Bash script to install Docker in WSL2 without using Docker Desktop. Tested with Debian 11.3 and Ubuntu 20.04 LTS. Based on information from the Docker installation instructions and https://dev.to/felipecrs/simply-run-docker-on-wsl2-3o8

install-docker-wsl2.sh

#!/bin/bash

set -e

if [ "$USER" = "root" ]; then
    echo "This script shouldn't run as root (don't use sudo)."
    exit 1
fi

echo "Elevating..."
sudo echo " - ok!"

# Uninstall older versions
echo
echo "Uninstalling older versions..."

if [ $(dpkg-query -W -f='${Status}' docker | grep -c "ok installed") -ne 0 ]; then
    echo " - removing docker..."
    sudo apt-get remove docker -y >/dev/null
fi

if [ $(dpkg-query -W -f='${Status}' docker-engine | grep -c "ok installed") -ne 0 ]; then
    echo " - removing docker-engine..."
    sudo apt-get remove docker-engine -y >/dev/null
fi

if [ $(dpkg-query -W -f='${Status}' docker.io | grep -c "ok installed") -ne 0 ]; then
    echo " - removing docker.io..."
    sudo apt-get remove docker.io -y >/dev/null
fi

if [ $(dpkg-query -W -f='${Status}' containerd | grep -c "ok installed") -ne 0 ]; then
    echo " - removing containerd..."
    sudo apt-get remove containerd -y >/dev/null
fi

if [ $(dpkg-query -W -f='${Status}' runc | grep -c "ok installed") -ne 0 ]; then
    echo " - removing runc..."
    sudo apt-get remove runc -y >/dev/null
fi

if [ -f "/etc/apt/sources.list.d/docker.list" ]; then
    echo " - removing apt source file: /etc/apt/sources.list.d/docker.list"
    sudo rm /etc/apt/sources.list.d/docker.list
fi


# Set up the docker repo
echo
echo "Setting up the Docker repository..."
echo " - installing prerequisites..."
sudo apt-get update >/dev/null

echo "   - installing ca-certificates..."
sudo apt-get install ca-certificates -y >/dev/null

echo "   - installing curl..."
sudo apt-get install curl -y >/dev/null

echo "   - installing gnupg..."
sudo apt-get install gnupg -y >/dev/null

echo "   - installing lsb-release..."
sudo apt-get install lsb-release -y >/dev/null

echo " - loading Docker GPG key..."
sudo mkdir -p /etc/apt/keyrings
if [ -f "/etc/apt/keyrings/docker.gpg" ]; then
    sudo rm /etc/apt/keyrings/docker.gpg
fi
curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo gpg --dearmor -o /etc/apt/keyrings/docker.gpg

echo " - creating Docker apt source file: /etc/apt/sources.list.d/docker.list"
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


# Install docker
echo
echo "Installing Docker..."
sudo apt-get update >/dev/null

echo " - installing docker-ce..."
sudo apt-get install docker-ce -y >/dev/null

echo " - installing docker-ce-cli..."
sudo apt-get install docker-ce-cli -y >/dev/null

echo " - installing containerd.io..."
sudo apt-get install containerd.io -y >/dev/null

echo " - installing docker-compose-plugin..."
sudo apt-get install docker-compose-plugin -y >/dev/null

if ! (ls -l /etc/alternatives/iptables | grep -qe "/iptables-legacy$"); then
    echo " - switching to iptables-legacy..."
    sudo update-alternatives --set iptables /usr/sbin/iptables-legacy >/dev/null
fi


echo
echo "Finishing up..."

# Add user to docker group
if ! (groups | grep -q "docker"); then
    echo " - adding user '$USER' to the docker group..."
    sudo usermod -aG docker $USER
fi

# Auto-start docker service
if ! (grep -q "# Start Docker service" ~/.profile); then
    echo " - adding docker auto-start entry to ~/.profile..."

    (cat << EOF


# Start Docker service
if service docker status 2>&1 | grep -q "is not running"; then
    echo "Starting Docker service..."
    wsl.exe -d "\${WSL_DISTRO_NAME}" -u root -e /usr/sbin/service docker start >/dev/null 2>&1
fi
EOF
    ) >> ~/.profile
fi

echo
echo "All set!  Open a new session and type 'docker version' to confirm everything is working."