Add nvidia-ctk runtime configure command

This change adds a `runtime configure` command to the nvidia-ctk CLI. This
command is currently limited to configuring the docker config on the
system by modifying the daemon.json config file associated with docker.

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

cmd/nvidia-ctk/README.md

@@ -1,3 +1,17 @@
 # NVIDIA Container Toolkit CLI
 
 The NVIDIA Container Toolkit CLI `nvidia-ctk` provides a number of utilities that are useful for working with the NVIDIA Container Toolkit.
+
+## Functionality
+
+### Configure runtimes
+
+The `runtime` command of the `nvidia-ctk` CLI provides a set of utilities to related to the configuration
+and management of supported container engines.
+
+For example, running the following command:
+```bash
+nvidia-ctk runtime configure --set-as-default
+```
+will ensure that the NVIDIA Container Runtime is added as the default runtime to the default container
+engine.

cmd/nvidia-ctk/main.go

@@ -20,6 +20,7 @@ import (
 	"os"
 
 	"github.com/NVIDIA/nvidia-container-toolkit/cmd/nvidia-ctk/hook"
+	"github.com/NVIDIA/nvidia-container-toolkit/cmd/nvidia-ctk/runtime"
 	"github.com/NVIDIA/nvidia-container-toolkit/internal/info"
 	log "github.com/sirupsen/logrus"
 	cli "github.com/urfave/cli/v2"
@@ -70,6 +71,7 @@ func main() {
 	// Define the subcommands
 	c.Commands = []*cli.Command{
 		hook.NewCommand(logger),
+		runtime.NewCommand(logger),
 	}
 
 	// Run the CLI

cmd/nvidia-ctk/runtime/configure/configure.go

@@ -0,0 +1,154 @@
+/**
+# 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 configure
+
+import (
+	"encoding/json"
+	"fmt"
+	"os"
+
+	"github.com/NVIDIA/nvidia-container-toolkit/cmd/nvidia-ctk/runtime/nvidia"
+	"github.com/NVIDIA/nvidia-container-toolkit/internal/config/docker"
+	"github.com/sirupsen/logrus"
+	"github.com/urfave/cli/v2"
+)
+
+const (
+	defaultRuntime = "docker"
+
+	defaultDockerConfigFilePath = "/etc/docker/daemon.json"
+)
+
+type command struct {
+	logger *logrus.Logger
+}
+
+// NewCommand constructs an configure command with the specified logger
+func NewCommand(logger *logrus.Logger) *cli.Command {
+	c := command{
+		logger: logger,
+	}
+	return c.build()
+}
+
+// config defines the options that can be set for the CLI through config files,
+// environment variables, or command line config
+type config struct {
+	dryRun         bool
+	runtime        string
+	configFilePath string
+	nvidiaOptions  nvidia.Options
+}
+
+func (m command) build() *cli.Command {
+	// Create a config struct to hold the parsed environment variables or command line flags
+	config := config{}
+
+	// Create the 'configure' command
+	configure := cli.Command{
+		Name:  "configure",
+		Usage: "Add a runtime to the specified container engine",
+		Action: func(c *cli.Context) error {
+			return m.configureWrapper(c, &config)
+		},
+	}
+
+	configure.Flags = []cli.Flag{
+		&cli.BoolFlag{
+			Name:        "dry-run",
+			Usage:       "update the runtime configuration as required but don't write changes to disk",
+			Destination: &config.dryRun,
+		},
+		&cli.StringFlag{
+			Name:        "runtime",
+			Usage:       "the target runtime engine. One of [docker]",
+			Value:       defaultRuntime,
+			Destination: &config.runtime,
+		},
+		&cli.StringFlag{
+			Name:        "config",
+			Usage:       "path to the config file for the target runtime",
+			Destination: &config.configFilePath,
+		},
+		&cli.StringFlag{
+			Name:        "nvidia-runtime-name",
+			Usage:       "specify the name of the NVIDIA runtime that will be added",
+			Value:       nvidia.RuntimeName,
+			Destination: &config.nvidiaOptions.RuntimeName,
+		},
+		&cli.StringFlag{
+			Name:        "runtime-path",
+			Usage:       "specify the path to the NVIDIA runtime executable",
+			Value:       nvidia.RuntimeExecutable,
+			Destination: &config.nvidiaOptions.RuntimePath,
+		},
+		&cli.BoolFlag{
+			Name:        "set-as-default",
+			Usage:       "set the specified runtime as the default runtime",
+			Destination: &config.nvidiaOptions.SetAsDefault,
+		},
+	}
+
+	return &configure
+}
+
+func (m command) configureWrapper(c *cli.Context, config *config) error {
+	switch config.runtime {
+	case "docker":
+		return m.configureDocker(c, config)
+	}
+
+	return fmt.Errorf("unrecognized runtime '%v'", config.runtime)
+}
+
+// configureDocker updates the docker config to enable the NVIDIA Container Runtime
+func (m command) configureDocker(c *cli.Context, config *config) error {
+	configFilePath := config.configFilePath
+	if configFilePath == "" {
+		configFilePath = defaultDockerConfigFilePath
+	}
+
+	cfg, err := docker.LoadConfig(configFilePath)
+	if err != nil {
+		return fmt.Errorf("unable to load config: %v", err)
+	}
+
+	defaultRuntime := config.nvidiaOptions.DefaultRuntime()
+	runtimeConfig := config.nvidiaOptions.Runtime().DockerRuntimesConfig()
+	err = docker.UpdateConfig(cfg, defaultRuntime, runtimeConfig)
+	if err != nil {
+		return fmt.Errorf("unable to update config: %v", err)
+	}
+
+	if config.dryRun {
+		output, err := json.MarshalIndent(cfg, "", "    ")
+		if err != nil {
+			return fmt.Errorf("unable to convert to JSON: %v", err)
+		}
+		os.Stdout.WriteString(fmt.Sprintf("%s\n", output))
+		return nil
+	}
+	err = docker.FlushConfig(cfg, configFilePath)
+	if err != nil {
+		return fmt.Errorf("unable to flush config: %v", err)
+	}
+
+	m.logger.Infof("Wrote updated config to %v", configFilePath)
+	m.logger.Infof("It is recommended that the docker daemon be restarted.")
+
+	return nil
+}

