How to Install and Use Docker on Debian 11

If you're new to Debian and want to get started with the basics of creating new user, firewall etc. You can check our Getting started guide.

Installing Docker

First, update your existing list of packages:

apt update

Next, install a few prerequisite packages which lets apt use packages over HTTPS:

apt install apt-transport-https ca-certificates curl gnupg2 software-properties-common

Then add the GPG key for the official Docker repository to your system:

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

Output:

[email protected]:~# curl -fsSL https://download.docker.com/linux/debian/gpg | sudo apt-key add -

Add the Docker repository to APT sources:

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

Next, update the package database with the Docker packages from the newly added repo:

apt update

Make sure you are about to install from the Docker repo instead of the default Debian repo:

apt-cache policy docker-ce

Output:

[email protected]:~# apt-cache policy docker-ce
  docker-ce:
  Installed: (none)
  Candidate: 5:20.10.8~3-0~debian-bullseye
rsion table: 5:20.10.8~3-0~debian-bullseye 500
             500 https://download.docker.com/linux/debian bullseye/stable amd64 Packages
             5:20.10.7~3-0~debian-bullseye 500
             500 https://download.docker.com/linux/debian bullseye/stable amd64 Packages
             5:20.10.6~3-0~debian-bullseye 500
             500 https://download.docker.com/linux/debian bullseye/stable amd64 Packages

Notice that docker-ce is not installed.

Finally, install Docker:

apt install docker-ce

Output:

[email protected]:~# apt install docker-ce
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
The following additional packages will be installed:
containerd.io docker-ce-cli docker-ce-rootless-extras
docker-scan-plugin git git-man liberror-perl libltdl7 libslirp0
patch pigz slirp4netns

Docker is now installed, the daemon started, and the process enabled to start on boot.

And to check if thats active:

systemctl status docker

Output:

[email protected]:~#
● docker.service - Docker Application Container Engine
     Loaded: loaded (/lib/systemd/system/docker.service; enabled; vendor preset: enabled)
     Active: active (running) since Wed 2021-08-04 15:02:12 GMT; 1min 2s ago
TriggeredBy: ● docker.socket
       Docs: https://docs.docker.com
   Main PID: 76508 (dockerd)
      Tasks: 12
     Memory: 36.3M
        CPU: 566ms
     CGroup: /system.slice/docker.service
             └─76508 /usr/bin/dockerd -H fd:// --containerd=/run/containerd/containerd.sock

Executing the Docker Command Without Sudo

Add a new user in Debian

adduser user1 or useradd user1

If you want to avoid typing sudo whenever you run the docker command, add your username to the docker group:

usermod -aG docker user1

To apply the new group membership, log out of the server and back in, or type the following:

su - user1

Confirm that your user is now added to the docker group by typing:

id -nG

Output:

$ id -nG
user1 docker

Using the Docker Command

Using docker consists of passing it a chain of options and commands followed by arguments. The syntax takes this form:

docker [option] [command] [arguments]

To view all available subcommands, type:

docker

Output:

Commands:
app*        Docker App (Docker Inc., v0.9.1-beta3)
builder     Manage builds
buildx*     Build with BuildKit (Docker Inc., v0.6.1-docker)
config      Manage Docker configs
container   Manage containers
context     Manage contexts
image       Manage images
manifest    Manage Docker image manifests and manifest lists
network     Manage networks
node        Manage Swarm nodes
plugin      Manage plugins
scan*       Docker Scan (Docker Inc., v0.8.0)

To view system-wide information about Docker, use:

docker info

Output:

[email protected]:~# docker info
 Client:
 Context:    default
 Debug Mode: false
 Plugins:
  app: Docker App (Docker Inc., v0.9.1-beta3)
  buildx: Build with BuildKit (Docker Inc., v0.6.1-docker)
  scan: Docker Scan (Docker Inc., v0.8.0)

Working with Docker Images

To check whether you can access and downloaded images from Docker Hub, run the below command:

docker run hello-world

Output:

[email protected]:~#docker run hello-world
Unable to find image 'hello-world:latest' locally
latest: Pulling from library/hello-world
b8dfde127a29: Pull complete 
Digest: sha256:df5f5184104426b65967e016ff2ac0bfcd44ad7899ca3bbcf8e44e4461491a9e
Status: Downloaded newer image for hello-world:latest

Docker was initially unable to find the hello-world image locally, so it downloaded the image from Docker Hub, which is the default repository.

