How to Install Docker on Debian 12

Introduction

Docker is an open-source platform that enables you to build, package, and deploy applications to multiple platforms or environments using containers. Containers include the necessary dependencies, libraries, code, and runtime that enable your applications to run consistently in multiple environments.

This article explains how to install Docker on Debian 12 and run containerized applications on your server. You will deploy container images and integrate a container registry such as the Vultr Container Registry to store your container images.

Prerequisites

Before you begin:

• Deploy a Debian 12 instance on Vultr.
• Access to the server using SSH as a non-root user with sudo privileges.
• Create a Vultr Container Registry to store your Docker images.

Install Docker

Docker is available in the default package repositories on Debian 12, but the available package versions may not be the latest. Follow the steps below to add the official Docker repository to your Debian package sources and install the latest Docker version on your server.

1. Update the server's package index.

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   $ sudo apt update

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2. Install the necessary dependency packages on your server.

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   $ sudo apt install ca-certificates curl

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3. Add the Docker GPG key to your server's keyrings.

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   $ sudo curl -fsSL https://download.docker.com/linux/debian/gpg -o /etc/apt/keyrings/docker.asc

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4. Add the latest Docker repository information to your APT sources list.

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   $ echo "deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.asc] https://download.docker.com/linux/debian $(. /etc/os-release && echo "$VERSION_CODENAME") stable" | sudo tee /etc/apt/sources.list.d/docker.list > /dev/null

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5. Update the server's package index to apply the new repository changes.

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   $ sudo apt update

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6. Install Docker and all necessary add-on packages such as containerd.io

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   $ sudo apt install docker-ce docker-ce-cli containerd.io -y

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7. View the installed Docker version on your server.

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   $ docker --version

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   Your output should be similar to the one below.

   Docker version 27.0.3, build 7d4bcd8

Manage the Docker System Service

Docker uses the docker system service to manage the daemon runtime and processes on your server. Follow the steps below to manage the Docker system service, enable it to start at system boot, and add your non-root user to the docker group to run CLI commands without sudo privileges.

1. Enable the Docker service to automatically at system boot.

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   $ sudo systemctl enable docker

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   Output:

   Synchronizing state of docker.service with SysV service script with /lib/systemd/systemd-sysv-install.
   Executing: /lib/systemd/systemd-sysv-install enable docker

2. View the Docker service status and verify that it's running on your server.

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   $ sudo systemctl status docker

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   Output:

   ● docker.service - Docker Application Container Engine
      Loaded: loaded (/lib/systemd/system/docker.service; enable>
      Active: active (running) since Mon 2024-07-01 18:39:27 UTC>
   TriggeredBy: ● docker.socket
      Docs: https://docs.docker.com
   Main PID: 4050 (dockerd)
      Tasks: 7
      Memory: 32.9M
      CPU: 483ms
      CGroup: /system.slice/docker.service
      └─4050 /usr/bin/dockerd -H fd:// --containerd=/run>

3. Stop the Docker service.

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   $ sudo systemctl stop docker

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   Output:

   Warning: Stopping docker.service, but it can still be activated by:
   docker.socket

4. Restart the Docker service.

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   $ sudo systemctl start docker

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5. Add your non-root user to the Docker group to run Docker CLI commands without sudo privileges. Replace linuxuser with your actual username.

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   $ sudo usermod -aG docker linuxuser

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6. Enable the new user group changes in your active session.

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   $ newgrp docker

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Deploy Containerized Applications using Docker

Docker runs applications using container images on your server. Follow the steps below to use Docker CLI and pull a sample hello-world container image from the Docker Hub registry to deploy on your server.

