Networking

Docker creates a software-defined network layer that controls how containers communicate with each other and the outside world. This module covers network drivers, port publishing, DNS-based service discovery, Compose networking, and troubleshooting connectivity issues.

How Docker Networking Works

flowchart TD
    subgraph Host["Docker Host"]
        subgraph Bridge["User-Defined Bridge Network"]
            A["Container A<br/>(web)"] <-->|"DNS: api"| B["Container B<br/>(api)"]
            B <-->|"DNS: db"| C["Container C<br/>(db)"]
        end
        P["Published Port<br/>Host:8080 → web:80"]
    end
    Internet <-->|"Port 8080"| P
    P <--> A

    style Bridge fill:#e3f2fd,stroke:#1565c0
    style P fill:#fff3e0,stroke:#ef6c00

What You Will Learn

Lesson	What It Covers
Network Drivers	Bridge, host, none, and macvlan -- when to use each
Port Publishing	Exposing container services to the host and outside world
DNS and Service Discovery	How containers find each other by name
Networking with Compose	Designing network topology in multi-service stacks
Troubleshooting	Diagnosing connectivity failures step by step

Prerequisites

• Have Docker Engine installed (Module 2)
• Understand containers and docker run (Module 4)