Export pkg config/engine

Signed-off-by: Carlos Eduardo Arango Gutierrez <eduardoa@nvidia.com>

pkg/config/engine/api.go

@@ -0,0 +1,25 @@
+/**
+# Copyright (c) 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 engine
+
+// Interface defines the API for a runtime config updater.
+type Interface interface {
+	DefaultRuntime() string
+	AddRuntime(string, string, bool) error
+	RemoveRuntime(string) error
+	Save(string) (int64, error)
+}

pkg/config/engine/containerd/config_v1.go

@@ -0,0 +1,140 @@
+/**
+# Copyright (c) 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 containerd
+
+import (
+	"fmt"
+
+	"github.com/NVIDIA/nvidia-container-toolkit/pkg/config/engine"
+	"github.com/pelletier/go-toml"
+)
+
+// ConfigV1 represents a version 1 containerd config
+type ConfigV1 Config
+
+var _ engine.Interface = (*ConfigV1)(nil)
+
+// AddRuntime adds a runtime to the containerd config
+func (c *ConfigV1) AddRuntime(name string, path string, setAsDefault bool) error {
+	if c == nil || c.Tree == nil {
+		return fmt.Errorf("config is nil")
+	}
+
+	config := *c.Tree
+
+	config.Set("version", int64(1))
+
+	switch runc := config.GetPath([]string{"plugins", "cri", "containerd", "runtimes", "runc"}).(type) {
+	case *toml.Tree:
+		runc, _ = toml.Load(runc.String())
+		config.SetPath([]string{"plugins", "cri", "containerd", "runtimes", name}, runc)
+	}
+
+	if config.GetPath([]string{"plugins", "cri", "containerd", "runtimes", name}) == nil {
+		config.SetPath([]string{"plugins", "cri", "containerd", "runtimes", name, "runtime_type"}, c.RuntimeType)
+		config.SetPath([]string{"plugins", "cri", "containerd", "runtimes", name, "runtime_root"}, "")
+		config.SetPath([]string{"plugins", "cri", "containerd", "runtimes", name, "runtime_engine"}, "")
+		config.SetPath([]string{"plugins", "cri", "containerd", "runtimes", name, "privileged_without_host_devices"}, false)
+	}
+
+	if len(c.ContainerAnnotations) > 0 {
+		annotations, err := (*Config)(c).getRuntimeAnnotations([]string{"plugins", "cri", "containerd", "runtimes", name, "container_annotations"})
+		if err != nil {
+			return err
+		}
+		annotations = append(c.ContainerAnnotations, annotations...)
+		config.SetPath([]string{"plugins", "cri", "containerd", "runtimes", name, "container_annotations"}, annotations)
+	}
+
+	config.SetPath([]string{"plugins", "cri", "containerd", "runtimes", name, "options", "BinaryName"}, path)
+	config.SetPath([]string{"plugins", "cri", "containerd", "runtimes", name, "options", "Runtime"}, path)
+
+	if setAsDefault && c.UseDefaultRuntimeName {
+		config.SetPath([]string{"plugins", "cri", "containerd", "default_runtime_name"}, name)
+	} else if setAsDefault {
+		// Note: This is deprecated in containerd 1.4.0 and will be removed in 1.5.0
+		if config.GetPath([]string{"plugins", "cri", "containerd", "default_runtime"}) == nil {
+			config.SetPath([]string{"plugins", "cri", "containerd", "default_runtime", "runtime_type"}, c.RuntimeType)
