As distributed systems become more complex, it can be useful to have tools that help you understand how your system is behaving in production. Packetbeat is an open source tool which uses agents to sniff traffic between nodes, allowing you to see traffic patterns, error rates and other useful information. It requires Elasticsearch and Kibana to work, but if you are already using these tools as part of log aggregation, it could be an easy drop-in to give you more insight into your production system.