Parse app config strictly by default (#3629)

Author: saquibmian

private/pkg/app/appext/appext.go

@@ -161,6 +161,25 @@ func BuilderWithLoggerProvider(loggerProvider LoggerProvider) BuilderOption {
 // If the file does not exist, this is a no-op.
 // The value should be a pointer to unmarshal into.
 func ReadConfig(container NameContainer, value interface{}) error {
+	configFilePath := filepath.Join(container.ConfigDirPath(), configFileName)
+	data, err := os.ReadFile(configFilePath)
+	if !errors.Is(err, os.ErrNotExist) {
+		if err != nil {
+			return fmt.Errorf("could not read %s configuration file at %s: %w", container.AppName(), configFilePath, err)
+		}
+		if err := encoding.UnmarshalYAMLStrict(data, value); err != nil {
+			return fmt.Errorf("invalid %s configuration file: %w", container.AppName(), err)
+		}
+	}
+	return nil
+}
+
+// ReadConfigNonStrict reads the configuration from the YAML configuration file config.yaml
+// in the configuration directory, ignoring any unknown properties.
+//
+// If the file does not exist, this is a no-op.
+// The value should be a pointer to unmarshal into.
+func ReadConfigNonStrict(container NameContainer, value interface{}) error {
 	configFilePath := filepath.Join(container.ConfigDirPath(), configFileName)
 	data, err := os.ReadFile(configFilePath)
 	if !errors.Is(err, os.ErrNotExist) {