+			config.SetPath([]string{"plugins", "cri", "containerd", "default_runtime", "runtime_root"}, "")
+			config.SetPath([]string{"plugins", "cri", "containerd", "default_runtime", "runtime_engine"}, "")
+			config.SetPath([]string{"plugins", "cri", "containerd", "default_runtime", "privileged_without_host_devices"}, false)
+		}
+		config.SetPath([]string{"plugins", "cri", "containerd", "default_runtime", "options", "BinaryName"}, path)
+		config.SetPath([]string{"plugins", "cri", "containerd", "default_runtime", "options", "Runtime"}, path)
+	}
+
+	*c.Tree = config
+	return nil
+}
+
+// DefaultRuntime returns the default runtime for the cri-o config
+func (c ConfigV1) DefaultRuntime() string {
+	if runtime, ok := c.GetPath([]string{"plugins", "cri", "containerd", "default_runtime_name"}).(string); ok {
+		return runtime
+	}
+	return ""
+}
+
+// RemoveRuntime removes a runtime from the docker config
+func (c *ConfigV1) RemoveRuntime(name string) error {
+	if c == nil || c.Tree == nil {
+		return nil
+	}
+
+	config := *c.Tree
+
+	// If the specified runtime was set as the default runtime we need to remove the default runtime too.
+	runtimePath, ok := config.GetPath([]string{"plugins", "cri", "containerd", "runtimes", name, "options", "BinaryName"}).(string)
+	if !ok || runtimePath == "" {
+		runtimePath, _ = config.GetPath([]string{"plugins", "cri", "containerd", "runtimes", name, "options", "Runtime"}).(string)
+	}
+	defaultRuntimePath, ok := config.GetPath([]string{"plugins", "cri", "containerd", "default_runtime", "options", "BinaryName"}).(string)
+	if !ok || defaultRuntimePath == "" {
+		defaultRuntimePath, _ = config.GetPath([]string{"plugins", "cri", "containerd", "default_runtime", "options", "Runtime"}).(string)
+	}
+	if runtimePath != "" && defaultRuntimePath != "" && runtimePath == defaultRuntimePath {
+		config.DeletePath([]string{"plugins", "cri", "containerd", "default_runtime"})
+	}
+
+	config.DeletePath([]string{"plugins", "cri", "containerd", "runtimes", name})
+	if runtime, ok := config.GetPath([]string{"plugins", "cri", "containerd", "default_runtime_name"}).(string); ok {
+		if runtime == name {
+			config.DeletePath([]string{"plugins", "cri", "containerd", "default_runtime_name"})
+		}
+	}
+
+	runtimeConfigPath := []string{"plugins", "cri", "containerd", "runtimes", name}
+	for i := 0; i < len(runtimeConfigPath); i++ {
+		if runtimes, ok := config.GetPath(runtimeConfigPath[:len(runtimeConfigPath)-i]).(*toml.Tree); ok {
+			if len(runtimes.Keys()) == 0 {
+				config.DeletePath(runtimeConfigPath[:len(runtimeConfigPath)-i])
+			}
+		}
+	}
+
+	if len(config.Keys()) == 1 && config.Keys()[0] == "version" {
+		config.Delete("version")
+	}
+
+	*c.Tree = config
+	return nil
+}
+
+// Save wrotes the config to a file
+func (c ConfigV1) Save(path string) (int64, error) {
+	return (Config)(c).Save(path)
+}

