Container Communication

Tutorial 2 of 4

Introduction

This tutorial aims to provide a comprehensive understanding of Docker container communication. By the end of this guide, you will have a clear idea of how Docker containers interact with each other and with the host system.

You will learn:
- How Docker networks facilitate container communication.
- Different networking options available in Docker.
- How to link containers.
- How to create and manage Docker networks.

Prerequisites:
- Basic understanding of Docker and its core concepts.
- Docker installed on your machine.

Step-by-Step Guide

Docker Networks

Docker Networking is a system by which Docker containers communicate. By default, every Docker container is assigned a network. This network allows Docker containers to communicate with each other and with the host system.

Types of Docker Networks

Docker supports several network types including bridge, host, overlay, none, and macvlan.

Bridge Network

This is the default network that Docker assigns to containers. Each container connected to a bridge network gets its IP address, allowing it to communicate with other containers on the same network.

Host Network

Containers that use the host network communicate directly with the host's network without any isolation, sharing the host's network interfaces.

Overlay Network

This network allows swarm services to communicate with each other, even if they are on different Docker hosts.

None Network

Containers attached to this network are isolated and have networking disabled.

Macvlan Network

This network allows Docker containers to be directly connected to the physical network using the MAC address, which is ideal for network-intensive applications.

Linking Containers

Containers can communicate with each other using links. This allows you to securely share environment variables and opens network paths between containers.

Code Examples

Creating a bridge network

# Create a bridge network named my_bridge
docker network create --driver bridge my_bridge

Running containers on a custom network

# Run a new container on my_bridge network
docker run -d --name my_container --network my_bridge nginx

Inspecting a Docker network

# Inspect my_bridge network
docker network inspect my_bridge

Linking two containers

# Run a new container and link it with my_container
docker run -d --name my_linked_container --link my_container:alias nginx

Summary

In this tutorial, we've covered the basics of Docker container communication, including Docker networks and linking containers. You've learned how to create and manage Docker networks and how to link containers for ease of communication.

Practice Exercises

Exercise 1:
Create a custom Docker network and run two containers on it. Check if they can communicate with each other.

Exercise 2:
Create two containers, one with a database (like MySQL) and another with a back-end application (like Node.js). Link these two containers and make the back-end application interact with the database.

Exercise 3:
Create a Docker network of type macvlan and run a container on it. Check the MAC address of the container and verify if it's directly connected to the physical network.

Next Steps

Continue to explore Docker's networking capabilities and try out different network types. Look into Docker's advanced networking features like network plugins and service discovery.