132 lines
4.2 KiB
Python
132 lines
4.2 KiB
Python
from util.gzipwrap import GzipWrap, GZIP_BUFFER_SIZE
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from util.streamlayerformat import StreamLayerMerger
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from app import app
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import copy
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import json
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import tarfile
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class FileEstimationException(Exception):
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""" Exception raised by build_docker_load_stream if the estimated size of the layer TAR
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was lower than the actual size. This means the sent TAR header is wrong, and we have
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to fail.
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"""
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pass
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def build_docker_load_stream(namespace, repository, tag, synthetic_image_id,
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layer_json, get_image_iterator, get_layer_iterator):
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""" Builds and streams a synthetic .tar.gz that represents a squashed version
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of the given layers, in `docker load` V1 format.
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"""
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return GzipWrap(_import_format_generator(namespace, repository, tag,
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synthetic_image_id, layer_json,
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get_image_iterator, get_layer_iterator))
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def _import_format_generator(namespace, repository, tag, synthetic_image_id,
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layer_json, get_image_iterator, get_layer_iterator):
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# Docker import V1 Format (.tar):
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# repositories - JSON file containing a repo -> tag -> image map
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# {image ID folder}:
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# json - The layer JSON
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# layer.tar - The TARed contents of the layer
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# VERSION - The docker import version: '1.0'
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layer_merger = StreamLayerMerger(get_layer_iterator)
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# Yield the repositories file:
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synthetic_layer_info = {}
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synthetic_layer_info[tag + '.squash'] = synthetic_image_id
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hostname = app.config['SERVER_HOSTNAME']
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repositories = {}
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repositories[hostname + '/' + namespace + '/' + repository] = synthetic_layer_info
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yield _tar_file('repositories', json.dumps(repositories))
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# Yield the image ID folder.
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yield _tar_folder(synthetic_image_id)
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# Yield the JSON layer data.
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layer_json = _build_layer_json(layer_json, synthetic_image_id)
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yield _tar_file(synthetic_image_id + '/json', json.dumps(layer_json))
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# Yield the VERSION file.
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yield _tar_file(synthetic_image_id + '/VERSION', '1.0')
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# Yield the merged layer data's header.
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estimated_file_size = 0
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for image in get_image_iterator():
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estimated_file_size += image.storage.uncompressed_size
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yield _tar_file_header(synthetic_image_id + '/layer.tar', estimated_file_size)
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# Yield the contents of the merged layer.
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yielded_size = 0
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for entry in layer_merger.get_generator():
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yield entry
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yielded_size += len(entry)
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# If the yielded size is more than the estimated size (which is unlikely but possible), then
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# raise an exception since the tar header will be wrong.
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if yielded_size > estimated_file_size:
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raise FileEstimationException()
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# If the yielded size is less than the estimated size (which is likely), fill the rest with
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# zeros.
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if yielded_size < estimated_file_size:
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to_yield = estimated_file_size - yielded_size
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while to_yield > 0:
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yielded = min(to_yield, GZIP_BUFFER_SIZE)
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yield '\0' * yielded
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to_yield -= yielded
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# Yield any file padding to 512 bytes that is necessary.
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yield _tar_file_padding(estimated_file_size)
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# Last two records are empty in TAR spec.
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yield '\0' * 512
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yield '\0' * 512
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def _build_layer_json(layer_json, synthetic_image_id):
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updated_json = copy.deepcopy(layer_json)
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updated_json['id'] = synthetic_image_id
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if 'parent' in updated_json:
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del updated_json['parent']
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if 'config' in updated_json and 'Image' in updated_json['config']:
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updated_json['config']['Image'] = synthetic_image_id
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if 'container_config' in updated_json and 'Image' in updated_json['container_config']:
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updated_json['container_config']['Image'] = synthetic_image_id
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return updated_json
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def _tar_file(name, contents):
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length = len(contents)
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tar_data = _tar_file_header(name, length)
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tar_data += contents
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tar_data += _tar_file_padding(length)
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return tar_data
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def _tar_file_padding(length):
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if length % 512 != 0:
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return '\0' * (512 - (length % 512))
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return ''
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def _tar_file_header(name, file_size):
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info = tarfile.TarInfo(name=name)
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info.type = tarfile.REGTYPE
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info.size = file_size
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return info.tobuf()
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def _tar_folder(name):
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info = tarfile.TarInfo(name=name)
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info.type = tarfile.DIRTYPE
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return info.tobuf()
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