Upload image to registry with uncompressed layers

upload-as-uncompressed.py

#!/usr/bin/env python3

import os
import subprocess
import requests
import json
import gzip
import hashlib

SOURCE_IMAGE = 'docker://alpine:latest'
DEST_REGISTRY_URL = 'https://registry.192-168-1-130.nip.io:8443'
DEST_REPO_NAME = 'uncompressed-alpine'
DEST_REPO_TAG = 'latest'
BUF_SIZE = 100000

# unzip compressed layer,
# return hash over unzipped data and uncompressed size
def uncompressed_layer_info(compressed_file):
    with gzip.open(compressed_file, 'rb') as f:
        buf = f.read(BUF_SIZE)
        uncompressed_size = len(buf)
        h = hashlib.sha256()
        while len(buf) > 0:
            h.update(buf)
            buf = f.read(BUF_SIZE)
            uncompressed_size = uncompressed_size + len(buf)

    return 'sha256:' + h.hexdigest(), uncompressed_size

# upload blob to registry
def upload_blob(registry_url, repo, filehandle, digest):
    # initiate upload
    r = requests.post(
        f'{registry_url}/v2/{repo}/blobs/uploads/',
        verify=False)

    upload_url = r.headers['Location']

    # upload file
    requests.put(
        upload_url,
        headers={'Content-Type': 'application/octet-stream'},
        params={'digest': digest},
        data=filehandle,
        verify=False)


# download image
subprocess.call(f'skopeo copy {SOURCE_IMAGE} dir:input', shell=True)

with open('input/manifest.json') as m:
    manifest = json.load(m)

    # upload uncompressed layers
    for layer in manifest['layers']:
        layer_filename = os.path.join('input', layer['digest'].split(':')[1])
        digest, size = uncompressed_layer_info(layer_filename)

        with gzip.open(layer_filename) as f:
            upload_blob(DEST_REGISTRY_URL, DEST_REPO_NAME, f, digest)

        # update manifest with uncompressed layer info
        layer['mediaType'] = 'application/vnd.docker.image.rootfs.diff.tar'
        layer['digest'] = digest
        layer['size'] = size

    # upload image config
    digest = manifest['config']['digest']
    config_filename = os.path.join('input', digest.split(':')[1])
    with open(config_filename) as f:
        upload_blob(DEST_REGISTRY_URL, DEST_REPO_NAME, f, digest)

    # upload manifest with uncompressed layer references
    requests.put(
        f'{DEST_REGISTRY_URL}/v2/{DEST_REPO_NAME}/manifests/{DEST_REPO_TAG}',
        headers={'Content-Type': 'application/vnd.docker.distribution.manifest.v2+json'},
        json=manifest,
        verify=False)