How to Install Docker on Debian

Edited 1 week ago by ExtremeHow Editorial Team

DebianDockerContainersVirtualizationLinuxSoftware InstallationCLIOpen SourceDevOpsSystem Administration

Docker is a powerful tool used for developing, shipping, and running applications. It allows you to separate your applications from your infrastructure so you can deliver software faster. With Docker, you can manage your infrastructure the same way you manage your applications. By leveraging Docker's methodology for shipping, testing, and deploying code faster, you can significantly reduce the delay between writing code and running it in production. If you're using Debian, a popular Linux distribution, this guide will guide you through the steps to install Docker.

Prerequisites

Before you begin the installation process, you need to fulfill a few pre-requisites:

• You need a Debian 64-bit installation with root privileges.
• Make sure your Debian version is supported by Docker. Docker officially supports Debian 10 (Buster) and Debian 11 (Bullseye). Although Docker can work on older versions, it is not recommended.
• Internet connection is required to download Docker packages and dependencies.

Step 1: Update your system

Before installing new software, it is a good practice to update the existing list of packages and their respective versions. You can do this using the following command:

sudo apt-get update
sudo apt-get upgrade

These commands ensure that all your existing packages are up to date, reducing potential compatibility issues.

Step 2: Install the required packages

Docker requires certain packages to be installed on your system to work properly. Specifically, you need to install packages that allow your system to access repositories over HTTPS. Install these packages using the command:

sudo apt-get install apt-transport-https ca-certificates curl software-properties-common

Here is a brief description of what these packages do:

• apt-transport-https: Allows apt to use repositories accessed via HTTPS.
• ca-certificates: Provides common CA certificates to enable secure communications via SSL.
• curl: A tool for transferring data to or from a server, used here to download Docker's installation script.
• software-properties-common: Provides an abstraction of the used apt repositories and can be used to effectively manage additional repositories.

Step 3: Add Docker's official GPG key

Docker provides an official GPG key to ensure that the software you install from Docker is authentic and has not been tampered with. Add this key to your system by executing the following command:

curl -fsSL https://download.docker.com/linux/debian/gpg | sudo apt-key add -

This command downloads the GPG key from Docker's server and adds it to your system's list of trusted keys. The -fsSL option with curl ensures that the key is downloaded securely, while apt-key add - integrates it into the list.

Step 4: Set up the Docker repository

Next, set the Docker repository as a source from which you can download Docker directly. To add the Docker repository to your list of sources, use the following command:

sudo add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/debian $(lsb_release -cs) stable"

This command tells your package manager to use the Docker repository, automatically selecting the stable version for your current Debian release.

Step 5: Update the package database

After adding the Docker repository, update your package database to reflect recent changes and include the Docker packages:

sudo apt-get update

This refreshes your system's package index and includes the Docker repository so you can proceed with installing Docker.

Step 6: Install Docker

After the Docker repository is set up and your package database is updated, you are ready to install Docker. Execute the following command to install Docker:

sudo apt-get install docker-ce

docker-ce package represents the community edition of Docker, a freely available version with all the essential Docker features. This installation may prompt you for confirmation. Simply type "Y" and press Enter to continue the installation.

Step 7: Start and enable Docker

Once installed, Docker does not start automatically. To start the Docker service manually use the following:

sudo systemctl start docker

Additionally, to ensure that Docker starts when your system boots, enable the Docker service with the following command:

sudo systemctl enable docker

These commands ensure that your Docker engine is running and starts automatically upon system restart.

Step 8: Verify the Docker installation

To confirm that Docker is installed correctly, you can run a test container using the popular "hello-world" image. Run:

sudo docker run hello-world

If everything is set up correctly, this command will download the "hello-world" image from Docker Hub, create a new Docker container from the image, and display a message indicating that Docker is working. The output explains the steps to follow when setting up and running a Docker container, which confirms a successful Docker installation.

Additional configurations

When the Docker installation is complete, there are a few additional optional configurations you can consider:

1. Manage Docker as a non-root user

By default, Docker requires root privileges because it has broad system-level access. However, you can manage Docker as a non-root user by adding your user to the Docker group:

sudo usermod -aG docker $USER

After running the above commands, log out and log back in, or run newgrp docker to activate these changes. This setup facilitates Docker management without using sudo, reducing the chance of system-level mistakes.

2. Setting up Docker Compose

Docker Compose is a tool for running multi-container Docker applications. If your projects involve multiple services, Docker Compose helps to define and manage these clusters in an easy way. Here is how you can install Docker Compose:

sudo curl -L "https://github.com/docker/compose/releases/download/1.29.2/docker-compose-$(uname -s)-$(uname -m)" -o /usr/local/bin/docker-compose
sudo chmod +x /usr/local/bin/docker-compose

These commands download the docker-compose binary to your system and grant it execution permissions. Verify that Docker Compose is installed and configured correctly:

docker-compose --version

After successful installation, it will return the version of Docker Compose installed on your system.

Troubleshooting

During the installation process, you may encounter some problems. Here are some common troubleshooting tips:

• If Docker is not starting, make sure you have enabled and started the Docker service.
• If the Docker command requires root privileges, make sure your user is in the Docker group.
• Mismatched versions or packages marked as "paused" from upgrading may interfere with the installation. Make sure all packages are up-to-date.

Conclusion

In this guide, we have covered the steps required to install Docker on a Debian system. This includes setting up the prerequisites, adding the Docker repository, performing the installation, and verifying that everything works correctly with a test container. With Docker running on your system, you are now equipped to easily develop and deploy containerized applications, using the power of containerization to increase efficiency in your application lifecycle. Don't forget to check out Docker's documentation for more to fully utilize its versatile features.

As a next step, you can try building your custom Docker images, configuring Docker networking, or exploring orchestration tools like Kubernetes that further extend Docker's ability to run large-scale distributed applications. The adoption of container technology has immense potential for both developers and system administrators.

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