Use config package to handle all controller configurations

Description

Related Issue

Motivation and Context

How Has This Been Tested?

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

cmd/root.go

@@ -97,19 +97,6 @@ func initConfig() {
 		viper.AddConfigPath("/usr/local/etc/gosdn/")
 		viper.SetConfigType(configType)
 		viper.SetConfigName(configName)
-
-		// Viper will crash if you call 'WriteConfig()' and the file does
-		// not exists yet.
-		// Therefore we handle this case here.
-		// Inspired by //https://github.com/spf13/viper/issues/430#issuecomment-661945101
-		configPath := filepath.Join(configHome, configName+"."+configType)
-
-		if _, err := os.Stat(configPath); os.IsNotExist(err) {
-			err := ensureFileSystemStoreExists(configPath)
-			if err != nil {
-				panic(err)
-			}
-		}
 	}
 
 	viper.AutomaticEnv() // read in environment variables that match
@@ -117,6 +104,8 @@ func initConfig() {
 	// If a config file is found, read it in.
 	if err := viper.ReadInConfig(); err == nil {
 		log.Debug("Using config file:", viper.ConfigFileUsed())
+	} else {
+		ensureViperConfigFileExists()
 	}
 
 	viper.SetDefault("socket", ":55055")
@@ -148,3 +137,18 @@ func ensureFileSystemStoreExists(pathToStore string) error {
 
 	return nil
 }
+
+func ensureViperConfigFileExists() {
+	// Viper will crash if you call 'WriteConfig()' and the file does
+	// not exists yet.
+	// Therefore we handle this case here.
+	// Inspired by //https://github.com/spf13/viper/issues/430#issuecomment-661945101
+	configPath := filepath.Join(configHome, configName+"."+configType)
+
+	if _, err := os.Stat(configPath); os.IsNotExist(err) {
+		err := ensureFileSystemStoreExists(configPath)
+		if err != nil {
+			panic(err)
+		}
+	}
+}