nvidia-container-toolkit/internal/config/config.go

/**
# 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 config

import (
	"fmt"
	"io"
	"os"
	"path"
	"path/filepath"

	"github.com/NVIDIA/nvidia-container-toolkit/internal/lookup"
	"github.com/pelletier/go-toml"
	"github.com/sirupsen/logrus"
)

const (
	configOverride = "XDG_CONFIG_HOME"
	configFilePath = "nvidia-container-runtime/config.toml"

	nvidiaContainerRuntimeHookExecutable  = "nvidia-container-runtime-hook"
	nvidiaContainerRuntimeHookDefaultPath = "/usr/bin/nvidia-container-runtime-hook"
)

var (
	// DefaultExecutableDir specifies the default path to use for executables if they cannot be located in the path.
	DefaultExecutableDir = "/usr/bin"

	// NVIDIAContainerRuntimeHookExecutable is the executable name for the NVIDIA Container Runtime Hook
	NVIDIAContainerRuntimeHookExecutable = "nvidia-container-runtime-hook"
	// NVIDIAContainerToolkitExecutable is the executable name for the NVIDIA Container Toolkit (an alias for the NVIDIA Container Runtime Hook)
	NVIDIAContainerToolkitExecutable = "nvidia-container-toolkit"

	configDir = "/etc/"
)

// Config represents the contents of the config.toml file for the NVIDIA Container Toolkit
// Note: This is currently duplicated by the HookConfig in cmd/nvidia-container-toolkit/hook_config.go
type Config struct {
	AcceptEnvvarUnprivileged bool `toml:"accept-nvidia-visible-devices-envvar-when-unprivileged"`

	NVIDIAContainerCLIConfig         ContainerCLIConfig `toml:"nvidia-container-cli"`
	NVIDIACTKConfig                  CTKConfig          `toml:"nvidia-ctk"`
	NVIDIAContainerRuntimeConfig     RuntimeConfig      `toml:"nvidia-container-runtime"`
	NVIDIAContainerRuntimeHookConfig RuntimeHookConfig  `toml:"nvidia-container-runtime-hook"`
}

// GetConfig sets up the config struct. Values are read from a toml file
// or set via the environment.
func GetConfig() (*Config, error) {
	if XDGConfigDir := os.Getenv(configOverride); len(XDGConfigDir) != 0 {
		configDir = XDGConfigDir
	}

	configFilePath := path.Join(configDir, configFilePath)

	tomlFile, err := os.Open(configFilePath)
	if err != nil {
		return getDefaultConfig(), nil
	}
	defer tomlFile.Close()

	cfg, err := loadConfigFrom(tomlFile)
	if err != nil {
		return nil, fmt.Errorf("failed to read config values: %v", err)
	}

	return cfg, nil
}

// loadRuntimeConfigFrom reads the config from the specified Reader
func loadConfigFrom(reader io.Reader) (*Config, error) {
	toml, err := toml.LoadReader(reader)
	if err != nil {
		return nil, err
	}

	return getConfigFrom(toml)
}

// getConfigFrom reads the nvidia container runtime config from the specified toml Tree.
func getConfigFrom(toml *toml.Tree) (*Config, error) {
	cfg := getDefaultConfig()

	if toml == nil {
		return cfg, nil
	}

	cfg.AcceptEnvvarUnprivileged = toml.GetDefault("accept-nvidia-visible-devices-envvar-when-unprivileged", cfg.AcceptEnvvarUnprivileged).(bool)

	cfg.NVIDIAContainerCLIConfig = *getContainerCLIConfigFrom(toml)
	cfg.NVIDIACTKConfig = *getCTKConfigFrom(toml)
	runtimeConfig, err := getRuntimeConfigFrom(toml)
	if err != nil {
		return nil, fmt.Errorf("failed to load nvidia-container-runtime config: %v", err)
	}
	cfg.NVIDIAContainerRuntimeConfig = *runtimeConfig

	runtimeHookConfig, err := getRuntimeHookConfigFrom(toml)
	if err != nil {
		return nil, fmt.Errorf("failed to load nvidia-container-runtime-hook config: %v", err)
	}
	cfg.NVIDIAContainerRuntimeHookConfig = *runtimeHookConfig

	return cfg, nil
}

// getDefaultConfig defines the default values for the config
func getDefaultConfig() *Config {
	c := Config{
		AcceptEnvvarUnprivileged:     true,
		NVIDIAContainerCLIConfig:     *getDefaultContainerCLIConfig(),
		NVIDIACTKConfig:              *getDefaultCTKConfig(),
		NVIDIAContainerRuntimeConfig: *GetDefaultRuntimeConfig(),
	}

	return &c
}

// ResolveNVIDIAContainerRuntimeHookPath resolves the path the nvidia-container-runtime-hook binary.
func ResolveNVIDIAContainerRuntimeHookPath(logger *logrus.Logger, nvidiaContainerRuntimeHookPath string) string {
	return resolveWithDefault(
		logger,
		"NVIDIA Container Runtime Hook",
		nvidiaContainerRuntimeHookPath,
		nvidiaContainerRuntimeHookDefaultPath,
	)
}

// resolveWithDefault resolves the path to the specified binary.
// If an absolute path is specified, it is used directly without searching for the binary.
// If the binary cannot be found in the path, the specified default is used instead.
func resolveWithDefault(logger *logrus.Logger, label string, path string, defaultPath string) string {
	if filepath.IsAbs(path) {
		logger.Debugf("Using specified %v path %v", label, path)
		return path
	}

	if path == "" {
		path = filepath.Base(defaultPath)
	}
	logger.Debugf("Locating %v as %v", label, path)
	lookup := lookup.NewExecutableLocator(logger, "")

	resolvedPath := defaultPath
	targets, err := lookup.Locate(path)
	if err != nil {
		logger.Warnf("Failed to locate %v: %v", path, err)
	} else {
		logger.Debugf("Found %v candidates: %v", path, targets)
		resolvedPath = targets[0]
	}
	logger.Debugf("Using %v path %v", label, path)

	return resolvedPath
}