Add schema2 manifest and schema2 config, along with tests
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Joseph Schorr
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6 changed files with 642 additions and 0 deletions
205
image/docker/schema2/manifest.py
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205
image/docker/schema2/manifest.py
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import json
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import logging
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import hashlib
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from collections import namedtuple
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from jsonschema import validate as validate_schema, ValidationError
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from digest import digest_tools
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from image.docker import ManifestException
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from image.docker.schema2 import (DOCKER_SCHEMA2_MANIFEST_CONTENT_TYPE,
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DOCKER_SCHEMA2_CONFIG_CONTENT_TYPE,
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DOCKER_SCHEMA2_LAYER_CONTENT_TYPE,
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DOCKER_SCHEMA2_REMOTE_LAYER_CONTENT_TYPE)
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from image.docker.schema2.config import DockerSchema2Config
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# Keys.
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DOCKER_SCHEMA2_MANIFEST_VERSION_KEY = 'schemaVersion'
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DOCKER_SCHEMA2_MANIFEST_MEDIATYPE_KEY = 'mediaType'
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DOCKER_SCHEMA2_MANIFEST_CONFIG_KEY = 'config'
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DOCKER_SCHEMA2_MANIFEST_SIZE_KEY = 'size'
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DOCKER_SCHEMA2_MANIFEST_DIGEST_KEY = 'digest'
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DOCKER_SCHEMA2_MANIFEST_LAYERS_KEY = 'layers'
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DOCKER_SCHEMA2_MANIFEST_URLS_KEY = 'urls'
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# Named tuples.
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DockerV2ManifestConfig = namedtuple('DockerV2ManifestConfig', ['size', 'digest'])
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DockerV2ManifestLayer = namedtuple('DockerV2ManifestLayer', ['index', 'size', 'digest',
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'is_remote', 'urls'])
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LayerWithV1ID = namedtuple('LayerWithV1ID', ['layer', 'v1_id', 'v1_parent_id'])
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logger = logging.getLogger(__name__)
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class MalformedSchema2Manifest(ManifestException):
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"""
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Raised when a manifest fails an assertion that should be true according to the Docker Manifest
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v2.2 Specification.
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"""
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pass
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class DockerSchema2Manifest(object):
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METASCHEMA = {
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'type': 'object',
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'properties': {
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DOCKER_SCHEMA2_MANIFEST_VERSION_KEY: {
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'type': 'number',
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'description': 'The version of the schema. Must always be `2`.',
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'minimum': 2,
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'maximum': 2,
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},
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DOCKER_SCHEMA2_MANIFEST_MEDIATYPE_KEY: {
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'type': 'string',
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'description': 'The media type of the schema.',
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'enum': [DOCKER_SCHEMA2_MANIFEST_CONTENT_TYPE],
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},
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DOCKER_SCHEMA2_MANIFEST_CONFIG_KEY: {
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'type': 'object',
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'description': 'The config field references a configuration object for a container, ' +
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'by digest. This configuration item is a JSON blob that the runtime ' +
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'uses to set up the container.',
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'properties': {
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DOCKER_SCHEMA2_MANIFEST_MEDIATYPE_KEY: {
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'type': 'string',
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'description': 'The MIME type of the referenced object. This should generally be ' +
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'application/vnd.docker.container.image.v1+json',
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'enum': [DOCKER_SCHEMA2_CONFIG_CONTENT_TYPE],
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},
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DOCKER_SCHEMA2_MANIFEST_SIZE_KEY: {
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'type': 'number',
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'description': 'The size in bytes of the object. This field exists so that a ' +
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'client will have an expected size for the content before ' +
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'validating. If the length of the retrieved content does not ' +
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'match the specified length, the content should not be trusted.',
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},
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DOCKER_SCHEMA2_MANIFEST_DIGEST_KEY: {
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'type': 'string',
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'description': 'The content addressable digest of the config in the blob store',
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},
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},
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'required': [DOCKER_SCHEMA2_MANIFEST_MEDIATYPE_KEY, DOCKER_SCHEMA2_MANIFEST_SIZE_KEY,
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DOCKER_SCHEMA2_MANIFEST_DIGEST_KEY],
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},
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DOCKER_SCHEMA2_MANIFEST_LAYERS_KEY: {
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'type': 'array',
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'description': 'The layer list is ordered starting from the base ' +
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'image (opposite order of schema1).',
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'items': {
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'type': 'object',
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'properties': {
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DOCKER_SCHEMA2_MANIFEST_MEDIATYPE_KEY: {
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'type': 'string',
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'description': 'The MIME type of the referenced object. This should generally be ' +
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'application/vnd.docker.image.rootfs.diff.tar.gzip. Layers of type ' +
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'application/vnd.docker.image.rootfs.foreign.diff.tar.gzip may be ' +
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'pulled from a remote location but they should never be pushed.',
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'enum': [DOCKER_SCHEMA2_LAYER_CONTENT_TYPE, DOCKER_SCHEMA2_REMOTE_LAYER_CONTENT_TYPE],
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},
