Use a JSON object for log tags, not an array

config/initializers/semantic_logger.rb

@@ -1,6 +1,10 @@
 if Rails.env.development? || Rails.env.production?
   Rails.application.configure do
-    config.log_tags = [:request_id] # Prepend all log lines with the following tags
+    # Prepend all log lines with the following tags
+    config.log_tags = {
+      request_id: :request_id,
+      some_other_tag: "some other value",
+    }
   end
 
   SemanticLogger.add_appender(io: $stdout, level: Rails.application.config.log_level, formatter: Rails.application.config.log_format)