Install docker on Debian. Further, create the docker group and add the current user to it. Finally, set a custom location for storing images.

install-docker-debian.sh

#! /usr/bin/env bash

image_loc="/data/docker"

###
# https://docs.docker.com/engine/install/debian/
###

# set up the docker repository

sudo apt update
sudo apt -y install \
    apt-transport-https \
    ca-certificates \
    curl \
    gnupg \
    lsb-release
	
curl -fsSL https://download.docker.com/linux/debian/gpg | sudo gpg --dearmor -o /usr/share/keyrings/docker-archive-keyring.gpg

echo \
  "deb [arch=amd64 signed-by=/usr/share/keyrings/docker-archive-keyring.gpg] https://download.docker.com/linux/debian \
  $(lsb_release -cs) stable" | sudo tee /etc/apt/sources.list.d/docker.list > /dev/null
  
 # install docker
sudo apt update
sudo apt install docker-ce docker-ce-cli containerd.io

# test installation
sudo docker run hello-world

###
# https://docs.docker.com/engine/install/linux-postinstall/
###

# create the docker group if it does not already exist
# it is fine if the group already exists
sudo groupadd docker || true

# add users
sudo usermod -aG docker $USER

# update groups
newgrp docker

###
# It is necessary to restart the service for the new permissions
# and such to work.
#
# See: https://github.com/jgsqware/clairctl/issues/60#issuecomment-402564931
###

sudo service docker restart

###
# Change the location of docker images
#
# https://www.ibm.com/docs/ja/cloud-private/3.1.0?topic=pyci-specifying-default-docker-storage-directory-by-using-bind-mount
###
docker rm -f $(docker ps -aq)
docker rmi -f $(docker images -q)

sudo service docker stop
sudo rm -rf /var/lib/docker
sudo mkdir /var/lib/docker

sudo mkdir $image_loc
sudo chown $USER: $image_loc
sudo mount --rbind $image_loc /var/lib/docker

#sudo systemctl start docker
sudo service docker start

###
# For the binding to come back after rebooting, it is necessary to update /etc/fstab.
###

In practice, it seems that using symlinks are an easier option compared to using bind mounts for using different locations.