pkg/config/engine/containerd/config_v2.go

@@ -0,0 +1,166 @@
+/**
+# Copyright (c) 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 containerd
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/pelletier/go-toml"
+)
+
+// AddRuntime adds a runtime to the containerd config
+func (c *Config) AddRuntime(name string, path string, setAsDefault bool) error {
+	if c == nil || c.Tree == nil {
+		return fmt.Errorf("config is nil")
+	}
+	config := *c.Tree
+
+	config.Set("version", int64(2))
+
+	switch runc := config.GetPath([]string{"plugins", "io.containerd.grpc.v1.cri", "containerd", "runtimes", "runc"}).(type) {
+	case *toml.Tree:
+		runc, _ = toml.Load(runc.String())
+		config.SetPath([]string{"plugins", "io.containerd.grpc.v1.cri", "containerd", "runtimes", name}, runc)
+	}
+
+	if config.GetPath([]string{"plugins", "io.containerd.grpc.v1.cri", "containerd", "runtimes", name}) == nil {
+		config.SetPath([]string{"plugins", "io.containerd.grpc.v1.cri", "containerd", "runtimes", name, "runtime_type"}, c.RuntimeType)
+		config.SetPath([]string{"plugins", "io.containerd.grpc.v1.cri", "containerd", "runtimes", name, "runtime_root"}, "")
+		config.SetPath([]string{"plugins", "io.containerd.grpc.v1.cri", "containerd", "runtimes", name, "runtime_engine"}, "")
+		config.SetPath([]string{"plugins", "io.containerd.grpc.v1.cri", "containerd", "runtimes", name, "privileged_without_host_devices"}, false)
+	}
+
+	if len(c.ContainerAnnotations) > 0 {
+		annotations, err := c.getRuntimeAnnotations([]string{"plugins", "io.containerd.grpc.v1.cri", "containerd", "runtimes", name, "container_annotations"})
+		if err != nil {
+			return err
+		}
+		annotations = append(c.ContainerAnnotations, annotations...)
+		config.SetPath([]string{"plugins", "io.containerd.grpc.v1.cri", "containerd", "runtimes", name, "container_annotations"}, annotations)
+	}
+
+	config.SetPath([]string{"plugins", "io.containerd.grpc.v1.cri", "containerd", "runtimes", name, "options", "BinaryName"}, path)
+
+	if setAsDefault {
+		config.SetPath([]string{"plugins", "io.containerd.grpc.v1.cri", "containerd", "default_runtime_name"}, name)
+	}
+
+	*c.Tree = config
+	return nil
+}
+
+func (c *Config) getRuntimeAnnotations(path []string) ([]string, error) {
+	if c == nil || c.Tree == nil {
+		return nil, nil
+	}
+
+	config := *c.Tree
+	if !config.HasPath(path) {
+		return nil, nil
+	}
+	annotationsI, ok := config.GetPath(path).([]interface{})
+	if !ok {
+		return nil, fmt.Errorf("invalid annotations: %v", annotationsI)
+	}
+
+	var annotations []string
+	for _, annotation := range annotationsI {
+		a, ok := annotation.(string)
+		if !ok {
+			return nil, fmt.Errorf("invalid annotation: %v", annotation)
+		}
+		annotations = append(annotations, a)
+	}
+
+	return annotations, nil
+}
+
+// DefaultRuntime returns the default runtime for the cri-o config
+func (c Config) DefaultRuntime() string {
+	if runtime, ok := c.GetPath([]string{"plugins", "io.containerd.grpc.v1.cri", "containerd", "default_runtime_name"}).(string); ok {
+		return runtime
+	}
+	return ""
+}
+
+// RemoveRuntime removes a runtime from the docker config
+func (c *Config) RemoveRuntime(name string) error {
+	if c == nil || c.Tree == nil {
+		return nil
+	}
+
+	config := *c.Tree
+
+	config.DeletePath([]string{"plugins", "io.containerd.grpc.v1.cri", "containerd", "runtimes", name})
+	if runtime, ok := config.GetPath([]string{"plugins", "io.containerd.grpc.v1.cri", "containerd", "default_runtime_name"}).(string); ok {
+		if runtime == name {
+			config.DeletePath([]string{"plugins", "io.containerd.grpc.v1.cri", "containerd", "default_runtime_name"})
+		}
+	}
+
+	runtimePath := []string{"plugins", "io.containerd.grpc.v1.cri", "containerd", "runtimes", name}
+	for i := 0; i < len(runtimePath); i++ {
+		if runtimes, ok := config.GetPath(runtimePath[:len(runtimePath)-i]).(*toml.Tree); ok {
+			if len(runtimes.Keys()) == 0 {
+				config.DeletePath(runtimePath[:len(runtimePath)-i])
+			}
+		}
+	}
+
+	if len(config.Keys()) == 1 && config.Keys()[0] == "version" {
+		config.Delete("version")
+	}
+
+	*c.Tree = config
+	return nil
+}
+
+// Save writes the config to the specified path
+func (c Config) Save(path string) (int64, error) {
+	config := c.Tree
+	output, err := config.ToTomlString()
+	if err != nil {
+		return 0, fmt.Errorf("unable to convert to TOML: %v", err)
+	}
+
+	if path == "" {
+		os.Stdout.WriteString(fmt.Sprintf("%s\n", output))
+		return int64(len(output)), nil
+	}
+
+	if len(output) == 0 {
+		err := os.Remove(path)
+		if err != nil {
+			return 0, fmt.Errorf("unable to remove empty file: %v", err)
+		}
+		return 0, nil
+	}
+
+	f, err := os.Create(path)
+	if err != nil {
+		return 0, fmt.Errorf("unable to open '%v' for writing: %v", path, err)
+	}
+	defer f.Close()
+
+	n, err := f.WriteString(output)
+	if err != nil {
+		return 0, fmt.Errorf("unable to write output: %v", err)
+	}
+
+	return int64(n), err
+}

