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Lesson 07 / 11
Networking
Docker ships several network drivers; two cover almost everything you'll do:
- bridge (default) — a private, isolated network on the host. Each container gets its own IP; containers reach each other only if they're on the same bridge network.
- host — the container shares the host's network namespace directly. No port mapping needed, but also no isolation (Linux only).
Bridge: each container gets its own private IP, reached via published ports. Host: no isolation, no port mapping needed.
# create a user-defined bridge network docker network create app-net docker run -d --name db --network app-net postgres:16 docker run -d --name api --network app-net myapp:1.0 docker network ls docker network inspect app-net
User-defined networks > the default bridge: containers on a user-defined network get automatic DNS resolution by name. The legacy default bridge doesn't give you that without the deprecated
--link flag — always create your own network.Try it yourselfRun two containers with
--network app-net, then from one, ping the other by container name. Then remove --network app-net and try again — watch it fail without a shared user-defined network.