cmd/nvidia-ctk/runtime/nvidia/nvidia.go

@@ -0,0 +1,75 @@
+/*
+# 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 nvidia
+
+const (
+	// RuntimeName is the default name to use in configs for the NVIDIA Container Runtime
+	RuntimeName = "nvidia"
+	// RuntimeExecutable is the default NVIDIA Container Runtime executable file name
+	RuntimeExecutable = "nvidia-container-runtime"
+)
+
+// Options specifies the options for the NVIDIA Container Runtime w.r.t a container engine such as docker.
+type Options struct {
+	SetAsDefault bool
+	RuntimeName  string
+	RuntimePath  string
+}
+
+// Runtime defines an NVIDIA runtime with a name and a executable
+type Runtime struct {
+	Name string
+	Path string
+}
+
+// DefaultRuntime returns the default runtime for the configured options.
+// If the configuration is invalid or the default runtimes should not be set
+// the empty string is returned.
+func (o Options) DefaultRuntime() string {
+	if !o.SetAsDefault {
+		return ""
+	}
+
+	return o.RuntimeName
+}
+
+// Runtime creates a runtime struct based on the options.
+func (o Options) Runtime() Runtime {
+	path := o.RuntimePath
+
+	if o.RuntimePath == "" {
+		path = RuntimeExecutable
+	}
+
+	r := Runtime{
+		Name: o.RuntimeName,
+		Path: path,
+	}
+
+	return r
+}
+
+// DockerRuntimesConfig generatest the expected docker config for the specified runtime
+func (r Runtime) DockerRuntimesConfig() map[string]interface{} {
+	runtimes := make(map[string]interface{})
+	runtimes[r.Name] = map[string]interface{}{
+		"path": r.Path,
+		"args": []string{},
+	}
+
+	return runtimes
+}

cmd/nvidia-ctk/runtime/runtime.go

@@ -0,0 +1,49 @@
+/**
+# 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 runtime
+
+import (
+	"github.com/NVIDIA/nvidia-container-toolkit/cmd/nvidia-ctk/runtime/configure"
+	"github.com/sirupsen/logrus"
+	"github.com/urfave/cli/v2"
+)
+
+type runtimeCommand struct {
+	logger *logrus.Logger
+}
+
+// NewCommand constructs a runtime command with the specified logger
+func NewCommand(logger *logrus.Logger) *cli.Command {
+	c := runtimeCommand{
+		logger: logger,
+	}
+	return c.build()
+}
+
+func (m runtimeCommand) build() *cli.Command {
+	// Create the 'runtime' command
+	runtime := cli.Command{
+		Name:  "runtime",
+		Usage: "A collection of runtime-related utilities for the NVIDIA Container Toolkit",
+	}
+
+	runtime.Subcommands = []*cli.Command{
+		configure.NewCommand(m.logger),
+	}
+
+	return &runtime
+}