pkg/config/engine/containerd/containerd.go

@@ -0,0 +1,40 @@
+/**
+# 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 containerd
+
+import (
+	"github.com/NVIDIA/nvidia-container-toolkit/pkg/config/engine"
+	"github.com/pelletier/go-toml"
+)
+
+// Config represents the containerd config
+type Config struct {
+	*toml.Tree
+	RuntimeType           string
+	UseDefaultRuntimeName bool
+	ContainerAnnotations  []string
+}
+
+// New creates a containerd config with the specified options
+func New(opts ...Option) (engine.Interface, error) {
+	b := &builder{}
+	for _, opt := range opts {
+		opt(b)
+	}
+
+	return b.build()
+}

pkg/config/engine/containerd/option.go

@@ -0,0 +1,149 @@
+/**
+# Copyright (c) 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 containerd
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/NVIDIA/nvidia-container-toolkit/pkg/config/engine"
+	"github.com/pelletier/go-toml"
+	log "github.com/sirupsen/logrus"
+)
+
+const (
+	defaultRuntimeType = "io.containerd.runc.v2"
+)
+
+type builder struct {
+	path                 string
+	runtimeType          string
+	useLegacyConfig      bool
+	containerAnnotations []string
+}
+
+// Option defines a function that can be used to configure the config builder
+type Option func(*builder)
+
+// WithPath sets the path for the config builder
+func WithPath(path string) Option {
+	return func(b *builder) {
+		b.path = path
+	}
+}
+
+// WithRuntimeType sets the runtime type for the config builder
+func WithRuntimeType(runtimeType string) Option {
+	return func(b *builder) {
+		b.runtimeType = runtimeType
+	}
+}
+
+// WithUseLegacyConfig sets the useLegacyConfig flag for the config builder
+func WithUseLegacyConfig(useLegacyConfig bool) Option {
+	return func(b *builder) {
+		b.useLegacyConfig = useLegacyConfig
+	}
+}
+
+// WithContainerAnnotations sets the container annotations for the config builder
+func WithContainerAnnotations(containerAnnotations ...string) Option {
+	return func(b *builder) {
+		b.containerAnnotations = containerAnnotations
+	}
+}
+
+func (b *builder) build() (engine.Interface, error) {
+	if b.path == "" {
+		return nil, fmt.Errorf("config path is empty")
+	}
+
+	if b.runtimeType == "" {
+		b.runtimeType = defaultRuntimeType
+	}
+
+	config, err := loadConfig(b.path)
+	if err != nil {
+		return nil, fmt.Errorf("failed to load config: %v", err)
+	}
+	config.RuntimeType = b.runtimeType
+	config.UseDefaultRuntimeName = !b.useLegacyConfig
+	config.ContainerAnnotations = b.containerAnnotations
+
+	version, err := config.parseVersion(b.useLegacyConfig)
+	if err != nil {
+		return nil, fmt.Errorf("failed to parse config version: %v", err)
+	}
+	switch version {
+	case 1:
+		return (*ConfigV1)(config), nil
+	case 2:
+		return config, nil
+	}
+
+	return nil, fmt.Errorf("unsupported config version: %v", version)
+}
+
+// loadConfig loads the containerd config from disk
+func loadConfig(config string) (*Config, error) {
+	log.Infof("Loading config: %v", config)
+
+	info, err := os.Stat(config)
+	if os.IsExist(err) && info.IsDir() {
+		return nil, fmt.Errorf("config file is a directory")
+	}
+
+	configFile := config
+	if os.IsNotExist(err) {
+		configFile = "/dev/null"
+		log.Infof("Config file does not exist, creating new one")
+	}
+
+	tomlConfig, err := toml.LoadFile(configFile)
+	if err != nil {
+		return nil, err
+	}
+
+	log.Infof("Successfully loaded config")
+
+	cfg := Config{
+		Tree: tomlConfig,
+	}
+	return &cfg, nil
+}
+
+// parseVersion returns the version of the config
+func (c *Config) parseVersion(useLegacyConfig bool) (int, error) {
+	defaultVersion := 2
+	if useLegacyConfig {
+		defaultVersion = 1
+	}
+
+	switch v := c.Get("version").(type) {
+	case nil:
+		switch len(c.Keys()) {
+		case 0: // No config exists, or the config file is empty, use version inferred from containerd
+			return defaultVersion, nil
+		default: // A config file exists, has content, and no version is set
+			return 1, nil
+		}
+	case int64:
+		return int(v), nil
+	default:
+		return -1, fmt.Errorf("unsupported type for version field: %v", v)
+	}
+}

