How to Completely Uninstall Docker

In this tutorial, we will show you how to Completely Uninstall Docker. Docker has revolutionized application deployment through containerization, making it easier to package and distribute software. However, there are times when you need to completely remove Docker from your system. Whether you’re troubleshooting issues, reclaiming disk space, or transitioning to alternative solutions, this guide will walk you through the process of properly uninstalling Docker across various Linux distributions. We’ll cover everything from understanding Docker’s architecture to post-uninstallation verification, ensuring you can confidently remove Docker without leaving behind unwanted remnants.

Understanding Docker Architecture

Before jumping into the uninstallation process, it’s important to understand what Docker components exist on your system. Docker isn’t just a single application but rather a collection of interconnected components.

Docker consists of several key elements that work together to enable containerization:

• Docker Engine: The core runtime that builds and runs containers
• Docker CLI: The command-line interface for interacting with Docker
• Docker Daemon: The background service that manages Docker objects
• Docker Registry: Stores Docker images
• Docker Objects: Includes images, containers, networks, and volumes

These components are spread across various directories and files in your Linux system. The main locations include:

• /var/lib/docker: Stores images, containers, volumes, and other Docker data
• /etc/docker: Contains Docker configuration files
• /usr/bin/docker: The Docker binary
• /var/run/docker.sock: The Docker socket file

Understanding this architecture helps ensure you completely remove all Docker components without leaving residual files that might cause conflicts later.

When to Uninstall Docker

There are several legitimate reasons why you might need to completely uninstall Docker from your system:

Fixing Installation Issues: Sometimes Docker installations become corrupt, causing unpredictable behavior or non-functioning features. A complete reinstallation can resolve these issues.

System Cleanup: Docker can consume significant disk space over time, especially if you’ve been using it extensively. Uninstalling Docker can help reclaim valuable storage resources.

Performance Optimization: In some cases, Docker containers might overconsume system resources, affecting overall performance. Removing Docker temporarily can help identify if it’s the source of performance issues.

Reset Configuration: If you’ve made numerous configuration changes and want to start fresh, uninstalling and reinstalling Docker lets you return to default settings.

Transitioning to Alternatives: You might be moving to alternative containerization solutions like Podman or LXC/LXD.

Security Concerns: If you’ve identified security vulnerabilities in your current Docker installation, a complete uninstallation and fresh installation of the latest version can resolve potential security issues.

Pre-Uninstallation Preparations

Before you begin the uninstallation process, it’s crucial to properly prepare your system to avoid data loss and ensure a smooth removal process.

Backing Up Critical Data

First, identify which Docker containers and volumes contain important data. If you plan to reinstall Docker later, you’ll want to preserve this information. Here’s how to back up your critical Docker data:

1. List all running containers:

sudo docker ps -a

2. Export important container data:

sudo docker export [container_id] > container_backup.tar

3. Back up Docker volumes:

sudo docker volume ls
sudo docker volume inspect [volume_name]

Save any important volume data using appropriate backup methods before proceeding.

Container Management Before Removal

Properly stopping and removing containers is essential before uninstalling Docker:

1. Stop all running containers:

sudo docker stop $(sudo docker ps -q)

2. Force remove all containers:

sudo docker rm -f $(docker ps -aq)

3. Clean up Docker system resources:

sudo docker system prune --volumes

4. Verify all containers are removed:

sudo docker ps -a

This output should be empty, indicating all containers have been successfully removed.

Step-by-Step Uninstallation Process for Ubuntu

Now that you’ve backed up your data and stopped all containers, let’s proceed with the complete uninstallation process for Ubuntu.

Stopping Docker Services

Before removing Docker packages, ensure all Docker services are completely stopped:

1. Stop the Docker daemon:

sudo systemctl stop docker

2. Stop containerd service if running:

sudo systemctl stop containerd

3. Verify Docker is not running in the background:

ps aux | grep docker

Removing Docker Packages

Next, remove all Docker-related packages from your system:

1. Remove Docker packages:

sudo apt-get remove 'docker*'

2. Purge Docker packages to remove configuration files:

sudo apt-get purge 'docker*'

3. Remove Docker Engine, CLI, and containerd packages:

sudo apt-get purge -y docker-engine docker docker.io docker-ce docker-ce-cli

4. Use autoremove to clean up any remaining dependencies:

sudo apt-get autoremove -y --purge docker-engine docker docker.io docker-ce docker-ce-cli

This comprehensive approach ensures all Docker packages are completely removed from your system.

Cleaning Docker Configuration Files

After removing the packages, you need to delete Docker configuration files:

1. Remove the Docker configuration directory:

sudo rm -rf /etc/docker

2. Delete Docker daemon configuration file:

sudo rm -f /etc/systemd/system/docker.service

3. Remove Docker socket configuration:

sudo rm -f /etc/systemd/system/docker.socket

Removing Docker Data Directories

Docker stores most of its data in specific directories that need to be removed for a complete uninstallation.

