Deleting unused image tags from Google Container Registry, leaving x number left

gcr-cleaner.sh

#!/bin/bash

IFS=$'\n\t'
set -eou pipefail

if [[ "$#" -ne 3 || "${1}" == '-h' || "${1}" == '--help' ]]; then
	cat >&2 <<"EOF"

gcr-cleaner.sh will cleans up the gcr tags or untaged images pushed in a repository (image name with the specific tag)
and except the given number most recent images.

USAGE:
  ./gcr-cleaner.sh IMAGE_NAME IMAGE_TAG NUMBER_OF_IMAGES_TO_REMAIN
EXAMPLE:
  ./gcr-cleaner.sh asia.gcr.io/adept-primer-345706/alpine service1-develop 10

IMPACT:
  Would clean up everything under the repository tag asia.gcr.io/test-project/alpine:service1-develop~
  pushed except for the 10 most recent images. If image have multiple tag will be delete all tags.

EOF
	exit 1
fi

main() {
	local C=0
	IMAGE="${1}"
	IMAGE_TAG="${2}"
	NUMBER_OF_IMAGES_TO_REMAIN=$((${3} - 1))

	# 1. Get date and time the image want to retain
	CUTOFF=$(
		gcloud container images list-tags $IMAGE \
		--limit=unlimited \
		--sort-by=~TIMESTAMP \
		--flatten="[].tags[]" \
		--filter="tags~$IMAGE_TAG" \
		--format=json | TZ=/usr/share/zoneinfo/UTC jq -r '.['$NUMBER_OF_IMAGES_TO_REMAIN'].timestamp.datetime | sub("(?<before>.*):"; .before ) | strptime("%Y-%m-%d %H:%M:%S%z") | mktime | strftime("%Y-%m-%d %H:%M:%S%z")'		
	)
	# sample output: 2022-03-29 00:40:05+0000

	# 2. Get the image list (digest format)
	IMAGE_TAG_LIST=$(
		gcloud container images list-tags $IMAGE \
		--limit=unlimited \
		--sort-by=~TIMESTAMP \
		--flatten="[].tags[]" \
		--filter="tags~$IMAGE_TAG AND timestamp.datetime < '${CUTOFF}'" \
		--format="get(digest)"
	)
	# sample output: sha256:d72e2d383f2d5fb1e8186ebfd1fbb22a87c04f52ac12fc379d21abb368d373df

	# 3. List of images digest want to delete
	echo "you will be delete the images tag with digest below:"
	for digest in $IMAGE_TAG_LIST; do
		(
			set -x
			echo $digest
		)
		let C=C+1
	done
	echo "Total image to delete: ${C} images in ${IMAGE}:$IMAGE_TAG~."
	
	# 4. Delete the image digest based on filter
	echo "are you sure to delete it (y/n): "
	read ans
	if [ "$ans" == "y" ]; then
		for digest in $IMAGE_TAG_LIST; do
			(
				set -x
				gcloud container images delete -q --force-delete-tags "${IMAGE}@${digest}"
			)
			let C=C+1
		done
		echo "deleted ${C} images in ${IMAGE}:$IMAGE_TAG~." >&2
	else
		echo "INFO: Cancel the execution. Exit without any action"
		exit 0
	fi
}

main ${1} ${2} ${3}

Inspired by https://gist.github.com/DaanGeurts/d95f67578d0e6f39fee05ff5e2375dc3

Hi
How can we list child repository if we have multiple images?

Hi How can we list child repository if we have multiple images?

Can you give me a sample of the child repository?

eu.gcr.io/gcr-clean-repo/base
eu.gcr.io/gcr-clean-repo/base/alpine/image-digest
eu.gcr.io/gcr-clean-repo/base/mysql/image-digest
eu.gcr.io/gcr-clean-repo/base-2
eu.gcr.io/gcr-clean-repo/base-2/java/image-digest
eu.gcr.io/gcr-clean-repo/base-2/ruby/image-digest