This document summarizes lessons learned from running large Docker environments in three or fewer sentences per section: 1. Dependencies between services can break architecture if not properly versioned. 2. A hardware defect in a single network card caused retransmissions under heavy load, affecting inter-container communication. 3. Logs from containers consumed all disk space when log management was not configured, preventing new containers from running. 4. Slowdowns occurred when a orchestration system stored excessive versions of services due to configuration. 5. Massive load testing exposed dependencies between over 800 billion components, requiring automation to analyze problems at scale.