Move docker config handling to internal package

In preparation for adding a command to the nvidia-ctk CLI to modify
the docker config, this change refactors load, update, and flush logic
from the toolkit container docker CLI to an internal package.

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

internal/config/docker/docker.go

@@ -0,0 +1,115 @@
+/**
+# 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 (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"os"
+
+	log "github.com/sirupsen/logrus"
+)
+
+// LoadConfig loads the docker config from disk
+func LoadConfig(configFilePath string) (map[string]interface{}, 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(map[string]interface{})
+
+	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
+}
+
+// UpdateConfig updates the docker config to include the nvidia runtimes
+func UpdateConfig(config map[string]interface{}, defaultRuntime string, newRuntimes map[string]interface{}) error {
+	if defaultRuntime != "" {
+		config["default-runtime"] = defaultRuntime
+	}
+
+	// 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
+	for name, rt := range newRuntimes {
+		runtimes[name] = rt
+	}
+
+	// Update the runtimes definition
+	if len(runtimes) > 0 {
+		config["runtimes"] = runtimes
+	}
+	return nil
+}
+
+// FlushConfig flushes the updated/reverted config out to disk
+func FlushConfig(cfg map[string]interface{}, configFilePath string) error {
+	log.Infof("Flushing docker config to %v", configFilePath)
+
+	output, err := json.MarshalIndent(cfg, "", "    ")
+	if err != nil {
+		return fmt.Errorf("unable to convert to JSON: %v", err)
+	}
+
+	switch len(output) {
+	case 0:
+		err := os.Remove(configFilePath)
+		if err != nil {
+			return fmt.Errorf("unable to remove empty file: %v", err)
+		}
+		log.Infof("Config empty, removing file")
+	default:
+		f, err := os.Create(configFilePath)
+		if err != nil {
+			return fmt.Errorf("unable to open %v for writing: %v", configFilePath, err)
+		}
+		defer f.Close()
+
+		_, err = f.WriteString(string(output))
+		if err != nil {
+			return fmt.Errorf("unable to write output: %v", err)
+		}
+	}
+
+	log.Infof("Successfully flushed config")
+
+	return nil
+}

internal/config/docker/docker_test.go

@@ -0,0 +1,228 @@
+/**
+# 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                     map[string]interface{}
+		defaultRuntime             string
+		runtimeName                string
+		expectedDefaultRuntimeName interface{}
+	}{
+		{
+			defaultRuntime:             "",
+			expectedDefaultRuntimeName: nil,
+		},
+		{
+			defaultRuntime:             "NAME",
+			expectedDefaultRuntimeName: "NAME",
+		},
+		{
+			config: map[string]interface{}{
+				"default-runtime": "ALREADY_SET",
+			},
+			defaultRuntime:             "",
+			expectedDefaultRuntimeName: "ALREADY_SET",
+		},
+		{
+			config: map[string]interface{}{
+				"default-runtime": "ALREADY_SET",
+			},
+			defaultRuntime:             "NAME",
+			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 := UpdateConfig(tc.config, tc.defaultRuntime, nil)
+			require.NoError(t, err)
+
+			defaultRuntimeName := tc.config["default-runtime"]
+			require.EqualValues(t, tc.expectedDefaultRuntimeName, defaultRuntimeName)
+		})
+	}
+}
+
+func TestUpdateConfigRuntimes(t *testing.T) {
+	testCases := []struct {
+		config         map[string]interface{}
+		runtimes       map[string]interface{}
+		expectedConfig map[string]interface{}
+	}{
+		{
+			config: 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{},
+				},
+			},
+			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]interface{}{
+				"runtime1": map[string]interface{}{
+					"path": "/test/runtime/dir/runtime1",
+					"args": []string{},
+				},
+				"runtime2": map[string]interface{}{
+					"path": "/test/runtime/dir/runtime2",
+					"args": []string{},
+				},
+			},
+			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]interface{}{
+				"runtime1": map[string]interface{}{
+					"path": "/test/runtime/dir/runtime1",
+					"args": []string{},
+				},
+			},
+			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]interface{}{
+				"runtime1": map[string]interface{}{
+					"path": "/test/runtime/dir/runtime1",
+					"args": []string{},
+				},
+			},
+			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) {
+			err := UpdateConfig(tc.config, "", tc.runtimes)
+			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))
+		})
+
+	}
+}

tools/container/docker/docker.go

@@ -17,16 +17,14 @@
 package main
 
 import (
-	"bytes"
-	"encoding/json"
 	"fmt"
-	"io/ioutil"
 	"net"
 	"os"
 	"path/filepath"
 	"syscall"
 	"time"
 
+	"github.com/NVIDIA/nvidia-container-toolkit/internal/config/docker"
 	log "github.com/sirupsen/logrus"
 	cli "github.com/urfave/cli/v2"
 )
@@ -247,52 +245,15 @@ func ParseArgs(c *cli.Context) (string, error) {
 
 // LoadConfig loads the docker config from disk
 func LoadConfig(config string) (map[string]interface{}, 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")
-	}
-
-	cfg := make(map[string]interface{})
-
-	if os.IsNotExist(err) {
-		log.Infof("Config file does not exist, creating new one")
-		return cfg, nil
-	}
-
-	readBytes, err := ioutil.ReadFile(config)
-	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
+	return docker.LoadConfig(config)
 }
 
 // UpdateConfig updates the docker config to include the nvidia runtimes
 func UpdateConfig(config map[string]interface{}, o *options) error {
 	defaultRuntime := o.getDefaultRuntime()
-	if defaultRuntime != "" {
-		config["default-runtime"] = defaultRuntime
-	}
+	runtimes := o.runtimes()
 
-	runtimes := make(map[string]interface{})
-	if _, exists := config["runtimes"]; exists {
-		runtimes = config["runtimes"].(map[string]interface{})
-	}
-
-	for name, rt := range o.runtimes() {
-		runtimes[name] = rt
-	}
-
-	config["runtimes"] = runtimes
-	return nil
+	return docker.UpdateConfig(config, defaultRuntime, runtimes)
 }
 
 //RevertConfig reverts the docker config to remove the nvidia runtime
@@ -320,36 +281,7 @@ func RevertConfig(config map[string]interface{}) error {
 
 // FlushConfig flushes the updated/reverted config out to disk
 func FlushConfig(cfg map[string]interface{}, config string) error {
-	log.Infof("Flushing config")
-
-	output, err := json.MarshalIndent(cfg, "", "    ")
-	if err != nil {
-		return fmt.Errorf("unable to convert to JSON: %v", err)
-	}
-
-	switch len(output) {
-	case 0:
-		err := os.Remove(config)
-		if err != nil {
-			return fmt.Errorf("unable to remove empty file: %v", err)
-		}
-		log.Infof("Config empty, removing file")
-	default:
-		f, err := os.Create(config)
-		if err != nil {
-			return fmt.Errorf("unable to open %v for writing: %v", config, err)
-		}
-		defer f.Close()
-
-		_, err = f.WriteString(string(output))
-		if err != nil {
-			return fmt.Errorf("unable to write output: %v", err)
-		}
-	}
-
-	log.Infof("Successfully flushed config")
-
-	return nil
+	return docker.FlushConfig(cfg, config)
 }
 
 // RestartDocker restarts docker depending on the value of restartModeFlag