Add engine.Config to encapsulate writing

This change adds an engine.Config type to encapsulate the writing
of config files for container engines.

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

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

@@ -190,12 +190,14 @@ func (m command) configureWrapper(c *cli.Context, config *config) error {
 		return fmt.Errorf("unable to flush config: %v", err)
 	}
 
-	if n == 0 {
+	if outputPath != "" {
-		m.logger.Infof("Removed empty config from %v", outputPath)
+		if n == 0 {
-	} else {
+			m.logger.Infof("Removed empty config from %v", outputPath)
-		m.logger.Infof("Wrote updated config to %v", outputPath)
+		} else {
+			m.logger.Infof("Wrote updated config to %v", outputPath)
+		}
+		m.logger.Infof("It is recommended that %v daemon be restarted.", config.runtime)
 	}
-	m.logger.Infof("It is recommended that %v daemon be restarted.", config.runtime)
 
 	return nil
 }

pkg/config/engine/config.go

@@ -0,0 +1,53 @@
+/**
+# 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
+
+import (
+	"fmt"
+	"os"
+)
+
+// Config represents a runtime config
+type Config string
+
+// Write writes the specified contents to a config file.
+func (c Config) Write(output []byte) (int, error) {
+	path := string(c)
+	if path == "" {
+		n, err := os.Stdout.Write(output)
+		if err == nil {
+			os.Stdout.WriteString("\n")
+		}
+		return n, err
+	}
+
+	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()
+
+	return f.Write(output)
+}

pkg/config/engine/containerd/config_v2.go

@@ -18,8 +18,8 @@ package containerd
 
 import (
 	"fmt"
-	"os"
 
+	"github.com/NVIDIA/nvidia-container-toolkit/pkg/config/engine"
 	"github.com/pelletier/go-toml"
 )
 
@@ -133,34 +133,11 @@ func (c *Config) RemoveRuntime(name string) error {
 // Save writes the config to the specified path
 func (c Config) Save(path string) (int64, error) {
 	config := c.Tree
-	output, err := config.ToTomlString()
+	output, err := config.Marshal()
 	if err != nil {
 		return 0, fmt.Errorf("unable to convert to TOML: %v", err)
 	}
 
-	if path == "" {
+	n, err := engine.Config(path).Write(output)
-		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/option.go

@@ -108,26 +108,23 @@ func (b *builder) build() (engine.Interface, error) {
 
 // loadConfig loads the containerd config from disk
 func (b *builder) loadConfig(config string) (*Config, error) {
-	b.logger.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"
+		b.logger.Infof("Config file does not exist; using empty config")
-		b.logger.Infof("Config file does not exist, creating new one")
+		config = "/dev/null"
+	} else {
+		b.logger.Infof("Loading config from %v", config)
 	}
 
-	tomlConfig, err := toml.LoadFile(configFile)
+	tomlConfig, err := toml.LoadFile(config)
 	if err != nil {
 		return nil, err
 	}
 
-	b.logger.Infof("Successfully loaded config")
-
 	cfg := Config{
 		Tree: tomlConfig,
 	}

pkg/config/engine/crio/crio.go

@@ -18,7 +18,6 @@ package crio
 
 import (
 	"fmt"
-	"os"
 
 	"github.com/NVIDIA/nvidia-container-toolkit/pkg/config/engine"
 	"github.com/pelletier/go-toml"
@@ -103,34 +102,11 @@ func (c *Config) RemoveRuntime(name string) error {
 // Save writes the config to the specified path
 func (c Config) Save(path string) (int64, error) {
 	config := (toml.Tree)(c)
-	output, err := config.ToTomlString()
+	output, err := config.Marshal()
 	if err != nil {
 		return 0, fmt.Errorf("unable to convert to TOML: %v", err)
 	}
 
-	if path == "" {
+	n, err := engine.Config(path).Write(output)
-		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

@@ -67,13 +67,14 @@ func (b *builder) loadConfig(config string) (*Config, error) {
 		return nil, fmt.Errorf("config file is a directory")
 	}
 
-	configFile := config
 	if os.IsNotExist(err) {
-		configFile = "/dev/null"
+		b.logger.Infof("Config file does not exist; using empty config")
-		b.logger.Infof("Config file does not exist, creating new one")
+		config = "/dev/null"
+	} else {
+		b.logger.Infof("Loading config from %v", config)
 	}
 
-	cfg, err := toml.LoadFile(configFile)
+	cfg, err := toml.LoadFile(config)
 	if err != nil {
 		return nil, err
 	}

pkg/config/engine/docker/docker.go

@@ -19,7 +19,6 @@ package docker
 import (
 	"encoding/json"
 	"fmt"
-	"os"
 
 	"github.com/NVIDIA/nvidia-container-toolkit/internal/logger"
 	"github.com/NVIDIA/nvidia-container-toolkit/pkg/config/engine"
@@ -122,29 +121,6 @@ func (c Config) Save(path string) (int64, error) {
 		return 0, fmt.Errorf("unable to convert to JSON: %v", err)
 	}
 
-	if path == "" {
+	n, err := engine.Config(path).Write(output)
-		os.Stdout.WriteString(fmt.Sprintf("%s\n", output))
+	return int64(n), err
-		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/option.go

@@ -58,10 +58,8 @@ func (b *builder) build() (*Config, error) {
 }
 
 // loadConfig loads the docker config from disk
-func (b *builder) loadConfig(configFilePath string) (*Config, error) {
+func (b *builder) loadConfig(config string) (*Config, error) {
-	b.logger.Infof("Loading docker config from %v", configFilePath)
+	info, err := os.Stat(config)
-
-	info, err := os.Stat(configFilePath)
 	if os.IsExist(err) && info.IsDir() {
 		return nil, fmt.Errorf("config file is a directory")
 	}
@@ -69,11 +67,12 @@ func (b *builder) loadConfig(configFilePath string) (*Config, error) {
 	cfg := make(Config)
 
 	if os.IsNotExist(err) {
-		b.logger.Infof("Config file does not exist, creating new one")
+		b.logger.Infof("Config file does not exist; using empty config")
 		return &cfg, nil
 	}
 
-	readBytes, err := ioutil.ReadFile(configFilePath)
+	b.logger.Infof("Loading config from %v", config)
+	readBytes, err := ioutil.ReadFile(config)
 	if err != nil {
 		return nil, fmt.Errorf("unable to read config: %v", err)
 	}
@@ -82,7 +81,5 @@ func (b *builder) loadConfig(configFilePath string) (*Config, error) {
 	if err := json.NewDecoder(reader).Decode(&cfg); err != nil {
 		return nil, err
 	}
-
-	b.logger.Infof("Successfully loaded config")
 	return &cfg, nil
 }