Add strict mode.

viper.go

@@ -483,7 +483,7 @@ func (v *Viper) WatchConfig() {
 						(event.Has(fsnotify.Write) || event.Has(fsnotify.Create))) ||
 						(currentConfigFile != "" && currentConfigFile != realConfigFile) {
 						realConfigFile = currentConfigFile
-						err := v.ReadInConfig()
+						err := v.ReadInConfig(false)
 						if err != nil {
 							log.Printf("error reading config file: %v\n", err)
 						}
@@ -512,8 +512,10 @@ func (v *Viper) WatchConfig() {
 	initWG.Wait() // make sure that the go routine above fully ended before returning
 }
 
-// updateRegisteredConfig validate the registered config items in the new config, notify user with the hook functions.
-func (v *Viper) updateRegisteredConfig(newConfig map[string]interface{}) (result map[string]interface{}) {
+// updateRegisteredConfig validate the registered config items in the new config,
+// notify user with the hook functions.
+// Only when strict is true, err can be returned, only the last error will be returned.
+func (v *Viper) updateRegisteredConfig(newConfig map[string]interface{}, strict bool) (result map[string]interface{}, err error) {
 	result = make(map[string]interface{})
 
 	for key, config := range v.registered {
@@ -522,6 +524,7 @@ func (v *Viper) updateRegisteredConfig(newConfig map[string]interface{}) (result
 		// Check exist
 		if newValue == nil && !config.CanBeNil {
 			newConfig[key] = oldValue
+			err = errors.New(fmt.Sprintf("%s is nil or not found", key))
 			if config.OnUpdateFailed != nil {
 				config.OnUpdateFailed(&Event{
 					name:   v.name,
@@ -540,6 +543,7 @@ func (v *Viper) updateRegisteredConfig(newConfig map[string]interface{}) (result
 			if err != nil {
 				newConfig[key] = oldValue
 				if config.OnUpdateFailed != nil {
+					err = errors.New(fmt.Sprintf("%s is with a invalid type", key))
 					config.OnUpdateFailed(&Event{
 						name:   v.name,
 						old:    oldValue,
@@ -557,6 +561,7 @@ func (v *Viper) updateRegisteredConfig(newConfig map[string]interface{}) (result
 		if config.Validator != nil && !config.Validator(config.Schema) {
 			newConfig[key] = oldValue
 			if config.OnUpdateFailed != nil {
+				err = errors.New(fmt.Sprintf("%s validation failed", key))
 				config.OnUpdateFailed(&Event{
 					name:   v.name,
 					old:    oldValue,
@@ -577,7 +582,11 @@ func (v *Viper) updateRegisteredConfig(newConfig map[string]interface{}) (result
 			})
 		}
 	}
-	return result
+
+	if strict {
+		return result, err
+	}
+	return result, nil
 }
 
 // SetConfigFile explicitly defines the path, name and extension of the config file.
@@ -1633,9 +1642,13 @@ func (v *Viper) Set(key string, value interface{}) {
 
 // ReadInConfig will discover and load the configuration file from disk
 // and key/value stores, searching in one of the defined paths.
-func ReadInConfig() error { return v.ReadInConfig() }
+func ReadInConfig() error { return v.ReadInConfig(false) }
+
+// ReadInConfigStrict register the configs with strict manner: any validation
+// error  will result in failure.
+func ReadInConfigStrict() error { return v.ReadInConfig(true) }
 
-func (v *Viper) ReadInConfig() error {
+func (v *Viper) ReadInConfig(strict bool) error {
 	v.logger.Info("attempting to read in config file")
 	filename, err := v.getConfigFile()
 	if err != nil {
@@ -1657,7 +1670,10 @@ func (v *Viper) ReadInConfig() error {
 	if err != nil {
 		return err
 	}
-	config = v.updateRegisteredConfig(config)
+	config, err = v.updateRegisteredConfig(config, strict)
+	if strict && err != nil {
+		return err
+	}
 
 	v.config = config
 	return nil
@@ -2014,7 +2030,7 @@ func (v *Viper) getRemoteConfig(provider RemoteProvider) (map[string]interface{}
 	}
 	kvStore := make(map[string]interface{})
 	err = v.unmarshalReader(reader, kvStore)
-	v.kvstore = v.updateRegisteredConfig(kvStore)
+	v.kvstore, _ = v.updateRegisteredConfig(kvStore, false)
 	return v.kvstore, err
 }
 
@@ -2033,7 +2049,7 @@ func (v *Viper) watchKeyValueConfigOnChannel() error {
 				reader := bytes.NewReader(b.Value)
 				kvStore := make(map[string]interface{})
 				v.unmarshalReader(reader, kvStore)
-				v.kvstore = v.updateRegisteredConfig(kvStore)
+				v.kvstore, _ = v.updateRegisteredConfig(kvStore, false)
 			}
 		}(respc)
 		return nil