Using Docker Contexts for Remote Management

1. Introduction

Goal

This tutorial aims to help you understand Docker Contexts, a feature that allows you to switch between different Docker environments.

Learning Outcomes

By the end of this tutorial, you will be able to create, manage, and use Docker Contexts to switch between various Docker environments seamlessly.

Prerequisites

Before starting this tutorial, you need to have Docker installed on your system. If you're not familiar with Docker, you might want to have a basic understanding of Docker and Docker commands.

2. Step-by-Step Guide

Docker Contexts are a great way to manage multiple Docker environments. You can think of a Docker context as a configuration for connecting to a specific Docker daemon.

Creating a Docker context

To create a Docker context, we use the docker context create command. The basic syntax goes like this:

docker context create [OPTIONS] CONTEXT

The OPTIONS can be many things, but the most common are -d, --description string to provide a description for the context, and --docker string, to set the Docker endpoint.

For example:

docker context create --description "This is my first Docker context" myFirstContext

Listing Docker contexts

To list all available Docker contexts, we use the docker context ls command:

docker context ls

Using a Docker context

To use a specific Docker context, we use the docker context use command:

docker context use myFirstContext

3. Code Examples

Let's go through a practical example of creating a Docker context, listing contexts, and using a context.

Creating a Docker context

# Create a Docker context
docker context create --description "This is my first Docker context" myFirstContext

This command creates a Docker context named myFirstContext.

Listing Docker contexts

# List all Docker contexts
docker context ls

When you run this command, you should see a list of all Docker contexts. myFirstContext should be one of them.

Using a Docker context

# Use a specific Docker context
docker context use myFirstContext

This command sets the Docker context to myFirstContext. All subsequent Docker commands will use this context.

4. Summary

In this tutorial, you've learned how to create, list, and use Docker contexts. Docker Contexts are a powerful feature that allows you to switch between different Docker environments easily.

For further learning, you can look into how to remove Docker contexts (docker context rm) and how to inspect Docker contexts (docker context inspect).

5. Practice Exercises

1. Create a new Docker context with your own description.
2. Switch to the Docker context you created.
3. List all Docker contexts and confirm that the one you created is there.

Solutions

1. docker context create --description "My second Docker context" mySecondContext
2. docker context use mySecondContext
3. docker context ls - You should see mySecondContext in the list.

Keep practicing with Docker contexts, and try using them with different Docker environments!