Docker Networking – Connecting Containers Like a Pro
Learn how to connect Docker containers using networks for seamless communication.
1. Introduction
Docker networking allows containers to communicate with each other and the outside world.
Think of it like Wi-Fi for containers 📡—it enables seamless communication between services running in different containers.
In this guide, you'll learn how Docker networking works, how to expose ports, and how to connect multiple containers using a custom network. 🚀
2. Basics of Docker Networking
Docker provides different networking options:
| Network Type | Description |
| Bridge (default) | Containers on the same bridge network can communicate. |
| Host | Containers use the host machine’s network directly. |
| None | Completely isolates the container from any network. |
| Custom | User-defined networks for better container-to-container communication. |
3. Default Docker Bridge Network
By default, Docker containers run on the bridge network, allowing communication between containers on the same host.
Example: Running a Container on the Default Network
docker run -d --name mynginx nginx
Now, inspect the network:
docker network inspect bridge
✅ You’ll see that the container is connected to the default bridge network.
4. How to Expose Ports & Access Containers from the Host
By default, containers cannot be accessed from the host unless ports are exposed.
Exposing a Port
docker run -d -p 8080:80 nginx
Now, open localhost:8080 in your browser to access the container. 🎉
| Flag | Purpose |
-p 8080:80 | Maps port 80 (inside container) to 8080 (host machine). |
5. Creating and Using Custom Networks
For better container-to-container communication, create a custom network.
Step 1: Create a Network
docker network create mynetwork
Step 2: Run Containers on This Network
docker run -d --name webserver --network mynetwork nginx
docker run -d --name appserver --network mynetwork busybox sleep 3600
Step 3: Verify the Network
docker network inspect mynetwork
✅ Both containers can now communicate using their container names instead of IP addresses.
6. Connecting Multiple Containers Using a Docker Network
Let’s connect a web app container to a database container using a Docker network.
Step 1: Create a Network
docker network create myappnetwork
Step 2: Run a Database Container
docker run -d --name mydb --network myappnetwork -e MYSQL_ROOT_PASSWORD=root mysql
Step 3: Run a Web App Container
docker run -d --name myapp --network myappnetwork my-web-app
Step 4: Access the Database from the App
Inside the myapp container, connect to mydb using:
mysql -h mydb -u root -p
✅ The app can now communicate with the database securely inside the network! 🎉
7. Conclusion
Docker networking allows seamless container-to-container communication. Now you know how to:
✅ Use the default bridge network
✅ Expose ports to access containers
✅ Create and connect containers on custom networks
Try setting up a multi-container network today! 🚀