How to Install and Use Docker on Ubuntu 22.04

December 12, 2023 December 12, 2023 12 min read

Accelerate your application development with Docker on Ubuntu Server. Docker is an open-source platform for building containerized applications and microservices. With Docker, every developer will have exactly the same environment. Also, you can easily share your application image with developers via the Docker Registry.

In this guide, we’ll take you through the installation of Docker on the Ubuntu system, and the basic usage of Docker for managing images, containers, volumes, and networking. With this, you can get started with ease.

Prerequisites

You will need the following to proceed:

An Ubuntu server 22.04 or later.
See also: 15 Steps to Install Ubuntu Server 22.04 LTS
A non-root user with sudo administrator privileges.

Installing Docker on Ubuntu

To get the latest version of Docker, you must install it from the official Docker repository. Complete the following steps to install Docker from the official Docker repository. Then, check if Docker is running and check the Docker version.

1. First, run the apt command below to install the package ca-certificates, curl, and gnupg to your system.

sudo apt install ca-certificates curl gnupg -y

2. Now execute the following command to add the GPG key of the Docker repository. The GPG key will be stored at /etc/apt/keyrings/docker.gpg.

# Creating directory /etc/apt/keyrings
sudo install -m 0755 -d /etc/apt/keyrings

## Adding Docker GPG Key
curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo gpg --dearmor -o /etc/apt/keyrings/docker.gpg

# Change permission of Docker GPG key
sudo chmod a+r /etc/apt/keyrings/docker.gpg

3. Then, run the command below to add the Docker repository to your Ubuntu system. In this case, you will add the Docker repository stable version.

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

Adding Docker repository and GPG key for Ubuntu Server

4. Once you’ve added the Docker repository, refresh your Ubuntu package index via apt update. Then, install Docker packages using the apt install command below.

# updating repository
sudo apt update

# Installing Docker CE
sudo apt install docker-ce docker-ce-cli containerd.io docker-buildx-plugin docker-compose-plugin

Type y to confirm and proceed with the installation.

Updating repository and installing Docker to Ubuntu

5. After that, execute the following systemctl command to ensure that Docker is running and enabled.

# checking if docker is enabled
sudo systemctl is-enabled docker

# checking docker status
sudo systemctl status docker

If the docker service is running, you should get the output active (running). The output enabled indicates that Docker will start automatically upon the system boot.

6. Lastly, run the docker command below to check the Docker version on your system.

docker version

The following output confirms that Docker 24.0.7 is installed.

Running Docker Without Sudo on Ubuntu

By default, only the root user can run containers with Docker. To allow non-root users to run containers with Docker, you must add your user to the docker group. This way you can run Docker containers without sudo.

1. First, execute the following command to add your user to the docker group.

sudo usermod -aG docker username

2. Then, log in to your user via the su command below.

su - username

3. Lastly, execute the following docker run command to run a new container hello-world.

docker run hello-world

If everything goes well, you should see the Hello World message from Docker.

Running Docker container as non-root user

Managing Docker Service on Ubuntu

The following steps are dedicated to managing the Docker service via the systemctl utility. This includes how to start and stop Docker in your Ubuntu machine, resting Docker service when needed, and checking the status of Docker service.

1. To start the docker service, use the systemctl start command below.

sudo systemctl start docker

2. Next, if you want to stop the docker service, use the following systemctl stop command.

sudo systemctl stop docker

3. When you make changes to Docker, you must restart the docker service to apply the changes. Execute the systemctl restart command below to restart it.

sudo systemctl restart docker

4. Lastly, to check the docker service status, use the systemctl status command below. If Docker is running, you should get an output such as active (running), otherwise, you can get an output such as failed.

sudo systemctl status docker

Working with Docker Images

At this point, Docker is running on your Ubuntu machine. Now you’ll learn how to manage Docker images using the docker utility. This includes searching images, downloading images, checking information about an image, and then removing Docker images from your Docker host.

