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Docker Tutorial — Part 5: Networking Basics

Containers do not live alone. They talk to databases, APIs, and other services. Docker networking makes this possible.

Default Docker Network

Docker automatically creates a bridge network. All containers can communicate inside it.

List Docker Networks

docker network ls

Create Custom Network

docker network create mynetwork

Run Containers in Same Network

docker run -d --name backend --network mynetwork nginx
docker run -d --name frontend --network mynetwork nginx

Now containers can talk using container names:

curl http://backend

Why Custom Networks Matter

• Clean service isolation
• Easy container-to-container communication
• Required for microservices

Port Mapping (Host Access)

docker run -d -p 8080:80 nginx

This maps host port 8080 to container port 80.

Security Tip

Only expose ports that are required. Every open port is a risk.

Next, we move towards multi-container setups using Docker Compose.