1. Delete the main Docker data directory:

sudo rm -rf /var/lib/docker

2. Remove Docker runtime files:

sudo rm -rf /var/run/docker

3. Delete Docker socket file:

sudo rm -rf /var/run/docker.sock

4. Remove containerd data directory:

sudo rm -rf /var/lib/containerd

These commands remove all Docker-related data directories, which is essential for ensuring no remnants of Docker remain on your system.

Removing User Settings and Permissions

Docker creates user groups and permissions that should be removed as part of a complete uninstallation.

1. Remove the Docker group:

sudo groupdel docker

2. Check for users with Docker permissions:

grep docker /etc/group

3. Clean up Docker-related environment variables:

unset DOCKER_HOST DOCKER_TLS_VERIFY DOCKER_CERT_PATH

4. Remove Docker Compose configurations if installed:

sudo rm -f /usr/local/bin/docker-compose

These steps ensure that all user-specific Docker settings and permissions are completely removed from your system.

Cleaning Dependencies and Associated Components

To complete the uninstallation process, clean up any remaining dependencies and associated components.

1. Use apt autoremove to clean unused dependencies:

sudo apt-get autoremove -y

2. Remove Docker GPG keys:

sudo rm /etc/apt/keyrings/docker.asc

3. Delete Docker repository entries:

sudo rm /etc/apt/sources.list.d/docker.list

4. Update package list after removal:

sudo apt-get update

5. Find and remove any remaining Docker files:

sudo find / -name "*docker*" -exec rm -rf {} \;

This thorough cleanup ensures that all Docker-related components, including dependencies and repository configurations, are completely removed from your system.

Verifying Complete Uninstallation

After completing the uninstallation steps, it’s important to verify that Docker has been completely removed from your system.

1. Check for Docker processes:

ps aux | grep docker

2. Verify Docker packages are removed:

dpkg -l | grep -E 'docker'

3. Test Docker command functionality:

docker --version

This should return “command not found” if Docker is completely uninstalled.

4. Verify Docker service is removed:

sudo systemctl status docker

You should see “Unit docker.service could not be found” as output.

5. Check for Docker socket:

ls -la /var/run/docker.sock

If any of these checks indicate that Docker components are still present, you may need to perform additional cleanup steps.

Uninstalling Docker on Other Linux Distributions

While the focus of this guide has been Ubuntu, the process for uninstalling Docker on other Linux distributions follows similar principles with some distribution-specific commands.

CentOS/RHEL

For CentOS and RHEL systems, use the following commands:

1. Stop Docker services:

sudo systemctl stop docker

2. Remove Docker packages:

sudo yum remove docker docker-common docker-selinux docker-engine

3. Delete Docker data directories:

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

Fedora

For Fedora systems:

1. Stop Docker services:

sudo systemctl stop docker

2. Remove Docker packages:

sudo dnf remove docker-ce docker-ce-cli containerd.io

3. Delete Docker data directories:

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

Arch Linux

For Arch Linux and its derivatives:

1. Stop Docker services:

sudo systemctl stop docker

2. Remove Docker packages:

sudo pacman -R docker

3. Delete Docker data directories:

sudo rm -rf /var/lib/docker

Troubleshooting Common Uninstallation Issues

Even with careful planning, you might encounter some issues during the Docker uninstallation process. Here are solutions to common problems:

“Cannot Remove” Errors

If you encounter “cannot remove” errors:

1. Make sure all containers are stopped:

sudo docker stop $(sudo docker ps -aq)

2. Check for running Docker processes and kill them:

ps aux | grep docker
sudo kill -9 [PID]

3. Try forcing the removal:

sudo apt-get purge --force-yes docker-ce docker-ce-cli

Locked Files During Removal

If files are locked during removal:

1. Reboot your system and try again:

sudo reboot

2. After reboot, proceed with the uninstallation process.

Persistent Docker Processes

If Docker processes persist after uninstallation:

1. Check for zombie processes:

ps aux | grep docker | grep defunct

2. Reboot the system to clear any zombie processes:

sudo reboot

Permission Issues During Cleanup

If you encounter permission issues:

1. Ensure you’re using sudo with the commands.

2. Check file permissions:

ls -la /var/lib/docker

3. Use the force flag with rm commands if necessary:

sudo rm -rf --no-preserve-root /var/lib/docker

Reinstalling Docker After Complete Removal

If you plan to reinstall Docker after uninstallation, follow these best practices for a clean installation:

1. Update your package index:

sudo apt-get update

2. Install prerequisites:

sudo apt-get install apt-transport-https ca-certificates curl software-properties-common

3. Add Docker’s official GPG key:

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

4. Set up the Docker repository:

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

5. Update the package index again:

sudo apt-get update

6. Install Docker:

sudo apt-get install docker-ce docker-ce-cli containerd.io

7. Verify the installation:

sudo docker run hello-world

This process ensures a clean, fresh installation of Docker that avoids any issues from previous installations.