1. Pull the hello-world container image from Docker Hub.

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   $ docker pull hello-world

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   Output:

   Using default tag: latest
   latest: Pulling from library/hello-world
   c1ec31eb5944: Pull complete 

2. View all Docker images on your server and verify that the hello-world image is available.

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   $ docker images

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   Output:

   REPOSITORY    TAG       IMAGE ID       CREATED         SIZE
   hello-world   latest    d2c94e258dcb   14 months ago   13.3kB

3. Deploy a new containerized application using the hello-world image.

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   $ sudo docker run hello-world

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   Output:

   Hello from Docker!
   This message shows that your installation appears to be working correctly.

4. List all Docker processes and verify that your hello-world container runs, but exits.

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   $ sudo docker ps -a

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   Output:

   CONTAINER ID   IMAGE         COMMAND    CREATED              STATUS                          PORTS     NAMES
   4f979e715721   hello-world   "/hello"   About a minute ago   Exited (0) About a minute ago             festive_curran

5. Run the following command to stop a running container using its ID. For example, 4f979e715721.

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   $ sudo docker stop 4f979e715721

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6. Use the rm option to delete a container.

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   $ sudo docker rm 4f979e715721

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Login to a Container Registry

A container registry enables the storage, management, and shipping of container images to multiple environments depending on your needs. Docker integrates with registries such as the Vultr Container Registry to build, store, and deploy container images on your server. Follow the steps below to log in and use your Vultr Container Registry with Docker.

1. Open your Vultr Container Registry's management page using the Vultr Console to access your registry credentials.

2. Log in to your Vultr Container Registry using the docker login command. Replace the following example values with your actual registry credentials.

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   $ sudo docker login https://ewr.vultrcr.com/examplereg -u example-user -p example-vcr-api

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   Your output should be similar to the one below when successful.

   WARNING! Using --password via the CLI is insecure. Use --password-stdin.
   WARNING! Your password will be stored unencrypted in /home/hum/.docker/config.json.
   Configure a credential helper to remove this warning. See
   https://docs.docker.com/engine/reference/commandline/login/#credential-stores
   
   Login Succeeded

3. List all Docker images available on your server.

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   $ docker images

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   Output:

   REPOSITORY    TAG       IMAGE ID       CREATED         SIZE
   hello-world   latest    d2c94e258dcb   14 months ago   13.3kB

   The hello-world image is available on your server based on the above output, use the image to tag and verify push access to your Vultr Container Registry.

4. Tag the local hello-world Docker image with your desired Vultr Container Registry tag. For example, ewr.vultrcr.com/examplereg/hello-world:latest.

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   $ docker tag hello-world:latest ewr.vultrcr.com/examplereg/hello-world:latest

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5. List all Docker images available on your server.

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   $ docker images

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   Verify that the new tagged image is available similar to the following output.

   REPOSITORY                            TAG       IMAGE ID       CREATED         SIZE
   hello-world                           latest    d2c94e258dcb   14 months ago   13.3kB
   ewr.vultrcr.com/examplereg/hello-world   latest    d2c94e258dcb   14 months ago   13.3kB

6. Push the tagged image to your Vultr Container Registry.

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   $ docker push ewr.vultrcr.com/examplereg/hello-world

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   Your output should be similar to the one below when successful.

   Using default tag: latest
   The push refers to repository [ewr.vultrcr.com/examplereg/hello-world]
   ac28800ec8bb: Pushed 
   latest: digest: sha256:d37ada95d47ad12224c205a938129df7a3e52345828b4fa27b03a98825d1e2e7 size: 524

7. Access your Vultr Container Registry's management page, navigate to the Repositories tab and verify that the new Docker image repository is available.

   

8. Deploy a new container application using the Docker image from your Vultr Container Registry.

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   $ docker run ewr.vultrcr.com/testreg/hello-world

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   Output:

   Hello from Docker!
   This message shows that your installation appears to be working correctly.

Conclusion

You have installed Docker on your Debian 12 server and deployed a sample containerized application. Docker enables you to build and deploy multiple applications, bind specific host ports to your container ports, and securely access the containerized applications. For more information and configuration options, visit the official Docker documentation.