Bash script that loops over Docker images, and keeps only the latest tag for each image name (Repository).

delete-older-docker-image-tags.sh

#!/bin/bash

set -e

echo "Script for cleaning up Docker images"

# First, we grab a list of all images
docker_images=$(docker images --format "{{.ID}}|{{.Repository}}|{{.Tag}}")

# prepare a image name lookup
declare -A image_names

# Then, we loop through the list
while read -r line; do
    # We split the line into an array
    IFS='|' read -r -a array <<< "$line"

    # We grab the image ID
    image_id=${array[0]}

    # We grab the image name
    image_name=${array[1]}

    # We grab the image tag
    image_tag=${array[2]}

    # We check if the image_name has already been saved in image_names
    if [[ -z "${image_names[$image_name]}" ]]; then
        # If not, we save it
        echo "Keeping ${image_name}:${image_tag}"
        image_names[$image_name]=$image_id
    else
        # If yes, we remove the image
        echo "Removing ${image_name}:${image_tag}"
        docker rmi "${image_name}:${image_tag}"
    fi
done <<< "$docker_images"

zsh-delete-older-docker-image-tags.sh

#!/bin/zsh
# Next time this breaks, port it to python!

echo "Script for cleaning up Docker images"
echo "===================================="
echo ""

# Run prune before deleting tags to clean up problematic <none> tags
echo "Pruning images"
echo "--------------"
docker system prune -f
echo ""


echo "Remove older tags for images"
echo "----------------------------"
# First, we grab a list of all images
docker_images=$(docker images --format "{{.ID}}|{{.Repository}}|{{.Tag}}")

# prepare a image lookups
declare -A image_ids
declare -A image_tags

# Then, we loop through the list
while read -r line; do
    # We split the line into an array
    IFS='|' read -r -A array <<< "$line"

    # We grab the image ID
    image_id=${array[1]}

    # We grab the image name
    image_name=${array[2]}

    # We grab the image tag
    image_tag=${array[3]}

    # We check if the image_name has already been saved in image_ids
    if [[ -z "${image_ids[$image_name]}" ]]; then
        # If not, we save it
        echo "Keeping ${image_name}:${image_tag}"
        image_ids[$image_name]=$image_id
        image_tags[$image_name]=$image_tag
    # If yes, we check if image_id matches and image_tag is older
    elif [[ "${image_ids[$image_name]}" == "$image_id" ]] && [[ "${image_tags[$image_name]}" < "$image_tag" ]]; then
        # If yes, we delete the saved image
        echo "Found newer tag for ${image_name}:${image_tag}"
        echo "Deleting ${image_name}:${image_tags[$image_name]}"
        docker rmi "${image_name}:${image_tags[$image_name]}" || true  # ignore errors (e.g. if image is in use)
        # And we save the new image
        image_tags[$image_name]=$image_tag
    else
        # If yes, we remove the image
        echo "Deleting ${image_name}:${image_tag}"
        docker rmi "${image_name}:${image_tag}" || true  # ignore errors (e.g. if image is in use)
    fi
done <<< "$docker_images"
echo ""

# Run prune after deleting tags to clean up layers and cache
echo "Pruning images (again)"
echo "----------------------"
docker system prune -f
echo ""