Lesson 16 / 28

Connecting Containers

Create user-defined networks so containers reach each other by name instead of IP address.

docker network create

Containers on the same user-defined network resolve each other by container name through Docker's built-in DNS — no hardcoded IPs.

docker network create app-net
docker run -d --name db --network app-net postgres:16
docker run -d --name api --network app-net -e DB_HOST=db my-app:1.0
# inside 'api', http://db:5432 just works