docker-compose-networking

Service discovery in Docker Compose works automatically through network aliases. Define services on the same custom network and reference them by service name or explicit aliases in connection strings. Docker's embedded DNS server resolves these names to the correct container IP, enabling reliable inter-service communication without hardcoded addresses.

The default bridge network provides basic connectivity but no DNS resolution by service name. Custom bridge networks enable automatic DNS resolution, better isolation between service groups, and per-service network configuration. Custom networks are recommended for multi-container applications requiring controlled communication patterns.

Define multiple custom networks in your compose file and assign each service to specific networks using the networks key. Services on different networks cannot communicate directly unless explicitly connected to shared networks. This enforces security boundaries and allows frontend and backend services to operate in isolated network segments.

Yes, static IP addressing is supported within custom networks using ipv4_address. Assign fixed IPs to services that require consistent addresses for external system integration or load balancer configuration. This enables predictable networking for complex deployments while maintaining Docker Compose's declarative configuration.

Define external networks in your compose file with external: true and reference them in service network configurations. External networks allow Docker Compose services to communicate with containers or resources running outside the compose project, enabling integration with pre-existing infrastructure.

Host network mode directly exposes container ports on the host machine, bypassing Docker's network isolation. Use it only when performance is critical or when services require access to all host network interfaces. Bridge networks are preferred for scalability and security in multi-container applications.