Free disk space by deleting "stale" docker images (keep around the latest N tags of each image)

delete_stale_images.sh

#!/bin/bash

images=$(./stale_image_tags.sh my.repo 3)

for image in $images; do
    docker rmi $image
done

stale_image_tags.sh

#!/bin/bash

if [ "$#" -ne 2 ]; then
    cat <<EOF
    Usage: stale_image_tags.sh <image prefix> <keep count>
        image prefix: e.g. my.repo
        keep count: how many most recent tags to excluse for each image

    Prints all image:tag pairs except the most recent <keep count> for each image.
EOF
    exit 1
fi
prefix=$1
keep_count=$(($2 + 1))

base_images=$(docker images | grep -e "^$prefix" | awk ' {print $1 }' | sort | uniq )

for image in $base_images; do
    docker images | grep $image | tail -n +$keep_count | awk '{print $1":"$2}'
done;