Docker Networking Explained with MySQL and Nginx Example

If you’ve ever wondered how Docker containers talk to each other, then this blog is for you!
Docker Networking allows containers to communicate securely and efficiently, just like systems in a real network.

In this blog, we’ll create a custom Docker network, connect multiple containers (MySQL and Nginx) to it, and verify that they can communicate….

Table of Contents

1. Introduction to Docker Networking

2. Step 1 — What is Docker Network?

3. Step 2 — Create a Custom Network

4. Step 3 — Run Containers on the Same Network

5. Step 4 — Verify Network Connections

6. Step 5 — Why Custom Networks Matter

7. Conclusion & Key Takeaways

1. Introduction to Docker Networking

Every Docker container is isolated by default — it has its own filesystem and network stack.
But when containers need to share data or communicate, Docker networking comes into play.

Docker provides different types of networks like:

• bridge (default)

• user defined bridge

• host

• none

• overlay

• macvlan

• ip

In this example, we’ll use a bridge network — a simple and commonly used type for single-host setups.

2. Step 1 — What is a Docker Network?

A Docker network acts as a virtual bridge that connects multiple containers so they can communicate using container names instead of IPs.

When containers are in the same network:

• They can communicate using container names (e.g., mysql).

• They remain isolated from other networks for better security.

3. Step 2 — Create a Custom Network

Let’s create a custom network named my-network.

docker network create my-network

Output Example:

b3a5a2d12c0a1c0eacb124a1f77e4f9cf2e67cb3b9cc83e7e4f7dc245a9cfd7b

Verify the network:

docker network ls

Now, we have successfully created a custom bridge network.

4. Step 3 — Run Containers on the Same Network

Run MySQL Container:

docker run -d --name mysql -e MYSQL_ROOT_PASSWORD=root --network=my-network mysql:latest

Run Nginx Container:

docker run -d -v mysql-data:/var -p 80:80 --network=my-network nginx:latest

Explanation:

5. Step 4 — Verify Network Connections

Now, let’s check if both containers are connected to the same network.

Command:

docker network inspect my-network

Example Output:

[
    {
        "Name": "my-network",
        "Id": "b3a5a2d12c0a1c0eacb124a1f77e4f9cf2e67cb3b9cc83e7e4f7dc245a9cfd7b",
        "Containers": {
            "2be185b15a7e": {
                "Name": "mysql",
                "IPv4Address": "172.18.0.2/16"
            },
            "9fd87cba456e": {
                "Name": "nginx",
                "IPv4Address": "172.18.0.3/16"
            }
        }
    }
]

✅ Result: Both containers are listed under the same network — my-network.
This means they can communicate using container names like:

ping mysql

or

ping nginx

6. Step 5 — Why Custom Networks Matter

7. Conclusion & Key Takeaways

• Docker networks connect containers just like a local network.

• Containers in the same network can communicate easily.

• Use custom networks for better security, organization, and flexibility.

• You can inspect, manage, and monitor these networks anytime using Docker commands.

Final Note

Now you’ve learned how to connect multiple containers using Docker networks — a must-know concept for any DevOps engineer!
Keep experimenting with other network types like host, overlay, and macvlan to level up your Docker skills.