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DOCKER_SCHEMA2_MANIFEST_SIZE_KEY: {
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'type': 'number',
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'description': 'The size in bytes of the object. This field exists so that a ' +
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'client will have an expected size for the content before ' +
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'validating. If the length of the retrieved content does not ' +
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'match the specified length, the content should not be trusted.',
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},
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DOCKER_SCHEMA2_MANIFEST_DIGEST_KEY: {
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'type': 'string',
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'description': 'The content addressable digest of the layer in the blob store',
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},
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},
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'required': [
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DOCKER_SCHEMA2_MANIFEST_MEDIATYPE_KEY, DOCKER_SCHEMA2_MANIFEST_SIZE_KEY,
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DOCKER_SCHEMA2_MANIFEST_DIGEST_KEY,
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],
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},
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},
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},
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'required': [DOCKER_SCHEMA2_MANIFEST_VERSION_KEY, DOCKER_SCHEMA2_MANIFEST_MEDIATYPE_KEY,
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DOCKER_SCHEMA2_MANIFEST_CONFIG_KEY, DOCKER_SCHEMA2_MANIFEST_LAYERS_KEY],
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}
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def __init__(self, manifest_bytes):
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self._layers = None
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try:
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self._parsed = json.loads(manifest_bytes)
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except ValueError as ve:
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raise MalformedSchema2Manifest('malformed manifest data: %s' % ve)
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try:
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validate_schema(self._parsed, DockerSchema2Manifest.METASCHEMA)
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except ValidationError as ve:
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raise MalformedSchema2Manifest('manifest data does not match schema: %s' % ve)
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@property
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def config(self):
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config = self._parsed[DOCKER_SCHEMA2_MANIFEST_CONFIG_KEY]
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return DockerV2ManifestConfig(size=config[DOCKER_SCHEMA2_MANIFEST_SIZE_KEY],
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digest=config[DOCKER_SCHEMA2_MANIFEST_DIGEST_KEY])
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@property
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def layers(self):
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""" Returns the layers of this manifest, from base to leaf. """
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if self._layers is None:
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self._layers = list(self._generate_layers())
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return self._layers
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@property
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def leaf_layer(self):
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return self.layers[-1]
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def _generate_layers(self):
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for index, layer in enumerate(self._parsed[DOCKER_SCHEMA2_MANIFEST_LAYERS_KEY]):
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content_type = layer[DOCKER_SCHEMA2_MANIFEST_MEDIATYPE_KEY]
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is_remote = content_type == DOCKER_SCHEMA2_REMOTE_LAYER_CONTENT_TYPE
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try:
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digest = digest_tools.Digest.parse_digest(layer[DOCKER_SCHEMA2_MANIFEST_DIGEST_KEY])
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except digest_tools.InvalidDigestException:
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raise MalformedSchema2Manifest('could not parse manifest digest: %s' %
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layer[DOCKER_SCHEMA2_MANIFEST_DIGEST_KEY])
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yield DockerV2ManifestLayer(index=index,
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size=layer[DOCKER_SCHEMA2_MANIFEST_SIZE_KEY],
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digest=digest,
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is_remote=is_remote,
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urls=layer.get(DOCKER_SCHEMA2_MANIFEST_URLS_KEY))
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@property
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def layers_with_v1_ids(self):
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digest_history = hashlib.sha256()
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v1_layer_parent_id = None
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v1_layer_id = None
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for layer in self.layers:
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v1_layer_parent_id = v1_layer_id
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# Create a new synthesized V1 ID for the layer by adding its digest and index to the
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# existing digest history hash builder. This will ensure unique V1s across *all* schemas in
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# a repository.
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digest_history.update(str(layer.digest))
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digest_history.update("#")
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digest_history.update(str(layer.index))
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digest_history.update("|")
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v1_layer_id = digest_history.hexdigest()
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yield LayerWithV1ID(layer=layer, v1_id=v1_layer_id, v1_parent_id=v1_layer_parent_id)
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def populate_schema1_builder(self, v1_builder, lookup_config_fn):
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""" Populates a DockerSchema1ManifestBuilder with the layers and config from
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this schema. The `lookup_config_fn` is a function that, when given the config
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digest SHA, returns the associated configuration JSON bytes for this schema.
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"""
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config_bytes = lookup_config_fn(self.config.digest)
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schema2_config = DockerSchema2Config(config_bytes)
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# Build the V1 IDs for the layers.
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layers = list(self.layers_with_v1_ids)
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for layer_with_ids in reversed(layers): # Schema1 has layers in reverse order
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v1_compatibility = schema2_config.build_v1_compatibility(layer_with_ids.layer.index,
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layer_with_ids.v1_id,
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layer_with_ids.v1_parent_id)
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v1_builder.add_layer(str(layer_with_ids.layer.digest), json.dumps(v1_compatibility))
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return v1_builder
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