How to Install Docker on Ubuntu Linux

Docker provides an open-source containerization platform that packages applications and their dependencies into isolated containers, ensuring consistent performance across development, testing, and production environments. Unlike traditional virtual machines, Docker containers share the host OS kernel, making them lightweight and fast to start while maintaining strong isolation between applications.

This guide covers installing Docker on Ubuntu using the official Docker repository and APT package manager. You’ll learn repository setup, installation verification, systemd service management, and basic container operations to get started with Docker on your Ubuntu system.

System Requirements

Docker supports multiple Ubuntu versions across different architectures. Ensure your system meets the following requirements before proceeding with installation:

Ubuntu Version	Release Name	Supported Architectures
Ubuntu 25.10	Questing Quokka	x86_64/amd64, arm64, armhf
Ubuntu 25.04	Plucky Puffin	x86_64/amd64, arm64, armhf
Ubuntu 24.04 LTS	Noble Numbat	x86_64/amd64, arm64, armhf, s390x
Ubuntu 22.04 LTS	Jammy Jellyfish	x86_64/amd64, arm64, armhf, s390x

Docker requires a 64-bit version of Ubuntu with a kernel version of 3.10 or higher. LTS releases receive Docker support for their entire five-year support period, while non-LTS releases receive support for nine months following the Ubuntu release schedule.

Pre-installation Steps

If you use ufw or firewalld on Ubuntu, these firewalls do not forward traffic to and from Docker containers by default. This can cause connectivity issues when containers need to communicate with external networks or services. Docker modifies iptables rules directly, which may conflict with firewall configurations. Review your firewall rules and Docker networking requirements before proceeding if you rely on these tools for network security.

Before installing Docker on Ubuntu, check whether Docker is already installed on your system by running:

docker --version

If Docker is installed, this command displays the version number. If not, you’ll see a “command not found” message.

Before proceeding with installation, it’s important to remove any previous Docker installations to avoid conflicts. Additionally, these steps ensure a clean environment for your new Docker setup.

First, run the following command to eliminate these older versions:

sudo apt remove docker.io docker-compose docker-compose-v2 docker-doc podman-docker containerd runc

If you have not installed any of these packages, apt will send a message indicating nothing to remove.

The following commands will permanently delete all Docker images, containers, volumes, and networks stored in /var/lib/docker/ and /var/lib/containerd/. Only run these if you want a completely clean Docker installation.

Uninstalling Docker does not automatically remove images, containers, volumes, and networks stored in /var/lib/docker/. To start with a clean installation and delete all existing data, use the following commands:

sudo rm -rf /var/lib/docker
sudo rm -rf /var/lib/containerd

If you’re performing a complete uninstallation, remove the Docker repository keyring and source list to prevent package manager issues:

sudo rm /etc/apt/sources.list.d/docker.list
sudo rm /usr/share/keyrings/docker.gpg

After removing any older versions of Docker, you should update your system to ensure that all packages are up-to-date and avoid potential conflicts. You can do this by running the following command:

sudo apt update && sudo apt upgrade

This command updates the list of available packages and upgrades any ones that need updating.

Add Docker Repository to Ubuntu

Before installing Docker, import the Docker repository and GPG key into your system. This ensures that your system can verify the downloaded packages from the repository and prevent unauthorized changes.

To begin, install the required packages by running the following command:

sudo apt install ca-certificates curl gnupg lsb-release dirmngr software-properties-common apt-transport-https

This command installs the necessary packages for importing the Docker repository.

Next, import the GPG key using the curl command:

curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo gpg --dearmor -o /usr/share/keyrings/docker.gpg > /dev/null

This command downloads the GPG key from the Docker repository and saves it in the /usr/share/keyrings/ directory.

Finally, import the Docker repository by running the following command:

echo "deb [arch=$(dpkg --print-architecture) signed-by=/usr/share/keyrings/docker.gpg] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable" | sudo tee /etc/apt/sources.list.d/docker.list

This command adds the Docker repository to your system’s sources list and configures it to use the GPG key downloaded earlier.

After importing the repository, refresh your package index so APT reads metadata from download.docker.com:

sudo apt update

Once the cache is updated, verify that APT installs Docker from the official repository rather than the Ubuntu default repository:

apt-cache policy docker-ce

This displays the available Docker versions and their sources. The output should show the Docker repository URL (download.docker.com) with a higher priority than any Ubuntu repository entries, confirming your system will install from the correct source.

