Get the latest Minecraft server.jar (including snapshots)

download_minecraft_server_jar.py

#!/usr/bin/python3
#
# SPDX-FileCopyrightText: 2021 Stephan Lachnit <stephanlachnit@debian.org>
#
# SPDX-License-Identifier: MIT


import hashlib
import os.path
import sys
import requests


# set false if release version should be selected by default
prefer_snapshot = True

# download folder for server.jar
download_folder = '.'

# url for version_manifest_v2.json
version_manifest_url = 'https://launchermeta.mojang.com/mc/game/version_manifest_v2.json'

# chunk size for download and checksum iterations
iter_chunk_size = 65536


if __name__ == '__main__':
    print('Fetching version manifest')

    # get the version manifest
    _response = requests.get(version_manifest_url)

    if _response.status_code != requests.codes.ok:
        raise Exception('Could not download version manifest, please check your internet connection')

    version_manifest = _response.json()

    # get latest version
    version_type = 'release'
    if prefer_snapshot:
        version_type = 'snapshot'

    version_id_latest = version_manifest['latest'][version_type]

    # ask which version to download
    version_id_requested = input(f'Download version [{version_id_latest}]: ')
    if version_id_requested == '':
        version_id_requested = version_id_latest

    # loop versions for requested version
    version_found = False
    version_url = str()

    for _version in version_manifest['versions']:
        if _version['id'] == version_id_requested:
            version_found = True
            version_url = _version['url']
            break

    if not version_found:
        raise Exception(f'Version {version_id_requested} not found')

    # download version information
    version_json = requests.get(version_url).json()

    # get server.jar download url, size and checksum
    server_jar_url = version_json['downloads']['server']['url']
    server_jar_size = version_json['downloads']['server']['size']
    server_jar_sha1 = version_json['downloads']['server']['sha1']

    print(f'Downloading server.jar for version {version_id_requested} ({float(server_jar_size)/(1024**2):.0f} MB)')

    download_server_jar_size = 0
    download_server_jar_sha1 = hashlib.sha1()

    # download server jar in chunks
    with open(os.path.join(download_folder, 'server.jar'), 'wb') as _server_jar:
        _response = requests.get(server_jar_url, stream=True)

        # write chunks and update progress
        for chunk in _response.iter_content(chunk_size=iter_chunk_size):
            _server_jar.write(chunk)

            download_server_jar_size += len(chunk)

            # update progress bar
            downloaded_perc_n50 = int(50 * download_server_jar_size / server_jar_size)

            sys.stdout.write('\r['+('=' * downloaded_perc_n50)+(' ' * (50 - downloaded_perc_n50))+f'] ({download_server_jar_size} / {server_jar_size})')
            sys.stdout.flush()

            # update sha1
            download_server_jar_sha1.update(chunk)

    print('\nDownload complete')

    print(f'Verifying server.jar (sha1 {server_jar_sha1})')

    # sanity check the size
    if download_server_jar_size != server_jar_size:
        raise Warning(f'Size mismatch ({download_server_jar_size} != {server_jar_size})')

    # check the checksum
    download_server_jar_sha1 = download_server_jar_sha1.hexdigest()

    if download_server_jar_sha1 != server_jar_sha1:
        raise Warning(f'Checksum mismatch ({download_server_jar_sha1} != {server_jar_sha1})')

    print('Verification complete')