
 		ldcache.NewCommand(m.logger),
 		symlinks.NewCommand(m.logger),
 		chmod.NewCommand(m.logger),
+		createdotsosymlinks.NewCommand(m.logger),
 	}
 
 	return &hook