Table of contents
1.
Introduction
2.
Docker Networking
2.1.
Networking Drivers in Docker
2.2.
Bridge Networking
2.3.
Overlay Networking
2.4.
Docker Network Commands
2.5.
Docker Compose and Networking
3.
Practical Example: WordPress with MySQL
4.
Types of Network Drivers
5.
Common Operations
6.
Frequently Asked Questions
6.1.
Q: Can I connect a container to multiple networks?
6.2.
Q: How can I secure my Docker networks?
6.3.
Q: What is the difference between Bridge and Host networking?
7.
Conclusion
Last Updated: Mar 27, 2024

Docker Networking

Author Gunjan Batra
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Introduction

Docker has revolutionized the way software is developed and deployed. A vital part of this ecosystem is Docker Networking, which governs how containers communicate with each other and with external systems. 

docker networking

This article will explore Docker Networking, its various types, and how to implement them.

Docker Networking

Docker Networking facilitates communication between Docker containers and other network endpoints. It abstracts complex network topology and makes it easy to connect containers running on the same host or different hosts.

Networking Drivers in Docker

Docker provides several built-in networking drivers to accommodate various use cases. The three primary networking drivers are:

  • Bridge Network: Used when containers need to communicate on the same Docker host.
     
  • Overlay Network: Useful for connecting multiple Docker daemons, typically in a Swarm cluster.
     
  • Host Network: Bypasses the Docker’s network stack and attaches to the host’s network directly.

Bridge Networking

Bridge networking is the default network type for containers. When Docker is installed, a new virtual bridge network is automatically created, and containers connect to it.

Creating a Bridge Network

docker network create --driver bridge my_custom_network

Connecting Containers to Bridge Network

docker run -d --name my_container --network my_custom_network my_image

Overlay Networking

Overlay networks enable swarm services to communicate with each other. It requires a key-value store like Consul or etcd and works across multiple hosts.

Creating an Overlay Network

docker network create -d overlay my_overlay

Host Networking

Host networking is useful when a container should not be isolated from the Docker host's network stack.

Running Container with Host Networking

docker run --network host my_image

Docker Network Commands

Here are some commonly used commands:

  • Inspect Network: docker network inspect NETWORK_NAME
     
  • List Networks: docker network ls
     
  • Remove Network: docker network rm NETWORK_NAME

Docker Compose and Networking

Docker Compose allows you to define multi-container applications. In the docker-compose.yml file, you can define networks as well.

version: '3'
services:
  web:
    image: nginx
    networks:
      - my_network
networks:
  my_network:
    driver: bridge

Also see,  Install Homebrew

Practical Example: WordPress with MySQL

A common use case for Docker networking is deploying WordPress with a MySQL container.

version: '3.1'
services:
  wordpress:
    image: wordpress
    ports:
      - 8080:80
    networks:
      - my_network
    environment:
      WORDPRESS_DB_HOST: db
  db:
    image: mysql
    environment:
      MYSQL_ROOT_PASSWORD: example
    networks:
      - my_network
networks:
  my_network:
    driver: bridge

Then, run docker-compose up, and WordPress will communicate with MySQL over the custom bridge network.

Types of Network Drivers

Network drivers are essential components that facilitate communication between an operating system and network hardware. Here are the various types of network drivers:

  • Ethernet Drivers: Used for wired network connections, typically found in local area networks (LANs). They handle data transmission over Ethernet cables.
  • Wi-Fi Drivers: Enable wireless networking. These drivers manage the connection and communication over Wi-Fi networks, handling tasks like signal strength and security protocols.
  • Bluetooth Drivers: Support wireless communication over short distances. They connect peripherals like mice, keyboards, and headsets to computers.
  • Virtual Network Drivers: Used in virtualized environments. They simulate network hardware and facilitate network operations in virtual machines.
  • WAN (Wide Area Network) Drivers: Designed for networks that span large geographical areas, like internet connections. They often handle higher latency and lower bandwidth compared to LAN drivers.
  • USB Network Drivers: Allow networking over USB interfaces. Useful for devices like USB Wi-Fi adapters or mobile phones using USB tethering.
  • Fibre Channel Drivers: Specialized drivers for high-speed networks, primarily used in storage area networks (SANs) for connecting servers to data storage facilities.

Common Operations

Docker networking involves various operations to manage the communication of Docker containers. Here are some everyday operations:

  • Creating Networks: Using docker network create, you can create custom communication networks for containers.
  • Inspecting Networks: A docker network inspection provides detailed information about a specific network, including connected containers and network configuration.
  • Listing Networks: docker network ls lists all networks currently available in the Docker environment.
  • Connecting Containers to Networks: Docker network connection allows you to attach a container to an existing network.
  • Disconnecting Containers from Networks: With docker network disconnect, you can detach a container from a network.
  • Removing Networks: docker network rm is used to delete no longer needed networks.
  • Port Mapping: Mapping ports from the container to the host system using -p or --publish in docker run to enable external access to the container.
  • Using Network Drivers: Docker supports network drivers like bridge, overlay, and macvlan for various networking scenarios.
  • Configuring DNS for Containers: Docker allows custom DNS settings for containers for resolving hostnames.
  • Setting Up Network Aliases: Using network aliases, containers can discover and communicate with each other using names instead of IP addresses.

Frequently Asked Questions

Q: Can I connect a container to multiple networks?


Yes, you can connect a container to multiple networks using the docker network connect command.

Q: How can I secure my Docker networks?

You can implement security by using firewalls, isolating containers, and using encrypted networks.

Q: What is the difference between Bridge and Host networking?


Bridge networking isolates containers within their network, while Host networking exposes containers to the host's network, without isolation.

Conclusion

Docker Networking plays a crucial role in container orchestration and the deployment of applications. It offers a flexible and easy-to-use framework for defining how containers interact with each other and external systems. By understanding different network types and how to implement them, developers can create scalable, efficient, and secure containerized applications. Whether deploying a single container or an entire microservices architecture, Docker Networking provides the essential tools to make it seamless.

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