#!/usr/bin/env python

import json

import boto3


DOCKER_BUCKET = 'docker-registry'


def main(s3):
    bucket = s3.Bucket(DOCKER_BUCKET)

    used_images = set()
    for key in bucket.objects.filter(Prefix='registry/repositories'):
        if (key.key.endswith('/_index_images')):
            data = json.loads(key.get()['Body'].read().decode('utf-8'))
            for item in data:
                used_images.update([item.get('id')])

    for key in bucket.objects.filter(Prefix='registry/images'):
        image_id = key.key.split('/', 3)[2]

        if image_id not in used_images:
            print(key.key)
            key.delete()


if __name__ == '__main__':
    main(boto3.resource('s3'))