Refactor loading of hook configs

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

cmd/nvidia-container-runtime-hook/hook_config.go

@@ -8,7 +8,6 @@ import (
 	"reflect"
 	"strings"
 
-	"github.com/BurntSushi/toml"
 	"github.com/NVIDIA/nvidia-container-toolkit/internal/config"
 	"github.com/NVIDIA/nvidia-container-toolkit/internal/config/image"
 )
@@ -18,10 +17,7 @@ const (
 	driverPath = "/run/nvidia/driver"
 )
 
-var defaultPaths = [...]string{
+var defaultPaths = [...]string{}
-	path.Join(driverPath, configPath),
-	configPath,
-}
 
 // HookConfig : options for the nvidia-container-runtime-hook.
 type HookConfig config.Config
@@ -35,34 +31,37 @@ func getDefaultHookConfig() (HookConfig, error) {
 	return *(*HookConfig)(defaultCfg), nil
 }
 
-func getHookConfig() (*HookConfig, error) {
+// loadConfig loads the required paths for the hook config.
-	var err error
+func loadConfig() (*config.Config, error) {
-	var config HookConfig
+	var configPaths []string
-
+	var required bool
-	if len(*configflag) > 0 {
+	if len(*configflag) != 0 {
-		config, err = getDefaultHookConfig()
+		configPaths = append(configPaths, *configflag)
-		if err != nil {
+		required = true
-			return nil, fmt.Errorf("couldn't get default configuration: %v", err)
-		}
-		_, err = toml.DecodeFile(*configflag, &config)
-		if err != nil {
-			return nil, fmt.Errorf("couldn't open configuration file: %v", err)
-		}
 	} else {
-		for _, p := range defaultPaths {
+		configPaths = append(configPaths, path.Join(driverPath, configPath), configPath)
-			config, err = getDefaultHookConfig()
-			if err != nil {
-				return nil, fmt.Errorf("couldn't get default configuration: %v", err)
-			}
-			_, err = toml.DecodeFile(p, &config)
-			if err == nil {
-				break
-			} else if !os.IsNotExist(err) {
-				return nil, fmt.Errorf("couldn't open default configuration file: %v", err)
-			}
-		}
 	}
 
+	for _, p := range configPaths {
+		cfg, err := config.Load(p)
+		if err == nil {
+			return cfg, nil
+		} else if os.IsNotExist(err) && !required {
+			continue
+		}
+		return nil, fmt.Errorf("couldn't open configuration file: %v", err)
+	}
+
+	return config.GetDefault()
+}
+
+func getHookConfig() (*HookConfig, error) {
+	cfg, err := loadConfig()
+	if err != nil {
+		return nil, fmt.Errorf("failed to load config: %v", err)
+	}
+	config := (*HookConfig)(cfg)
+
 	allSupportedDriverCapabilities := image.SupportedDriverCapabilities
 	if config.SupportedDriverCapabilities == "all" {
 		config.SupportedDriverCapabilities = allSupportedDriverCapabilities.String()
@@ -74,7 +73,7 @@ func getHookConfig() (*HookConfig, error) {
 		log.Panicf("Invalid value for config option '%v'; %v (supported: %v)\n", configName, config.SupportedDriverCapabilities, allSupportedDriverCapabilities.String())
 	}
 
-	return &config, nil
+	return config, nil
 }
 
 // getConfigOption returns the toml config option associated with the