Docker Networking

Containers usually need network communication.

Examples:

• web server ↔ database
• API ↔ Redis
• reverse proxy ↔ backend

Docker provides virtual networking.

Default Bridge Network

By default, Docker creates:

bridge

network.

Containers connected to bridge can communicate internally.

Visual Network Example

+-------------------+
| Docker Host       |
|                   |
|  +-------------+  |
|  | nginx       |  |
|  +-------------+  |
|         ↓         |
|  +-------------+  |
|  | postgres    |  |
|  +-------------+  |
+-------------------+

Port Mapping

Containers are isolated.

To expose services externally:

docker run -p 8080:80 nginx

Breakdown:

Access:

http://localhost:8080

Listing Networks

docker network ls

Inspect network:

docker network inspect bridge

Creating Custom Networks

docker network create mynetwork

Run container inside network:

docker run --network mynetwork nginx

Custom networks improve:

• isolation
• service discovery
• organization