Export pkg config/engine

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

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
+}