pkg/config/engine/crio/crio.go

@@ -0,0 +1,136 @@
+/**
+# 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 crio
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/NVIDIA/nvidia-container-toolkit/pkg/config/engine"
+	"github.com/pelletier/go-toml"
+)
+
+// Config represents the cri-o config
+type Config toml.Tree
+
+// New creates a cri-o config with the specified options
+func New(opts ...Option) (engine.Interface, error) {
+	b := &builder{}
+	for _, opt := range opts {
+		opt(b)
+	}
+
+	return b.build()
+}
+
+// AddRuntime adds a new runtime to the crio config
+func (c *Config) AddRuntime(name string, path string, setAsDefault bool) error {
+	if c == nil {
+		return fmt.Errorf("config is nil")
+	}
+
+	config := (toml.Tree)(*c)
+
+	switch runc := config.Get("crio.runtime.runtimes.runc").(type) {
+	case *toml.Tree:
+		runc, _ = toml.Load(runc.String())
+		config.SetPath([]string{"crio", "runtime", "runtimes", name}, runc)
+	}
+
+	config.SetPath([]string{"crio", "runtime", "runtimes", name, "runtime_path"}, path)
+	config.SetPath([]string{"crio", "runtime", "runtimes", name, "runtime_type"}, "oci")
+
+	if setAsDefault {
+		config.SetPath([]string{"crio", "runtime", "default_runtime"}, name)
+	}
+
+	*c = (Config)(config)
+	return nil
+}
+
+// DefaultRuntime returns the default runtime for the cri-o config
+func (c Config) DefaultRuntime() string {
+	config := (toml.Tree)(c)
+	if runtime, ok := config.GetPath([]string{"crio", "runtime", "default_runtime"}).(string); ok {
+		return runtime
+	}
+	return ""
+}
+
+// RemoveRuntime removes a runtime from the cri-o config
+func (c *Config) RemoveRuntime(name string) error {
+	if c == nil {
+		return nil
+	}
+
+	config := (toml.Tree)(*c)
+	if runtime, ok := config.GetPath([]string{"crio", "runtime", "default_runtime"}).(string); ok {
+		if runtime == name {
+			config.DeletePath([]string{"crio", "runtime", "default_runtime"})
+		}
+	}
+
+	runtimeClassPath := []string{"crio", "runtime", "runtimes", name}
+	config.DeletePath(runtimeClassPath)
+	for i := 0; i < len(runtimeClassPath); i++ {
+		remainingPath := runtimeClassPath[:len(runtimeClassPath)-i]
+		if entry, ok := config.GetPath(remainingPath).(*toml.Tree); ok {
+			if len(entry.Keys()) != 0 {
+				break
+			}
+			config.DeletePath(remainingPath)
+		}
+	}
+
+	*c = (Config)(config)
+	return nil
+}
+
+// Save writes the config to the specified path
+func (c Config) Save(path string) (int64, error) {
+	config := (toml.Tree)(c)
+	output, err := config.ToTomlString()
+	if err != nil {
+		return 0, fmt.Errorf("unable to convert to TOML: %v", err)
+	}
+
+	if path == "" {
+		os.Stdout.WriteString(fmt.Sprintf("%s\n", output))
+		return int64(len(output)), nil
+	}
+
+	if len(output) == 0 {
+		err := os.Remove(path)
+		if err != nil {
+			return 0, fmt.Errorf("unable to remove empty file: %v", err)
+		}
+		return 0, nil
+	}
+
+	f, err := os.Create(path)
+	if err != nil {
+		return 0, fmt.Errorf("unable to open '%v' for writing: %v", path, err)
+	}
+	defer f.Close()
+
+	n, err := f.WriteString(output)
+	if err != nil {
+		return 0, fmt.Errorf("unable to write output: %v", err)
+	}
+
+	return int64(n), err
+}

