delete_registry_digests.sh

#!/bin/bash
# This script removes tags from local registry, keeping just the n most recents tags
# after this script run, run the following script to free the space:
#   bin/registry garbage-collect /etc/docker/registry/config.yml
#
# Examples (dryrun and execution):
#   ./delete_registry_digests.sh -r http://registry.local:5000 -i test -k 0
#   ./delete_registry_digests.sh -r https://registry.example.com -i dev/test -e latest -d
#
# After deleting all the tags, run garbage collection:
#   registry garbage-collect -m /etc/docker/registry/config.yml
#
# based on: https://gist.github.com/jaytaylor/86d5efaddda926a25fa68c263830dac1?permalink_comment_id=4732942#gistcomment-4732942
# and on: https://stackoverflow.com/questions/31251356/how-to-get-a-list-of-images-on-docker-registry-v2
# Abels changes:
# - Not using jq utility, just curl and native linux binaries
# - Check based tag count, removing last n versions
# Sean's changes:
# - Add timestamp option - only delete tags earlier than the timestamp
# - Add delete option - default to dryrun
# - Add help option

# Function to check if has more than n tags and remove
check_tags_more_than_n_versions() {
    # Get tag list, not sorted
    local tagurl="${registry}/v2/${image}/tags/list"
    echo "Registry  : ${registry}"
    echo "Image name: ${image}"
    echo
    local tags=$(curl -k -s -u $user:$password "$tagurl" | awk -F: '{print $3}' | sed -e 's/[][]//g' -e 's/\"//g' -e 's/ //g' -e 's/,/\n/g' | tr '}' '\n' | tr '{' '\n')

    # Filter tags that has this string (optional)
    if [ -n "$only" ]; then
        tags=$(echo "${tags}" | grep "$only")
    fi

    # Exclude tags that has this string (optional)
    if [ -n "$exclude" ]; then
        tags=$(echo "${tags}" | grep -v "$exclude")
    fi

    local tagsWithTS=""
    local keepTS=0
    if [ -n "$tags" ]; then
        # timestamp
        if [ -n "$timestampMin" ]; then
            local timestamp_min=$(date -d "$timestampMin" +%s)
        fi
        # Get created timestamp for each tag
        for tag in $tags; do
            local created_time=$(curl -k -s -u $user:$password -H 'Accept: application/vnd.docker.distribution.manifest.v1+json' -X GET $registry/v2/$image/manifests/$tag | grep -i v1Compatibility | head -n1 | awk -F'created' '{print $2}' | awk -F'"' '{print $3}' | sed -e 's/\\//g')
            created_time=$(echo $created_time | sed -e 's/T/ /g' | awk -F'.' '{print $1}')
            local created_timestamp=$(date -d "$created_time" +%s)
            if [ -n "$timestampMin" ]; then
                if [ "$created_timestamp" -lt "$timestamp_min" ]; then
                    tagsWithTS="${tagsWithTS}${created_timestamp}|${tag} "
                else
                    ((keepTS++))
                fi
            else
                tagsWithTS="${tagsWithTS}${created_timestamp}|${tag} "
            fi
        done

        #Sort tags by time stamp and remove from list keeplast values, keeping tags to remove
        if [ "$keepTS" -gt "$keeplast" ]; then
            keeplast=0
        else
            keeplast=$((keeplast - keepTS))
        fi
        tagsWithTS=$(echo $tagsWithTS | xargs -n1 | sort -r -n -t'|' -k1)
        tagsWithTS=$(echo $tagsWithTS | xargs -n1 | sed -n $((keeplast + 1)),1000p)

        # Tags to remove
        local lasttagdigest=""
        if [ -n "$tagsWithTS" ]; then
            echo "The following image digests will be deleted:"
            for tagWithTS in $tagsWithTS; do
                timestamp=$(echo "$tagWithTS" | awk -F'|' '{print $1}')
                formatted_timestamp=$(date -d "@$timestamp" +%Y-%m-%d\ %H:%M:%S)
                tag=$(echo "$tagWithTS" | awk -F'|' '{print $2}')
                local tagdigest=$(curl -s -k -I -u "$user:$password" -H "Accept: application/vnd.docker.distribution.manifest.v2+json" "${registry}/v2/${image}/manifests/${tag}" | grep -i 'docker-content-digest: ' | awk -F': ' '{print $2}' | sed 's/[\r\n]//g')
                local url="${registry}/v2/${image}/manifests/${tagdigest}"
                if [ "$delete" = true ]; then
                    if [ "$tagdigest" != "$lasttagdigest" ]; then
                        curl -s -k -u "$user:$password" -X DELETE $url
                    fi
                    echo "  Deleted tag: ${formatted_timestamp} - ${image}:${tag}"
                else
                    echo "  ${formatted_timestamp} - ${image}:${tag}"
                fi
            done
        else
            echo "No image digests to be deleted"
        fi
    else
        echo "No tags found for image: ${image}"
    fi

}

HELPMSG="
    Basic usage
        $0 -r {registry_url} -i {image-name}
    Options avaliable
        -h    help on how to use the command
        -r    (required) registry url
        -i    (required) image name
        -k    keep last n (default 10)
        -t    keep tags with timestamp >= t
        -o    keep only tags that contains this string
        -e    exclude tags if name contains this string
        -u    user
        -p    password
        -d    delete the manifests, otherwise dryrun to only show info
    Examples
        $0 -r http://registry.local:5000 -i test -k 0
        $0 -r https://registry.example.com -i dev/test -e latest -d
"

# Initialize variables
registry=""
image=""
keeplast=""
timestampMin=""
only=""
exclude=""
user=""
password=""
delete=false

while getopts "hr:i:k:t:o:e:u:p:d" opt; do
    case "$opt" in
        h) echo "$HELPMSG"; exit 0 ;;
        r) registry="$OPTARG" ;;
        i) image="$OPTARG" ;;
        k) keeplast="$OPTARG" ;;
        t) timestampMin="$OPTARG" ;;
        o) only="$OPTARG" ;;
        e) exclude="$OPTARG" ;;
        u) user="$OPTARG" ;;
        p) password="$OPTARG" ;;
        d) delete=true ;;
        \?) echo "Invalid option: -$OPTARG" >&2; exit 1 ;;
    esac
done

# Set keeplast default value to 10
if [ -z "$keeplast" ]; then keeplast=5; fi

# Required params
if [ -z "$registry" ]; then echo "Error: Registry (-r) required"; echo "$HELPMSG"; exit 1; fi
if [ -z "$image" ]; then echo "Error: Image (-i) required"; echo "$HELPMSG"; exit 1; fi

check_tags_more_than_n_versions