fixup

docker/fluentd/fluent.conf

@@ -6,9 +6,10 @@
 
 <filter **>
   @type record_transformer
+  enable_ruby true
   <record>
     level error
-    message ${record['log']}
+    message ${record['log'] || 'default log message'}
     timestamp ${time}
     service ${tag_parts[0]}
     container_image ${tag_parts[1]}