pkg/config/engine/crio/option.go

@@ -0,0 +1,73 @@
+/**
+# Copyright (c) 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 crio
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/pelletier/go-toml"
+	log "github.com/sirupsen/logrus"
+)
+
+type builder struct {
+	path string
+}
+
+// Option defines a function that can be used to configure the config builder
+type Option func(*builder)
+
+// WithPath sets the path for the config builder
+func WithPath(path string) Option {
+	return func(b *builder) {
+		b.path = path
+	}
+}
+
+func (b *builder) build() (*Config, error) {
+	if b.path == "" {
+		empty := toml.Tree{}
+		return (*Config)(&empty), nil
+	}
+
+	return loadConfig(b.path)
+}
+
+// loadConfig loads the cri-o config from disk
+func loadConfig(config string) (*Config, error) {
+	log.Infof("Loading config: %v", config)
+
+	info, err := os.Stat(config)
+	if os.IsExist(err) && info.IsDir() {
+		return nil, fmt.Errorf("config file is a directory")
+	}
+
+	configFile := config
+	if os.IsNotExist(err) {
+		configFile = "/dev/null"
+		log.Infof("Config file does not exist, creating new one")
+	}
+
+	cfg, err := toml.LoadFile(configFile)
+	if err != nil {
+		return nil, err
+	}
+
+	log.Infof("Successfully loaded config")
+
+	return (*Config)(cfg), nil
+}

pkg/config/engine/docker/docker.go

@@ -0,0 +1,145 @@
+/**
+# Copyright (c) 2021-2022, 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 docker
+
+import (
+	"encoding/json"
+	"fmt"
+	"os"
+
+	"github.com/NVIDIA/nvidia-container-toolkit/pkg/config/engine"
+)
+
+const (
+	defaultDockerRuntime = "runc"
+)
+
+// Config defines a docker config file.
+// TODO: This should not be public, but we need to access it from the tests in tools/container/docker
+type Config map[string]interface{}
+
+// New creates a docker config with the specified options
+func New(opts ...Option) (engine.Interface, error) {
+	b := &builder{}
+	for _, opt := range opts {
+		opt(b)
+	}
+
+	return b.build()
+}
+
+// AddRuntime adds a new runtime to the docker config
+func (c *Config) AddRuntime(name string, path string, setAsDefault bool) error {
+	if c == nil {
+		return fmt.Errorf("config is nil")
+	}
+
+	config := *c
+
+	// Read the existing runtimes
+	runtimes := make(map[string]interface{})
+	if _, exists := config["runtimes"]; exists {
+		runtimes = config["runtimes"].(map[string]interface{})
+	}
+
+	// Add / update the runtime definitions
+	runtimes[name] = map[string]interface{}{
+		"path": path,
+		"args": []string{},
+	}
+
+	config["runtimes"] = runtimes
+
+	if setAsDefault {
+		config["default-runtime"] = name
+	}
+
+	*c = config
+	return nil
+}
+
+// DefaultRuntime returns the default runtime for the docker config
+func (c Config) DefaultRuntime() string {
+	r, ok := c["default-runtime"].(string)
+	if !ok {
+		return ""
+	}
+	return r
+}
+
+// RemoveRuntime removes a runtime from the docker config
+func (c *Config) RemoveRuntime(name string) error {
+	if c == nil {
+		return nil
+	}
+	config := *c
+
+	if _, exists := config["default-runtime"]; exists {
+		defaultRuntime := config["default-runtime"].(string)
+		if defaultRuntime == name {
+			config["default-runtime"] = defaultDockerRuntime
+		}
+	}
+
+	if _, exists := config["runtimes"]; exists {
+		runtimes := config["runtimes"].(map[string]interface{})
+
+		delete(runtimes, name)
+
+		if len(runtimes) == 0 {
+			delete(config, "runtimes")
+		}
+	}
+
+	*c = config
+
+	return nil
+}
+
+// Save writes the config to the specified path
+func (c Config) Save(path string) (int64, error) {
+	output, err := json.MarshalIndent(c, "", "    ")
+	if err != nil {
+		return 0, fmt.Errorf("unable to convert to JSON: %v", err)
+	}
+
+	if path == "" {
+		os.Stdout.WriteString(fmt.Sprintf("%s\n", output))
+		return int64(len(output)), nil
+	}
+
+	if len(output) == 0 {
+		err := os.Remove(path)
+		if err != nil {
+			return 0, fmt.Errorf("unable to remove empty file: %v", err)
+		}
+		return 0, nil
+	}
+
+	f, err := os.Create(path)
+	if err != nil {
+		return 0, fmt.Errorf("unable to open %v for writing: %v", path, err)
+	}
+	defer f.Close()
+
+	n, err := f.WriteString(string(output))
+	if err != nil {
+		return 0, fmt.Errorf("unable to write output: %v", err)
+	}
+
+	return int64(n), nil
+}

