In this guide, we want to teach you How To Install and Use Docker on Ubuntu 22.04.
Docker is an open-source platform that enables developers to build, deploy, run, update and manage containers—standardized, executable components that combine application source code with the operating system (OS) libraries and dependencies required to run that code in any environment.
Steps To Install and Use Docker on Ubuntu 22.04
To complete this guide, you must log in to your server as a non-root user with sudo privileges. To do this, you can follow our guide the Initial Server Setup with Ubuntu 22.04.
Also in the article, you will need to create an account on DockerHub to create your own images and push them to Docker Hub.
Download and Add the Docker Repository key on Ubuntu 22.04
First, you need to update your local package index with the command below:
sudo apt update
Then, you need to install a few required packages which let apt use packages over HTTPS, run the following command:
sudo apt install apt-transport-https ca-certificates curl software-properties-commonNow you should add the GPG key for the official Docker repository to your system with the following command:
curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo gpg --dearmor -o /usr/share/keyrings/docker-archive-keyring.gpgNext, use the command below to add the Docker repo on Ubuntu 22.04:
echo "deb [arch=$(dpkg --print-architecture) signed-by=/usr/share/keyrings/docker-archive-keyring.gpg] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable" | sudo tee /etc/apt/sources.list.d/docker.list > /dev/nullUpdate your local package index again:
sudo apt updateInstalling Docker on Ubuntu 22.04
At this point, you need to be sure about installing from the Docker repository instead of the default Ubuntu repository:
apt-cache policy docker-ce
In your output you will see something like this:
Output
docker-ce:
Installed: (none)
Candidate: 5:20.10.18~3-0~ubuntu-jammy
Version table:
5:20.10.18~3-0~ubuntu-jammy 500
500 https://download.docker.com/linux/ubuntu jammy/stable amd64 Packages
5:20.10.17~3-0~ubuntu-jammy 500
...Now the docker-ce candidates to install. Install Docker on Ubuntu 22.04 with the following command:
sudo apt install docker-ce
When the installation is completed, check that is active and running on Ubuntu 22.04 with the following command:
sudo systemctl status docker
Your output should be similar to this:
Output
● docker.service - Docker Application Container Engine
Loaded: loaded (/lib/systemd/system/docker.service; enabled; vendor preset>
Active: active (running) since Thu 2022-09-29 06:30:04 UTC; 7s ago
TriggeredBy: ● docker.socket
Docs: https://docs.docker.com
Main PID: 3312 (dockerd)
Tasks: 8
Memory: 23.0M
CPU: 376ms
CGroup: /system.slice/docker.service
└─3312 /usr/bin/dockerd -H fd:// --containerd=/run/containerd/contNow you have installed Docker on Ubuntu 22.04. It will give you the Docker service, Also as, the docker command-line utility.
Add User To Docker Group
As you know, you need sudo privileges to run docker commands. Or if you don’t want to use sudo, you can add a user to the docker group. In this way, the user can run commands without using sudo.
To add a user to the docker group run the following command:
sudo usermod -aG docker ${USER}
You can log out and back into the server with the same user.
If you want to add a user that you aren’t logged in with, run the following command:
sudo usermod -aG docker username
For the rest of the article, we run commands as a user in the docker group.
How to Use the Docker command on Ubuntu 22.04
At this point, you have installed Docker on Ubuntu 22.04. Now let’s know about the docker command.