Example output:

docker-ce:
  Installed: (none)
  Candidate: 5:27.4.0-1~ubuntu.24.04~noble
  Version table:
     5:27.4.0-1~ubuntu.24.04~noble 500
        500 https://download.docker.com/linux/ubuntu noble/stable amd64 Packages

Install Docker on Ubuntu

Now you’re ready to install Docker on Ubuntu using the official Docker repository. This section covers the commands and steps required to install Docker efficiently and securely.

Update your system before installing Docker to ensure your source lists accurately reflect the newly imported repository. Run the following command to do this:

sudo apt update

Once your system is up-to-date, you can install Docker using the following command:

sudo apt install docker-ce docker-ce-cli containerd.io docker-buildx-plugin docker-compose-plugin

This command installs Docker and some additional plugins that you may find helpful.

After installing Docker, verify the installation by checking the service status and version:

sudo systemctl status docker

This displays detailed information about the Docker service, including whether it’s active and running. You should see output similar to:

● docker.service - Docker Application Container Engine
     Loaded: loaded (/lib/systemd/system/docker.service; enabled; vendor preset: enabled)
     Active: active (running) since Fri 2025-11-08 14:23:15 UTC; 2min ago
TriggeredBy: ● docker.socket
       Docs: https://docs.docker.com
   Main PID: 12345 (dockerd)
      Tasks: 8
     Memory: 42.1M
        CPU: 385ms
     CGroup: /system.slice/docker.service
             └─12345 /usr/bin/dockerd -H fd:// --containerd=/run/containerd/containerd.sock

The “active (running)” status confirms Docker is operating correctly. Additionally, verify the installed version:

docker --version

After installing Docker, verify the installation by running a test container. This helps confirm that Docker is set up correctly on your Ubuntu system.

Example of using hello-world on Docker with Ubuntu:

It’s important to note that the docker command requires root privileges to run. However, you can configure Docker to run as a non-root user, which provides a more secure way to manage containers and images.

If you experience any problems while working with Docker images going forward, try restarting your system, as sometimes this can fix issues related to path generation.

reboot

Managing Docker with systemd on Ubuntu

Systemd, a system and service manager, simplifies Ubuntu’s process and service management. Upon Docker installation on Ubuntu, it establishes a systemd unit to oversee the Docker service. Consequently, systemd commands can control this unit, offering a convenient method for starting, stopping, and managing Docker containers and images.

Below are some frequently used systemd commands for Docker management on Ubuntu:

sudo systemctl start docker.service

This starts the Docker service immediately for the current session. Use the enable command below if you want it to start automatically at boot.

sudo systemctl stop docker.service

This stops the Docker service until you start it again or reboot. It does not change whether Docker auto-starts on boot.

sudo systemctl restart docker.service

Restarts the Docker service.

sudo systemctl status docker.service

Displays the current status of the Docker service.

sudo systemctl enable docker.service

Enables the Docker service to start automatically on system boot. Docker installs with this enabled by default, but use this command if you previously disabled auto-start.

sudo systemctl disable docker.service

Disables automatic startup of the Docker service on system boot. The service remains available for manual start with systemctl start docker.service, but won’t launch during boot.

Docker Configuration and Usage

Manage Docker as a non-root user on Ubuntu

When running Docker, avoid using the root user to prevent security risks and accidental changes to the host system. Instead, manage Docker as a non-root user by adding users to the Docker group.

If you want to add a new user for Docker management, use the following command:

sudo useradd -m dockeruser

If the user already exists, skip this step.

Alternatively, to add an existing user (such as your current user) to the Docker group, use:

sudo usermod -aG docker username

The Docker group grants root-equivalent privileges to users. Members can access the Docker daemon socket, which provides full control over the host system. Only add trusted users to this group, as they can escape container isolation and modify host files. For production environments, consider using rootless Docker mode or implementing proper access controls.

Replace username above with the account you actually use on the Ubuntu system so you add the correct user to the Docker group.

After adding a user to the Docker group, you have two options to activate the group membership:

Option 1: Activate immediately without logging out using the newgrp command:

newgrp docker

This starts a new shell session with the docker group active, allowing you to run Docker commands immediately.

Option 2: Log out and back in, or reboot your system for the changes to take effect system-wide.

To ensure the user can run Docker commands, use the following command:

docker ps

This command displays a list of running containers, confirming the correct installation of Docker.

If you encounter permission errors when running Docker commands (such as errors accessing ~/.docker/config.json), fix the ownership and permissions on the Docker configuration directory:

sudo chown "$USER":"$USER" /home/"$USER"/.docker -R
sudo chmod -R g+rwx "$HOME/.docker"

These commands set the correct ownership and permissions for your user’s Docker configuration directory, resolving common permission-related issues.

