Extract a container image and run the container against the underlying directory

container_basedir.sh

#!/bin/sh

set -e

container_name="centos:8"
clean_container_name=$( echo "${container_name}" | tr ':' '_' )
export_file="${clean_container_name}.tar"

if [ -f "${export_file}" ]; then
  echo "Found ${export_file}; remove the file to re-extract"
else
  id=$( podman run -id $container_name )
  podman export $id > "${export_file}"
  podman rm -f $id
fi

export_file=$( readlink -f "${export_file}" )

target_dirs=( $(tar -tf "${export_file}" | grep '^[[:alnum:]]\+/$' | tr -d '/') )
dirs_to_remove="dev tmp run proc sys lost+found media mnt"

for dir in ${dirs_to_remove[@]}; do
  target_dirs=( "${target_dirs[@]/$dir}" )
done

container_volumes=()
for dir in ${target_dirs[@]}; do
  volume_name="${clean_container_name}_${dir}"

  set +e
  volume_info=$( podman volume inspect "${volume_name}" 2>/dev/null )

  if [ $? -ne 0 ]; then
    set -e
    podman volume create "${volume_name}" >& /dev/null
    volume_info=$( podman volume inspect "${volume_name}" )
  fi

  set -e

  container_volumes+=("-v ${volume_name}:/${dir}:Z")

  (
    cd $( echo "${volume_info}" | jq -r '.[] | .Mountpoint' )
    tar --skip-old-files --strip-components=1 -xf "${export_file}" "${dir}/"
  )
done

echo "${container_name} volumes extracted and ready"
echo "Run the following command to execute:"
echo "podman run $( IFS=$' '; echo "${container_volumes[*]}" ) --systemd=always -id $container_name /usr/sbin/init"