1. First, find available Docker images with the name apache2 in the Docker Image Registry by executing the docker search command below.

docker search apache2

Finding Docker images via Docker Registry

2. Next, download the Docker image via the docker pull command below. In this case, you will download the image ubuntu/apache2.

docker pull ubuntu/apache2

The download process should look like this:

Downloading Docker image ubuntu/apache2 from Docker Registry

3. Once you’ve downloaded the image, run the following command to verify the list of downloaded images on your system.

docker images

If you followed this tutorial so far, you should two Docker images, ubuntu/apache2 and hello-world with the tag latest.

4. After that, check the detailed information about the image ubuntu/apache2:latest using the docker inspect command with option --type=image like the following.

docker inspect --type=image ubuntu/apache2:latest

The output should be formatted as json like the following:

Inspecting Docker image with JSON format

5. Furthermore, you can also check the information of the specific part from the Docker image by adding the parameter --format="{{.Section}}". For example, execute the command below to check the Config.Cmd and Size sections from the Docker image ubuntu/apache2:latest.

# checking the default CMD command
docker inspect --type=image --format="{{.Config.Cmd}}" ubuntu/apache2:latest

# checking size of image in bytes
docker inspect --type=image --format="{{.Size}}" ubuntu/apache2:latest

Checking the start command and size of Docker image

6. Lastly, run the docker rmi command below to delete the Docker image hello-world from your Ubuntu system.

sudo rmi hello-world

Managing Container

After downloading the Docker image, you’ll learn how to run the container, check if the container running, and inspect the container to get information about it, then you will also start and stop the container.

1. First, execute the docker run command below. After the command is executed, you should see the container ID.

docker run -d --name webserver1 -e TZ=UTC -p 8080:80 ubuntu/apache2:latest

Detailed options used in the command:

-d: Run the container in the background and imprint the container ID.
–name webserver1: give the new container name webserver1.
-e TZ=UTC: Set up environment variable TZ for the time zone within the container to UTC.
-p 8080:80: Expose the port 8080 on the Docker host machine, which is equivalent to port 80 on the container.

2. Now run the docker ps command below to verify the list of running containers.

docker ps

If everything goes well, you should see the container webserver1 with the status running and exposed port 8080 on the Docker host machine.

3. Then, run the docker inspect --type=container command below to get detailed information about the container webserver1. The output will be in json format, which contains detailed information about the webserver1 container.

docker inspect --type=container webserver1

4. Next, you can also specify the output of specific information via the --format="{{json .Section}}" parameter. For example, run the command below to check the status and pid (process id) of the webserver1 container.

# checking the state/status and PID of webserver1
docker inspect --type=container --format="{{json .State.Status}}" webserver1
docker inspect --type=container --format="{{json .State.Pid}}" webserver1

5. Furthermore, run the following command to get the internal IP address from the section .NetworkSettings.IPAddress and the exposed port from the section .NetworkSettings.Ports on the webserver1 container.

# checking the IP address and ports of webserver1
docker inspect --type=container --format="{{json .NetworkSettings.IPAddress}}" webserver1
docker inspect --type=container --format="{{json .NetworkSettings.Ports}}" webserver1

Inspecting container status, pid, IP address, and ports

6. Next, stop the container webserver1 using the docker stop command below. Then verify again the list containers via the docker ps -a command. The -a parameter will show you containers that are running and exited.

# stopping container webserver1
docker stop webserver1
docker ps -a

You should see the webserver1 container is exited.

7. Then, if you want to start the container webserver1 again, simply run the docker start command below.

docker start webserver1

8. Lastly, run the docker rm command below to remove the container webserver1. The parameter -f is used to force the removal of the container.

docker rm webserver1 -f

Managing Volumes

Volumes are where you can store data of your application persistently in Docker. In the following step, you’ll learn how to create, manage, and use Docker volume on your container.

1. First, create a new directory ~/local-data and the custom index.html page via vim editor.

mkdir -p ~/local-data
vim ~/local-data/index.html

Insert the following HTML script into the file.

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <title>Welcome to Apache2 Docker</title>
</head>
<body>
  <h2>Hello from webserver2 container - Powered by Apache2</h2>
</body>
</html>

When finished, save and exit the file.

