How to create a custom Docker bridge network

Introduction

Docker is a powerful containerization platform that allows you to package and deploy applications in a consistent and reproducible manner. One of the key features of Docker is its networking capabilities, which include the ability to create custom bridge networks. In this tutorial, you will learn how to create a custom Docker bridge network and connect containers to it, enabling secure and efficient communication between your application components.

Skills Graph

%%%%{init: {'theme':'neutral'}}%%%% flowchart RL docker(("`Docker`")) -.-> docker/ContainerOperationsGroup(["`Container Operations`"]) docker(("`Docker`")) -.-> docker/NetworkOperationsGroup(["`Network Operations`"]) docker/ContainerOperationsGroup -.-> docker/create("`Create Container`") docker/ContainerOperationsGroup -.-> docker/run("`Run a Container`") docker/ContainerOperationsGroup -.-> docker/inspect("`Inspect Container`") docker/NetworkOperationsGroup -.-> docker/network("`Manage Networks`") docker/ContainerOperationsGroup -.-> docker/ls("`List Containers`") subgraph Lab Skills docker/create -.-> lab-411523{{"`How to create a custom Docker bridge network`"}} docker/run -.-> lab-411523{{"`How to create a custom Docker bridge network`"}} docker/inspect -.-> lab-411523{{"`How to create a custom Docker bridge network`"}} docker/network -.-> lab-411523{{"`How to create a custom Docker bridge network`"}} docker/ls -.-> lab-411523{{"`How to create a custom Docker bridge network`"}} end

Understanding Docker Bridge Networks

Docker containers are designed to be lightweight and isolated, but they still need to communicate with each other and the outside world. Docker provides several networking options to facilitate this communication, one of which is the Docker bridge network.

A Docker bridge network is a virtual network that connects Docker containers running on the same host. It is the default network type for Docker containers, and it allows containers to communicate with each other using their container names or IP addresses.

When you start a new Docker container, it is automatically connected to the default bridge network, which is named bridge. This network is created by Docker and is managed by the Docker daemon. The bridge network is a good choice for simple use cases, but it has some limitations, such as the inability to easily connect containers across different hosts.

To overcome these limitations, you can create a custom Docker bridge network. A custom bridge network provides several benefits:

Improved Isolation: Containers connected to a custom bridge network are isolated from containers on the default bridge network, improving security and reducing the risk of unintended interactions.
Easier Container Linking: Containers on the same custom bridge network can communicate with each other using their container names, making it easier to set up and manage inter-container communication.
Network Segmentation: Custom bridge networks allow you to create separate networks for different parts of your application, improving network organization and security.
Improved Scalability: Custom bridge networks can be used to scale your application by allowing you to easily add new containers to the network.

To create a custom Docker bridge network, you can use the docker network create command. Once the custom network is created, you can connect containers to it using the --network flag when starting a new container or by connecting an existing container to the network using the docker network connect command.

graph LR A[Docker Host] --> B[Docker Daemon] B --> C[Default Bridge Network] B --> D[Custom Bridge Network] C --> E[Container 1] C --> F[Container 2] D --> G[Container 3] D --> H[Container 4]

In the diagram above, we can see the default bridge network and a custom bridge network created by the Docker daemon. Containers 1 and 2 are connected to the default bridge network, while Containers 3 and 4 are connected to the custom bridge network.

Creating a Custom Docker Bridge Network

To create a custom Docker bridge network, you can use the docker network create command. The basic syntax is as follows:

docker network create [OPTIONS] NETWORK

Here are the steps to create a custom Docker bridge network:

Step 1: Create a Custom Bridge Network

Open a terminal and run the following command to create a custom bridge network named "my-custom-network":

docker network create my-custom-network

This will create a new bridge network with the default settings.

Step 2: Verify the Network Creation

You can list all the available Docker networks using the docker network ls command:

docker network ls

The output should include the new "my-custom-network" bridge network.

Step 3: Customize the Network Configuration (Optional)

You can customize the network configuration by specifying additional options when creating the network. For example, to create a network with a specific subnet and gateway:

docker network create --subnet 172.18.0.0/16 --gateway 172.18.0.1 my-custom-network

This will create a custom bridge network with a specific subnet and gateway.

Step 4: Inspect the Network Details

You can inspect the details of the custom network using the docker network inspect command:

docker network inspect my-custom-network

This will display the network configuration, including the subnet, gateway, and other details.

By creating a custom Docker bridge network, you can improve the isolation, organization, and scalability of your Docker-based applications.

Connecting Containers to the Custom Network

After creating a custom Docker bridge network, you can connect containers to it. There are two ways to do this:

1. Connect a Container During Creation

When starting a new container, you can specify the --network flag to connect it to the custom network. For example, to start a new container and connect it to the "my-custom-network" network:

docker run -d --name my-app --network my-custom-network nginx

This will start a new Nginx container and connect it to the "my-custom-network" bridge network.

2. Connect an Existing Container

You can also connect an existing container to a custom network using the docker network connect command. For example, to connect an existing container named "my-app" to the "my-custom-network" network:

docker network connect my-custom-network my-app

After connecting the container to the custom network, you can access it from other containers on the same network using the container name or its IP address within the network.

graph LR A[Docker Host] --> B[Docker Daemon] B --> C[Custom Bridge Network] C --> D[Container 1] C --> E[Container 2] C --> F[Container 3]

In the diagram above, we can see three containers connected to the custom "my-custom-network" bridge network. These containers can communicate with each other using their container names or IP addresses within the network.

By connecting containers to a custom Docker bridge network, you can improve the isolation, organization, and scalability of your Docker-based applications.

Summary

In this tutorial, you have learned how to create a custom Docker bridge network, connect containers to it, and leverage the benefits of using a custom network for your Docker applications. By understanding and implementing custom Docker bridge networks, you can improve the security, isolation, and communication between your containerized services, leading to a more robust and scalable Docker-based infrastructure.