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Docker Setup

This guide will walk you through installing and configuring Docker for Ubuntu.

Pre-requisites

Docker Engine depends on containerd and runc. Docker Engine bundles these dependencies as one bundle: containerd.io. If you have installed the containerd or runc previously, uninstall them to avoid conflicts with the versions bundled with Docker Engine.

Run the following command to uninstall all conflicting packages:

sudo apt remove $(dpkg --get-selections docker.io docker-compose docker-compose-v2 docker-doc podman-docker containerd runc | cut -f1)

apt might report that you have none of these packages installed.

Install using the apt repository

Before you install Docker Engine for the first time on a new host machine, you need to set up the Docker apt repository. Afterward, you can install and update Docker from the repository.

  1. Set up Docker's apt repository. 

    # Add Docker's official GPG key:
sudo apt update
sudo apt install ca-certificates curl
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

# Add the repository to Apt sources:
sudo tee /etc/apt/sources.list.d/docker.sources <<EOF
Types: deb
URIs: https://download.docker.com/linux/ubuntu
Suites: $(. /etc/os-release && echo "${UBUNTU_CODENAME:-$VERSION_CODENAME}")
Components: stable
Signed-By: /etc/apt/keyrings/docker.asc
EOF

sudo apt update

  2. Install the Docker packages. 

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

    [!NOTE] Note The Docker service starts automatically after installation. To verify that Docker is running, use: 

    sudo systemctl status docker
    Some systems may have this behavior disabled and will require a manual start: 
    sudo systemctl start docker

  3. Verify that the installation is successful by running the hello-world image:

    sudo docker run hello-world

Troubleshooting

Permission Error

If you get a permission error, you may need to add your user to the Docker group.

  • Check socket ownership/permissions: 

    ls -l /var/run/docker.sock
# typical: srw-rw---- 1 root docker /var/run/docker.sock

  • If socket is owned by root:docker, add your user to the docker group (then restart shell or re-login):

    sudo usermod -aG docker $USER
# either log out/login or run:
newgrp docker

  • Retry bringing services up (same docker compose command): 

    docker compose up -d

Next Steps

Once Docker is setup the last step is to create your .env file.