The syntax of using the docker command is like this:
docker [option] [command] [arguments]
You can list all available subcommands by typing the following command:
docker
Your output should be like this:
Output
Options:
--config string Location of client config files (default
"/root/.docker")
-c, --context string Name of the context to use to connect to the
daemon (overrides DOCKER_HOST env var and
default context set with "docker context use")
-D, --debug Enable debug mode
-H, --host list Daemon socket(s) to connect to
-l, --log-level string Set the logging level
("debug"|"info"|"warn"|"error"|"fatal")
(default "info")
--tls Use TLS; implied by --tlsverify
--tlscacert string Trust certs signed only by this CA (default
"/root/.docker/ca.pem")
--tlscert string Path to TLS certificate file (default
"/root/.docker/cert.pem")
--tlskey string Path to TLS key file (default
"/root/.docker/key.pem")
--tlsverify Use TLS and verify the remote
-v, --version Print version information and quit
Management Commands:
app* Docker App (Docker Inc., v0.9.1-beta3)
builder Manage builds
buildx* Docker Buildx (Docker Inc., v0.9.1-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., v0.17.0)
secret Manage Docker secrets
service Manage services
stack Manage Docker stacks
swarm Manage Swarm
system Manage Docker
trust Manage trust on Docker images
volume Manage volumes
Commands:
attach Attach local standard input, output, and error streams to a running container
build Build an image from a Dockerfile
commit Create a new image from a container's changes
cp Copy files/folders between a container and the local filesystem
create Create a new container
diff Inspect changes to files or directories on a container's filesystem
events Get real time events from the server
exec Run a command in a running container
export Export a container's filesystem as a tar archive
history Show the history of an image
images List images
import Import the contents from a tarball to create a filesystem image
info Display system-wide information
inspect Return low-level information on Docker objects
kill Kill one or more running containers
load Load an image from a tar archive or STDIN
login Log in to a Docker registry
logout Log out from a Docker registry
logs Fetch the logs of a container
pause Pause all processes within one or more containers
port List port mappings or a specific mapping for the container
ps List containers
pull Pull an image or a repository from a registry
push Push an image or a repository to a registry
rename Rename a container
restart Restart one or more containers
rm Remove one or more containers
rmi Remove one or more images
run Run a command in a new container
save Save one or more images to a tar archive (streamed to STDOUT by default)
search Search the Docker Hub for images
start Start one or more stopped containers
stats Display a live stream of container(s) resource usage statistics
stop Stop one or more running containers
tag Create a tag TARGET_IMAGE that refers to SOURCE_IMAGE
top Display the running processes of a container
unpause Unpause all processes within one or more containers
update Update configuration of one or more containers
version Show the Docker version information
wait Block until one or more containers stop, then print their exit codes
Run 'docker COMMAND --help' for more information on a command.
To get more help with docker, check out our guides at https://docs.docker.com/go/guides/
To get more information you can run the following command:
docker docker-subcommand --help
To view system-wide information about Docker, use:
docker info
When you get to know about the docker command on Ubuntu 22.04. let’s see how to work with them.
Work with Docker Images
Docker containers are built from Docker images. By default, Docker pulls these images from Docker Hub. Anyone can host their Docker images on Docker Hub, so most applications and Linux distributions you’ll need will have images hosted there.
To check that you can access and download images from Docker Hub, run the following command:
docker run hello-world
Your output should seem like this:
Output
Unable to find image 'hello-world:latest' locally
latest: Pulling from library/hello-world
2db29710123e: Pull complete
Digest: sha256:62af9efd515a25f84961b70f973a798d2eca956b1b2b026d0a4a63a3b0b6a3f2
Status: Downloaded newer image for hello-world:latest
Hello from Docker!
This message shows that your installation appears to be working correctly.
To generate this message, Docker took the following steps:
1. The Docker client contacted the Docker daemon.
2. The Docker daemon pulled the "hello-world" image from the Docker Hub.
(amd64)
...
Now you can search for available images on Docker Hub, for example, run the following command to search ubuntu images:
docker search ubuntu
In the output you will see something similar to this:
Output
NAME DESCRIPTION STARS OFFICIAL AUTOMATED
ubuntu Ubuntu is a Debian-based Linux operating sys… 15005 [OK]
websphere-liberty WebSphere Liberty multi-architecture images … 289 [OK]
ubuntu-upstart DEPRECATED, as is Upstart (find other proces… 112 [OK]
neurodebian NeuroDebian provides neuroscience research s… 93 [OK]
ubuntu/nginx Nginx, a high-performance reverse proxy & we… 61
open-liberty Open Liberty multi-architecture images based… 55 [OK]
ubuntu-debootstrap DEPRECATED; use "ubuntu" instead 46 [OK]
...
Here, when you choose the image that you want to use, you can run the following command to download the image:
docker pull ubuntu
You will see the following output:
Output
Using default tag: latest
latest: Pulling from library/ubuntu
2b55860d4c66: Pull complete
Digest: sha256:20fa2d7bb4de7723f542be5923b06c4d704370f0390e4ae9e1c833c8785644c1
Status: Downloaded newer image for ubuntu:latest
docker.io/library/ubuntu:latest
After you downloaded the image, you can run a container with that image with the “run” subcommand. If an image wasn’t downloaded the “run” subcommand downloaded it first then run the container using it.