You can search for images available on Docker Hub by using the docker command with the search subcommand. For example, to search for the Debian image, type:

docker search debian

Output:

[email protected]:~# docker search debian
NAME                                               DESCRIPTION                                     STARS     OFFICIAL     AUTOMATED
ubuntu                                             Ubuntu is a Debian-based Linux operating sys…   12586     [OK]       
debian                                             Debian is a Linux distribution that's compos…   3934      [OK]       
arm32v7/debian                                     Debian is a Linux distribution that's compos…   72                   
itscaro/debian-ssh                                 debian:jessie                                   28                   [OK]

To download the official debian image to your computer:

docker pull debian

Output:

[email protected]:~# docker pull debian
Using default tag: latest
latest: Pulling from library/debian
Digest: sha256:cc58a29c333ee594f7624d968123429b26916face46169304f07580644dde6b2
Status: Image is up to date for debian:latest
docker.io/library/debian:latest

To see the images that have been downloaded to your computer, run the below command:

docker images

Output:

[email protected]:~# docker images
REPOSITORY    TAG       IMAGE ID       CREATED        SIZE
debian        latest    0980b84bde89   13 days ago    114MB
hello-world   latest    d1165f221234   5 months ago   13.3kB

Running a Docker Container

Let's run a container using the latest image of Debian:

docker run -it debian

Output:

[email protected]:~# docker run -it debian
[email protected]:/# 

Now you can run any command inside the container. For example, let's update the package database inside the container

apt update

Output:

[email protected]:/# apt update
Get:1 http://deb.debian.org/debian buster InRelease [122 kB]
Get:2 http://security.debian.org/debian-security buster/updates InRelease [65.4 kB]

Then install any application in it. Let's install Node.js:

[email protected]:/# apt install nodejs

This installs Node.js in the container from the official Debian repository. When the installation finishes, verify that Node.js is installed:

node -v

Output:

[email protected]:/# node -v
v10.24.0

Managing Docker Containers

After using Docker for a while, you'll have many active (running) and inactive containers on your computer. To view the active ones, use:

docker ps

Output:

[email protected]:~$ docker ps
CONTAINER ID   IMAGE     COMMAND   CREATED   STATUS    PORTS     NAMES

To view all containers — active and inactive, run docker ps with the -a switch:

docker ps -a

Output:

[email protected]:~$ docker ps -a
CONTAINER ID   IMAGE         COMMAND    CREATED          STATUS                      PORTS     NAMES
5a4a39b56450   debian        "bash"     4 minutes ago    Exited (0) 2 minutes ago              hardcore_austin
00f27dc84bf6   hello-world   "/hello"   18 minutes ago   Exited (0) 18 minutes ago             relaxed_euclid

To view the latest container you created, pass it the -l switch:

docker ps -l

Output:

[email protected]:~$ docker ps -l
CONTAINER ID   IMAGE     COMMAND   CREATED         STATUS                     PORTS     NAMES
5a4a39b56450   debian    "bash"    5 minutes ago   Exited (0) 2 minutes ago             hardcore_austin

To start a stopped container, use docker start, followed by the container ID or the container's name

docker start 5a4a39b56450

Output:

[email protected]:~$ docker start 5a4a39b56450
5a4a39b56450

To view the latest container:

[email protected]:~$ docker ps

Output:

[email protected]:~$ docker ps
CONTAINER ID   IMAGE     COMMAND   CREATED         STATUS         PORTS     NAMES
5a4a39b56450   debian    "bash"    8 minutes ago   Up 2 minutes             hardcore_austin

To stop a running container, use docker stop, followed by the container ID or name.

docker stop hardcore_austin

Once you've decided you no longer need a container anymore, remove it with the docker rm command, again using either the container ID or the name.

docker rm hardcore_austin