pkg/config/engine/docker/docker_test.go

@@ -0,0 +1,215 @@
+/**
+# Copyright (c) 2021-2022, 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 docker
+
+import (
+	"encoding/json"
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestUpdateConfigDefaultRuntime(t *testing.T) {
+	testCases := []struct {
+		config                     Config
+		runtimeName                string
+		setAsDefault               bool
+		expectedDefaultRuntimeName interface{}
+	}{
+		{
+			setAsDefault:               false,
+			expectedDefaultRuntimeName: nil,
+		},
+		{
+			runtimeName:                "NAME",
+			setAsDefault:               true,
+			expectedDefaultRuntimeName: "NAME",
+		},
+		{
+			config: map[string]interface{}{
+				"default-runtime": "ALREADY_SET",
+			},
+			runtimeName:                "NAME",
+			setAsDefault:               false,
+			expectedDefaultRuntimeName: "ALREADY_SET",
+		},
+		{
+			config: map[string]interface{}{
+				"default-runtime": "ALREADY_SET",
+			},
+			runtimeName:                "NAME",
+			setAsDefault:               true,
+			expectedDefaultRuntimeName: "NAME",
+		},
+	}
+
+	for i, tc := range testCases {
+		t.Run(fmt.Sprintf("test case %d", i), func(t *testing.T) {
+			if tc.config == nil {
+				tc.config = make(map[string]interface{})
+			}
+			err := tc.config.AddRuntime(tc.runtimeName, "", tc.setAsDefault)
+			require.NoError(t, err)
+
+			defaultRuntimeName := tc.config["default-runtime"]
+			require.EqualValues(t, tc.expectedDefaultRuntimeName, defaultRuntimeName)
+		})
+	}
+}
+
+func TestUpdateConfigRuntimes(t *testing.T) {
+	testCases := []struct {
+		config         Config
+		runtimes       map[string]string
+		expectedConfig map[string]interface{}
+	}{
+		{
+			config: map[string]interface{}{},
+			runtimes: map[string]string{
+				"runtime1": "/test/runtime/dir/runtime1",
+				"runtime2": "/test/runtime/dir/runtime2",
+			},
+			expectedConfig: map[string]interface{}{
+				"runtimes": map[string]interface{}{
+					"runtime1": map[string]interface{}{
+						"path": "/test/runtime/dir/runtime1",
+						"args": []string{},
+					},
+					"runtime2": map[string]interface{}{
+						"path": "/test/runtime/dir/runtime2",
+						"args": []string{},
+					},
+				},
+			},
+		},
+		{
+			config: map[string]interface{}{
+				"runtimes": map[string]interface{}{
+					"runtime1": map[string]interface{}{
+						"path": "runtime1",
+						"args": []string{},
+					},
+				},
+			},
+			runtimes: map[string]string{
+				"runtime1": "/test/runtime/dir/runtime1",
+				"runtime2": "/test/runtime/dir/runtime2",
+			},
+			expectedConfig: map[string]interface{}{
+				"runtimes": map[string]interface{}{
+					"runtime1": map[string]interface{}{
+						"path": "/test/runtime/dir/runtime1",
+						"args": []string{},
+					},
+					"runtime2": map[string]interface{}{
+						"path": "/test/runtime/dir/runtime2",
+						"args": []string{},
+					},
+				},
+			},
+		},
+		{
+			config: map[string]interface{}{
+				"runtimes": map[string]interface{}{
+					"not-nvidia": map[string]interface{}{
+						"path": "some-other-path",
+						"args": []string{},
+					},
+				},
+			},
+			runtimes: map[string]string{
+				"runtime1": "/test/runtime/dir/runtime1",
+			},
+			expectedConfig: map[string]interface{}{
+				"runtimes": map[string]interface{}{
+					"not-nvidia": map[string]interface{}{
+						"path": "some-other-path",
+						"args": []string{},
+					},
+					"runtime1": map[string]interface{}{
+						"path": "/test/runtime/dir/runtime1",
+						"args": []string{},
+					},
+				},
+			},
+		},
+		{
+			config: map[string]interface{}{
+				"exec-opts":  []string{"native.cgroupdriver=systemd"},
+				"log-driver": "json-file",
+				"log-opts": map[string]string{
+					"max-size": "100m",
+				},
+				"storage-driver": "overlay2",
+			},
+			runtimes: map[string]string{
+				"runtime1": "/test/runtime/dir/runtime1",
+			},
+			expectedConfig: map[string]interface{}{
+				"exec-opts":  []string{"native.cgroupdriver=systemd"},
+				"log-driver": "json-file",
+				"log-opts": map[string]string{
+					"max-size": "100m",
+				},
+				"storage-driver": "overlay2",
+				"runtimes": map[string]interface{}{
+					"runtime1": map[string]interface{}{
+						"path": "/test/runtime/dir/runtime1",
+						"args": []string{},
+					},
+				},
+			},
+		},
+		{
+			config: map[string]interface{}{
+				"exec-opts":  []string{"native.cgroupdriver=systemd"},
+				"log-driver": "json-file",
+				"log-opts": map[string]string{
+					"max-size": "100m",
+				},
+				"storage-driver": "overlay2",
+			},
+			expectedConfig: map[string]interface{}{
+				"exec-opts":  []string{"native.cgroupdriver=systemd"},
+				"log-driver": "json-file",
+				"log-opts": map[string]string{
+					"max-size": "100m",
+				},
+				"storage-driver": "overlay2",
+			},
+		},
+	}
+
+	for i, tc := range testCases {
+		t.Run(fmt.Sprintf("test case %d", i), func(t *testing.T) {
+			for runtimeName, runtimePath := range tc.runtimes {
+				err := tc.config.AddRuntime(runtimeName, runtimePath, false)
+				require.NoError(t, err)
+			}
+
+			configContent, err := json.MarshalIndent(tc.config, "", "    ")
+			require.NoError(t, err)
+
+			expectedContent, err := json.MarshalIndent(tc.expectedConfig, "", "    ")
+			require.NoError(t, err)
+
+			require.EqualValues(t, string(expectedContent), string(configContent))
+		})
+
+	}
+}