To see images you have downloaded, run the following command:
docker images
You will see something like this:
Output
REPOSITORY TAG IMAGE ID CREATED SIZE
ubuntu latest 2dc39ba059dc 3 weeks ago 77.8MB
hello-world latest feb5d9fea6a5 12 months ago 13.3kB
At this point, you learn how to work with Docker images on Ubuntu 22.04. Now let’s see how to run Docker containers.
Run Docker Containers
Here you can run a container using the latest image of Ubuntu with the following command:
docker run -it ubuntu
Note: -it switches give you interactive shell access into the container.
Your command prompt should change to this form:
[email protected]:/#
Important Note: Remember the container id in the command prompt. In this example, the container ID is 1233a80158d9.
Now you can run any commands that you want. You don’t need to use sudo for your commands because you run commands as a root inside the container.
[email protected]:/# apt update
Here you can install any application. Here we install Node.js with the following command:
[email protected]:/# apt install nodejs
Note: Any changes you make inside the container only apply to that container.
You can exit from the container by the following command:
[email protected]:/# exit
When you are finished running Docker containers on Ubuntu 22.04 let’s see how to manage them.
Manage Docker containers
You can see active and running containers with the following command:
docker ps
Output
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
To list all containers both active and inactive, use the following command;
docker ps -a
In your output you will see:
Output
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
1233a80158d9 ubuntu "bash" 4 minutes ago Exited (0) About a minute ago nostalgic_volhard
66e80faf3913 hello-world "/hello" 7 minutes ago Exited (0) 7 minutes ago amazing_payne
You can see the containers you created with:
docker ps -l
Output
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
1233a80158d9 ubuntu "bash" 4 minutes ago Exited (0) 2 minutes ago nostalgic_volhard
Also, you can start an existing container with a container ID. For example:
docker start 1233a80158d9
Then you can use the docker ps command to see its status your output should similar to this:
Output
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
1233a80158d9 ubuntu "bash" 5 minutes ago Up 19 seconds nostalgic_volhard
To stop a running container, you can run the following command with container ID or name:
docker stop nostalgic_volhard
If you want to remove a container, you can run the following command with the name of that container. For example, to remove the hello-world, you run the following command:
docker rm amazing_payne
At this point, you learn how to manage Docker containers on Ubuntu 22.04 too.
Let’s see how Containers can be turned into images that you can use to build new containers.
Commit Changes in a Container to a Docker Image
In this part, you learn how to save the state of a container as a new Docker image.
After installing Node.js inside the Ubuntu container, you now have a container running off an image, but the container is different from the image you used to create it. But you might want to reuse this Node.js container as the basis for new images later.
Here you can commit the changes to a new Docker image with the following command:
docker commit -m "What you did to the image" -a "Author Name" container_id repository/new_image_name
For example for the user daniel, with the container ID of 1233a80158d9:
docker commit -m "added Node.js" -a "daniel" 1233a80158d9 daniel/ubuntu-nodejs
Then you can see your available images with the following command:
docker images
In your output you will see:
Output
REPOSITORY TAG IMAGE ID CREATED SIZE
daniel/ubuntu-nodejs latest 2d77de4a5b0a 12 seconds ago 199MB
ubuntu latest 2dc39ba059dc 3 weeks ago 77.8MB
hello-world latest feb5d9fea6a5 12 months ago 13.3kB
How to push Docker images to a Docker repository
After you create a new image from an existing image you may want to share it with a few of your friends, the whole world on Docker Hub, or other Docker registries that you have access to. To push an image to Docker Hub or any other Docker registry, you must have an account there.
To have an account on Docker hub you need to register at Docker Hub.
If you want to log in to the Docker hub you will be asked for authentication :
docker login -u docker-registry-username
If you enter the correct password, authentication should succeed. Then you may push your own image using the following command:
docker push docker-registry-username/docker-image-name
For example:
docker push daniel/ubuntu-nodejs
It will take a little time to complete. After you push an image to a registry, it should be listed on your account’s dashboard.
Note: If a push attempt results in an error of this sort, login, then repeat the push attempt.
Conclusion
At this point, you have learned to Install and Use Docker on Ubuntu 22.04.
Hope you enjoy it.
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