docker-cleanup

#!/bin/bash

help() {
   echo 'usage: docker-cleanup'
   echo '       docker-cleanup --help'
   echo
   echo '    Will remove:'
   echo '      - stopped containers'
   echo '      - dangling volumes'
   echo '      - unused networks'
   echo '      - images without repository and without tag (<none> <none>)'
   echo '      - older versions of images with identical repository and tag'
   echo '      - dangling images'
   echo
   exit 1
}

[ "$1" == "--help" ] && help

set -e          # stop on error
set -u          # stop on undefined variable
set -o pipefail # stop part of pipeline failing

docker system prune --volumes

previous_repository=""
previous_tag=""
previous_id=""
# images are sorted older to younger
#
docker images --format "{{.Repository}} {{.Tag}} {{.CreatedAt}} {{.ID}}" \
| sort \
| while read repository tag created_at id; do
    if   [ "$tag" == "<none>" ]        && [ "$repository" == "<none>" ];          then
        echo docker rmi $id
    elif [ "$tag" == "$previous_tag" ] && [ "$repository" == "$previous_repository" ]; then
        echo docker rmi $previous_id
    fi
    previous_repository=$repository
    previous_tag=$tag
    previous_id=$id
done

# in case iterating through images above left some
# dangling ones, then delete then now
docker image prune --filter=dangling=true