2. Then, execute the docker run command below to create a new container webserver2.

docker run -d --name webserver2 -e TZ=UTC -v ~/local-data:/var/www/html -p 8082:80 ubuntu/apache2:latest

-v ~/local-data:/var/www/html: The -v option is used to mount the volume of the local directory ~/local-data to the target directory /var/www/html on the container.

3. Next, verify the list running container using the docker ps command below. You should see the webserver2 container with the status UP and exposed port 8082 on the Docker host machine.

docker ps

4. After that, run the docker inspect command below to check the Binds and Mounts within the webserver2 container.

# checking bind volume of webserver2
docker inspect --format="{{json .HostConfig.Binds}}" webserver2

# checking mounts of volume in webserver2
docker inspect --format="{{json .Mounts}}" webserver2

You should get an output that the local directory ~/local-data is mounted to the target directory /var/www/html on the container.

Checking the mount directory of Docker container

5. Lastly, launch your web browser and visit the server IP address followed by port 8082, i.e: http://192.168.5.30:8082/. If everything goes well, you should see the custom index.html page that you’ve created on the ~/local-data directory.

Managing Networks

The Docker container is running in an isolated environment and uses its networking configuration. each container has an internal IP address, which is provided by the Docker network. Complete the following section to learn how to create, manage, and use the Docker network.

1. To start, execute the docker network create command below to create a new network on Docker. In this case, you will create a new network mynet with the default configuration for both driver and subnet.

docker network create mynet

2. After you’ve created mynet network, execute the docker network ls command below to verify the list of networks on Docker. You should see network mynet is created.

docker network ls

3. Also, you can check the specific configuration of the mynet network via the docker inspect --type=network command below.

# checking default driver of Docker network mynet
docker inspect --type=network --format="{{json .Driver}}" mynet

# checking IP address configuration of mynet network
docker inspect --type=network --format="{{json .IPAM.Config}}" mynet

You should see the mynet network is using the default driver bridge and subnet 172.18.0.0/16.

Checking driver and subnet of Docker network

4. Next, use the docker run command below with the parameter --network to attach a specific network for your container. In this case, you will create a new container webserver3 with the network mynet.

docker run -d --name webserver3 --network mynet -e TZ=UTC -p 8083:80 ubuntu/apache2:latest

5. Once the webserver3 container is running, install the jq package via the apt install command below. The jq package is a json parser program that makes json output colorful and pretty.

sudo apt install jq -y

6. Lastly, run the docker inspect --type=container command below to check the network configuration for the webserver3 container.

docker inspect --type=container --format="{{json .NetworkSettings.Networks}}" webserver3 | jq

The following output confirm that the webserver3 container uses mynet as the default networking configuration with IP address 172.18.0.2.

Checking container network configuration

Checking Container Logs for Troubleshooting

In the following step, you will learn how to check the logs of your containers via the docker client.

1. To check the logs of the container, run the docker logs command below. This will show you all logs since the container is created to present.

docker logs webserver3

2. Next, add the option --follow to show container logs in streaming mode.

docker logs --follow webserver3

3. Then, you can also check the last N lines of container logs via the --tail parameter like this. In this case, you will check logs for the last 10 lines.

docker logs --tail 10 webserver3

4. Furthermore, you can also show logs of containers since timestamps via the --since parameter.

docker logs --since 20m webserver3

5. Lastly, use the --until parameter to sho logs before timestamps.

docker logs --until 10m webserver3

Conclusion

To wrap up, you’ve completed the installation of Docker on the Ubuntu Server. You’ve also learned how to manage images, containers, volumes, and networking in Docker. You can now start containerizing your application via Docker.

Further reading, go over the containerizing of language-specific applications, such as Node.js, Python, Golang, and Java.

ArvidL

System administrator and devops enthusiast, leveraging over 10+ years of Linux expertise to optimize operations. Proficient in FreeBSD, VMWare, KVM, Proxmox, PfSense, Ansible, Docker, and Kubernetes.