Default Container Isolation: Containers are completely isolated from each other by default - they cannot communicate even if running on the same host machine
Multi-Container Architecture: Real-world applications often consist of multiple services (frontend, API, database) that need to communicate while remaining in separate containers
Docker Networks as Communication Bridges: Custom Docker networks (docker network create) enable container-to-container communication by providing a shared networking layer
Container Names as Hostnames: Within a Docker network, container names automatically become resolvable hostnames, enabling service discovery (e.g., http://node-server:3000)
Environment Variables for Configuration: Applications use environment variables to dynamically configure connection endpoints, making them adaptable to different deployment environments
Network Membership Requirement: All containers that need to communicate must be attached to the same custom network using the --network flag
Port Mapping vs Network Communication:
Port mapping (-p) exposes container ports to the host machine
Network communication allows direct container-to-container access without host involvement
Service Discovery Pattern: Applications reference other services by container name and internal port number, abstracting away the underlying network infrastructure
Package Management Consistency: Node.js uses package.json and npm install, similar to Python's requirements.txt and pip install - the patterns remain consistent across languages
Distributed Application Debugging: Connection errors between services often indicate network configuration issues rather than application code problems