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# Copyright 2015 The Bazel Authors. All rights reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""This tool creates a docker image from a layer and the various metadata."""
import sys
import tarfile
from tools.build_defs.docker import archive
from third_party.py import gflags
# Hardcoded docker versions that we are claiming to be.
DATA_FORMAT_VERSION = '1.0'
gflags.DEFINE_string(
'output', None,
'The output file, mandatory')
gflags.MarkFlagAsRequired('output')
gflags.DEFINE_string(
'metadata', None,
'The JSON metadata file for this image, mandatory.')
gflags.MarkFlagAsRequired('metadata')
gflags.DEFINE_string(
'layer', None,
'The tar file for the top layer of this image, mandatory.')
gflags.MarkFlagAsRequired('metadata')
gflags.DEFINE_string(
'id', None,
'The hex identifier of this image (hexstring or @filename), mandatory.')
gflags.MarkFlagAsRequired('id')
gflags.DEFINE_string(
'base', None,
'The base image file for this image.')
gflags.DEFINE_string(
'repository', None,
'The name of the repository to add this image.')
gflags.DEFINE_string(
'name', None,
'The symbolic name of this image.')
FLAGS = gflags.FLAGS
def _base_name_filter(name):
"""Do not add multiple times 'top' and 'repositories' when merging images."""
filter_names = ['top', 'repositories']
return all([not name.endswith(s) for s in filter_names])
def create_image(output, identifier,
base=None, layer=None, metadata=None,
name=None, repository=None):
"""Creates a Docker image.
Args:
output: the name of the docker image file to create.
identifier: the identifier of the top layer for this image.
base: a base layer (optional) to merge to current layer.
layer: the layer content (a tar file).
metadata: the json metadata file for the top layer.
name: symbolic name for this docker image.
repository: repository name for this docker image.
"""
tar = archive.TarFileWriter(output)
# Write our id to 'top' as we are now the topmost layer.
tar.add_file('top', content=identifier)
# Each layer is encoded as a directory in the larger tarball of the form:
# {id}\
# layer.tar
# VERSION
# json
# Create the directory for us to now fill in.
tar.add_file(identifier + '/', tarfile.DIRTYPE)
# VERSION generally seems to contain 1.0, not entirely sure
# what the point of this is.
tar.add_file(identifier + '/VERSION', content=DATA_FORMAT_VERSION)
# Add the layer file
tar.add_file(identifier + '/layer.tar', file_content=layer)
# Now the json metadata
tar.add_file(identifier + '/json', file_content=metadata)
# Merge the base if any
if base:
tar.add_tar(base, name_filter=_base_name_filter)
# In addition to N layers of the form described above, there is
# a single file at the top of the image called repositories.
# This file contains a JSON blob of the form:
# {
# 'repo':{
# 'tag-name': 'top-most layer hex',
# ...
# },
# ...
# }
if repository:
tar.add_file('repositories', content='\n'.join([
'{',
' "%s": {' % repository,
' "%s": "%s"' % (name, identifier),
' }',
'}']))
# Main program to create a docker image. It expect to be run with:
# create_image --output=output_file \
# --id=@identifier \
# [--base=base] \
# --layer=layer.tar \
# --metadata=metadata.json \
# --name=myname --repository=repositoryName
# See the gflags declaration about the flags argument details.
def main(unused_argv):
identifier = FLAGS.id
if identifier.startswith('@'):
with open(identifier[1:], 'r') as f:
identifier = f.read()
create_image(FLAGS.output, identifier, FLAGS.base,
FLAGS.layer, FLAGS.metadata,
FLAGS.name, FLAGS.repository)
if __name__ == '__main__':
main(FLAGS(sys.argv))
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