Configure Default Logging Driver

By default, Docker logs to the JSON file format. However, you can configure the default logging driver to use a different format or send logs to a remote log management system.

Docker’s default json-file logging driver does not limit log file size or implement automatic rotation. Without proper configuration, containers can consume unlimited disk space through logging, potentially filling your filesystem. Always configure log rotation with max-size and max-file options in production environments to prevent disk exhaustion.

To change the default logging driver, create a new file called daemon.json in the /etc/docker/ directory using a text editor such as nano. For example, use the following command to create the file:

sudo nano /etc/docker/daemon.json

Once the file is open, you can add the following contents:

{
  "log-driver": "syslog",
  "log-opts": {
    "syslog-address": "tcp://logs.example.com:514",
    "syslog-facility": "daemon",
    "tag": "{{.Name}}"
  }
}

In this example, we configure Docker to use the syslog driver and to send logs to a remote syslog server. Replace “logs.example.com” with your syslog server’s address.

After creating the file, restart the Docker daemon to ensure that the changes made to the logging driver take effect:

sudo systemctl restart docker.service

It’s important to note that if you change the daemon.json file, you must restart the Docker daemon again to reload the changes.

Essential Docker Commands

When working with Docker, one must be familiar with the docker command used to manage Docker containers, images, networks, and volumes. Here are some of the most commonly used docker commands:

Command	Description
docker run	Run a new container from an image.
docker ps	List all running containers.
docker images	List all available images.
docker build	Build a new image from a Dockerfile.
docker stop	Stop a running container.
docker rm	Remove a container.
docker rmi	Remove an image.
docker network	Manage Docker networks.
docker volume	Manage Docker volumes.
docker info	Display system-wide Docker information.
docker search	Search Docker Hub for images.

docker info

The docker info command displays comprehensive system-wide information about your Docker installation, including the number of containers and images, storage driver details, and system resources.

docker info

This displays detailed information about your Docker environment, helping you verify configuration and troubleshoot issues. The output includes container and image counts, storage driver type, kernel version, and available plugins.

docker search

The docker search command searches Docker Hub for publicly available images matching your search term. This helps you discover official images and community-maintained alternatives before pulling them.

docker search ubuntu

This searches Docker Hub for images containing “ubuntu” in their name or description. The results include the image name, description, star count, and whether it’s an official image. Official images are maintained by Docker and the software vendor, providing higher reliability and security.

docker run

The docker run command runs a new container from an image. For example, to run a container from the ubuntu image:

docker run -it ubuntu:latest /bin/bash

This starts a new container from the ubuntu image and opens a shell inside the container.

docker ps

The docker ps command lists all running containers and provides information about each, including container ID, image name, and status.

docker ps

This displays a list of all running containers.

docker images

The docker images command lists all available images and supplies information about each image, including image ID, repository, and tag.

docker images

This displays a list of all available images.

docker build

The docker build command builds a new image from a Dockerfile, a script containing instructions for building an image.

docker build -t myimage:latest .

This builds a new image called myimage using the Dockerfile in the current directory.

docker stop

The docker stop command stops a running container. For example, to stop a container with the ID abcdefg:

docker stop abcdefg

This stops the container with the ID abcdefg.

docker rm

Use the docker rm command to remove a container. For example, to eliminate a container with the ID abcdefg:

docker rm abcdefg

This removes the container with the ID abcdefg.

docker rmi

The docker rmi command removes an image. For example, to eliminate an image with the ID 1234567:

docker rmi 1234567

This removes the image with the ID 1234567.

docker network

The docker network command manages Docker networks. It offers options to create, list, and remove networks.

docker network create mynetwork

This creates a new network called mynetwork.

docker volume

The docker volume command manages Docker volumes, providing options to create, list, and remove volumes.

docker volume create myvolume

This creates a new volume called myvolume.

Save Container Changes as Images

When working with Docker containers, changing the container you want to save as a new image is common. You can use the docker commit command to commit changes in a container to a Docker image.

First, start a new container from the base image and make any necessary changes to the container. For example, to start a new container from the ubuntu image and open a shell inside the container, you can use the following command:

docker run -it --name mycontainer ubuntu:latest /bin/bash

This command will start a new container from the ubuntu image and open a shell inside the container. You can make any necessary changes to the container, such as installing new software or modifying configuration files.

