Docker Compose — Services
Welcome to Chapter 4 — the heart of Docker Compose. Services are the core building block — each service defines a container that Compose manages.
Topics in This Chapter
| # | Topic | Description |
|---|---|---|
| 1 | Defining Services | Service structure, image, container_name, restart |
| 2 | Image vs Build | Using pre-built images vs building from Dockerfile |
| 3 | Ports and Expose | Publishing ports and internal expose |
| 4 | Command and Entrypoint | Overriding default commands |
| 5 | Service DNS Naming | How services discover each other |
What You’ll Learn
- How to define services with all common options
- When to use
image:vsbuild: - Port mapping in short and long form
- How to override container commands
- How service-to-service DNS works
Key Concept
Each service in your compose file becomes a running container with a DNS name:
┌─────────── compose.yml ───────────┐
│ │
│ services: │
│ web: ──→ Container "web" │
│ api: ──→ Container "api" │
│ db: ──→ Container "db" │
│ │
│ DNS Resolution: │
│ web → 172.18.0.2 │
│ api → 172.18.0.3 │
│ db → 172.18.0.4 │
└────────────────────────────────────┘
