FunOS

Docker is a powerful tool for creating, deploying, and running applications using containers. In this guide, we will walk you through the installation of Docker Engine on FunOS, a lightweight Linux distro based on Ubuntu.

Install Docker Engine

1. Uninstall Old Versions of Docker

If you have previously installed Docker or any other container management tools, it’s important to remove them before installing Docker Engine to avoid conflicts. Run the following command to remove older versions:

for pkg in docker.io docker-doc docker-compose docker-compose-v2 podman-docker containerd runc; do sudo apt remove $pkg; done

This command ensures that any previous Docker-related packages are cleanly uninstalled from your system.

2. Set Up Docker’s Apt Repository

Docker packages are available through Docker’s official repositories. Before installing, you need to configure these repositories.

Step 1: Install Required Dependencies

Update your system and install the ca-certificates and curl packages, which are necessary for downloading and setting up the Docker repository.

sudo apt update
sudo apt install ca-certificates curl

Step 2: Add Docker’s Official GPG Key

Next, you need to add Docker’s GPG key to verify the integrity of the packages:

sudo install -m 0755 -d /etc/apt/keyrings
sudo curl -fsSL https://download.docker.com/linux/ubuntu/gpg -o /etc/apt/keyrings/docker.asc
sudo chmod a+r /etc/apt/keyrings/docker.asc

Step 3: Add Docker Repository to Apt Sources

Now that the GPG key is in place, add Docker’s apt repository to your system’s sources list:

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

Step 4: Update Package Index

Update your package index to include Docker’s repository:

sudo apt update

3. Install Docker Packages

With the repository added and updated, you can now proceed to install Docker Engine and other related packages:

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

These packages include:

• docker-ce: The Docker Engine itself.
• docker-ce-cli: Docker command-line interface.
• containerd.io: The container runtime.
• docker-buildx-plugin: The buildx tool for building multi-platform images.
• docker-compose-plugin: For managing multi-container applications.

4. Verify Docker Installation

Once the installation is complete, you can verify that Docker Engine is working correctly by running the hello-world container:

sudo docker run hello-world

This command pulls and runs a small container that outputs a message confirming that Docker is installed and running properly.

5. Manage Docker as a Non-Root User

By default, Docker requires root privileges to run commands. However, you can configure Docker to be used by a non-root user to avoid needing sudo every time.

Step 1: Create the Docker Group

Create a new group called docker:

sudo groupadd docker

Step 2: Add Your User to the Docker Group

Add your user to the docker group:

sudo usermod -aG docker $USER

Step 3: Log Out and Log Back In

To apply the group changes, log out of your session and log back in. Alternatively, you can activate the changes without logging out by running the following command:

newgrp docker

Step 4: Verify Docker Without Sudo

You can now check if Docker runs without needing sudo by running the following command:

docker run hello-world

If everything is set up correctly, you should see the same output as in step 4, but without having to prepend sudo to the command.

Uninstall Docker Engine

If you want to remove Docker Engine and related packages from your system, follow these steps.

1. Uninstall the Docker Engine, CLI, containerd, and Docker Compose packages

sudo apt purge docker-ce docker-ce-cli containerd.io docker-buildx-plugin docker-compose-plugin docker-ce-rootless-extras

This will remove Docker but keep your Docker images, containers, and volumes intact.

2. Remove the repository and key (optional)

sudo rm -f /etc/apt/sources.list.d/docker.list 
sudo rm -f /etc/apt/keyrings/docker.asc
sudo apt update

This will remove the Docker repository and Docker’s GPG key.

3. Remove Docker Data (optional)

If you want to completely remove all Docker images, containers, volumes, and configuration files, run the following commands:

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

Conclusion

Docker Engine is now successfully installed on FunOS, and you’re ready to start building and deploying containerized applications. By following the steps above, you can manage Docker efficiently without root privileges. Happy containerizing!