Once you have made the necessary changes, you can use the docker commit command to create a new image from the container. For example, to create a new image called myimage with the changes made in the mycontainer container, you can use the following command:

docker commit mycontainer myimage:latest

This command will create a new image called myimage with the changes made in the mycontainer container. You can now use this new image to create and run new containers with the updated software or configuration.

It’s important to note that the docker commit command only saves changes made to the container’s file system and does not save changes to the container’s networking or storage. If you need to save changes to these areas, use other Docker commands, such as docker network or docker volume.

Security Best Practices

Securing your Docker installation protects both containers and the host system from potential vulnerabilities. Follow these essential security practices when working with Docker on Ubuntu:

Run containers with least privilege: Avoid running containers as root when possible. Use the --user flag to specify a non-root user inside containers, limiting potential damage if a container is compromised.

Keep Docker updated: Regularly update Docker and the host system to receive security patches and bug fixes. Subscribe to Docker security advisories and apply updates promptly.

sudo apt update && sudo apt install --only-upgrade docker-ce docker-ce-cli containerd.io

This sequence refreshes the package lists and upgrades only the Docker components, leaving the rest of your system untouched.

Consider configuring unattended-upgrades to automatically apply security updates to Docker and the host system, ensuring your environment stays protected against known vulnerabilities.

Enable Docker Content Trust: Docker Content Trust uses digital signatures to verify the publisher and integrity of images. Enable it by setting the environment variable:

export DOCKER_CONTENT_TRUST=1

This ensures you only pull signed and verified images from trusted publishers.

Limit network exposure: Only expose necessary ports when running containers. Use specific port mappings instead of exposing all ports, and bind to localhost (127.0.0.1) instead of 0.0.0.0 when services don’t need external access. For remote management, use SSH tunneling to access container services securely.

docker run -p 127.0.0.1:8080:80 nginx

Scan images for vulnerabilities: Use Docker Scout or third-party tools to scan images for known security vulnerabilities before deploying them to production.

Implement resource limits: Prevent containers from consuming excessive system resources by setting memory and CPU limits using the --memory and --cpus flags.

Troubleshooting Common Issues

When working with Docker on Ubuntu, you may encounter common issues. This section covers the most frequent problems and their solutions.

Docker Daemon Not Starting

If the Docker daemon fails to start, check the service status first:

sudo systemctl status docker

If the service shows as failed or inactive, review the Docker logs for specific error messages:

sudo journalctl -u docker -n 50 --no-pager

This displays the last 50 log entries for the Docker service. Common causes include configuration syntax errors in /etc/docker/daemon.json, port conflicts, or insufficient system resources.

To resolve configuration issues, validate your daemon.json file syntax and restart the service:

sudo systemctl restart docker

If Docker still fails to start, ensure it’s enabled for automatic startup:

sudo systemctl enable docker

Permission Errors When Running Docker Commands

If you see “permission denied” errors when running Docker commands without sudo, verify your user is in the docker group:

groups

If “docker” doesn’t appear in the output, add your user to the group:

sudo usermod -aG docker $USER

Activate the group membership immediately using:

newgrp docker

Alternatively, log out and back in to apply the group changes system-wide.

If you encounter errors related to the Docker daemon socket (/var/run/docker.sock), check the socket permissions:

ls -l /var/run/docker.sock

The socket should be owned by root:docker with permissions srw-rw----. If permissions are incorrect, restart the Docker service to recreate the socket with proper permissions.

Container Networking Issues

If containers cannot reach external networks or other containers, verify Docker’s network configuration:

docker network ls

This lists all Docker networks. The default bridge network should appear. If you use ufw or firewalld, review the firewall warning in the Pre-installation Steps section, as these firewalls may block container traffic by default.

Test container networking by running a simple network test:

docker run --rm busybox ping -c 3 google.com

If this fails, check your host’s DNS configuration and ensure Docker can access /etc/resolv.conf.

Useful Links

Here are some valuable links related to using Docker:

• Docker Official Website: Visit the official website for information about the container platform, features, and download options.
• Docker Support: Access support resources for help with Docker, including documentation and community assistance.
• Docker Documentation: Explore comprehensive documentation for detailed guides on installing, configuring, and using Docker.
• Docker Training Resources: Access training resources and tutorials to learn how to use Docker effectively.

Conclusion

Docker delivers a powerful containerization platform for Ubuntu that streamlines application deployment and management across environments. The installation process covers repository setup, keyring configuration, package installation, systemd service management, and basic container operations. Your Ubuntu system now runs Docker with the tools to build, deploy, and manage containerized applications efficiently.