pkg/config/engine/docker/option.go

@@ -0,0 +1,80 @@
+/**
+# Copyright (c) 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 docker
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"os"
+
+	log "github.com/sirupsen/logrus"
+)
+
+type builder struct {
+	path string
+}
+
+// Option defines a function that can be used to configure the config builder
+type Option func(*builder)
+
+// WithPath sets the path for the config builder
+func WithPath(path string) Option {
+	return func(b *builder) {
+		b.path = path
+	}
+}
+
+func (b *builder) build() (*Config, error) {
+	if b.path == "" {
+		empty := make(Config)
+		return &empty, nil
+	}
+
+	return loadConfig(b.path)
+}
+
+// loadConfig loads the docker config from disk
+func loadConfig(configFilePath string) (*Config, error) {
+	log.Infof("Loading docker config from %v", configFilePath)
+
+	info, err := os.Stat(configFilePath)
+	if os.IsExist(err) && info.IsDir() {
+		return nil, fmt.Errorf("config file is a directory")
+	}
+
+	cfg := make(Config)
+
+	if os.IsNotExist(err) {
+		log.Infof("Config file does not exist, creating new one")
+		return &cfg, nil
+	}
+
+	readBytes, err := ioutil.ReadFile(configFilePath)
+	if err != nil {
+		return nil, fmt.Errorf("unable to read config: %v", err)
+	}
+
+	reader := bytes.NewReader(readBytes)
+	if err := json.NewDecoder(reader).Decode(&cfg); err != nil {
+		return nil, err
+	}
+
+	log.Infof("Successfully loaded config")
+	return &cfg, nil
+}