mogan/mogan/engine/configdrive.py

# Copyright 2012 Michael Still and Canonical Inc
# 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.

'''
Leverages nova/virt/configdrive.py by Michael Still
'''

"""Config Drive v2 helper."""

import os
import shutil

from oslo_utils import fileutils
from oslo_utils import units
import six

from mogan.common import exception
from mogan.common import utils
from mogan.conf import CONF
from mogan import version


# Config drives are 64mb, if we can't size to the exact size of the data
CONFIGDRIVESIZE_BYTES = 64 * units.Mi


class ConfigDriveBuilder(object):
    """Build config drives, optionally as a context manager."""

    def __init__(self, server_md=None):
        self.imagefile = None
        self.mdfiles = []

        if server_md is not None:
            self.add_server_metadata(server_md)

    def __enter__(self):
        return self

    def __exit__(self, exctype, excval, exctb):
        if exctype is not None:
            # NOTE(mikal): this means we're being cleaned up because an
            # exception was thrown. All bets are off now, and we should not
            # swallow the exception
            return False
        self.cleanup()

    def _add_file(self, basedir, path, data):
        filepath = os.path.join(basedir, path)
        dirname = os.path.dirname(filepath)
        fileutils.ensure_tree(dirname)
        with open(filepath, 'wb') as f:
            # the given data can be either text or bytes. we can only write
            # bytes into files.
            if isinstance(data, six.text_type):
                data = data.encode('utf-8')
            f.write(data)

    def add_server_metadata(self, server_md):
        for (path, data) in server_md.metadata_for_config_drive():
            self.mdfiles.append((path, data))

    def _write_md_files(self, basedir):
        for data in self.mdfiles:
            self._add_file(basedir, data[0], data[1])

    def _make_iso9660(self, path, tmpdir):
        publisher = "%(product)s %(version)s" % {
            'product': version.product_string(),
            'version': version.version_string_with_package()}

        utils.execute(CONF.configdrive.mkisofs_cmd,
                      '-o', path,
                      '-ldots',
                      '-allow-lowercase',
                      '-allow-multidot',
                      '-l',
                      '-publisher',
                      publisher,
                      '-quiet',
                      '-J',
                      '-r',
                      '-V', 'config-2',
                      tmpdir,
                      attempts=1,
                      run_as_root=False)

    def _make_vfat(self, path, tmpdir):
        # NOTE(mikal): This is a little horrible, but I couldn't find an
        # equivalent to genisoimage for vfat filesystems.
        with open(path, 'wb') as f:
            f.truncate(CONFIGDRIVESIZE_BYTES)

        utils.mkfs('vfat', path, label='config-2')

        with utils.tempdir() as mountdir:
            mounted = False
            try:
                _, err = utils.trycmd(
                    'mount', '-o', 'loop,uid=%d,gid=%d' % (os.getuid(),
                                                           os.getgid()),
                    path,
                    mountdir,
                    run_as_root=True)
                if err:
                    raise exception.ConfigDriveMountFailed(operation='mount',
                                                           error=err)
                mounted = True

                # NOTE(mikal): I can't just use shutils.copytree here,
                # because the destination directory already
                # exists. This is annoying.
                for ent in os.listdir(tmpdir):
                    shutil.copytree(os.path.join(tmpdir, ent),
                                    os.path.join(mountdir, ent))

            finally:
                if mounted:
                    utils.execute('umount', mountdir, run_as_root=True)

    def make_drive(self, path):
        """Make the config drive.

        :param path: the path to place the config drive image at

        :raises ProcessExecuteError if a helper process has failed.
        """
        with utils.tempdir() as tmpdir:
            self._write_md_files(tmpdir)

            if CONF.configdrive.config_drive_format == 'iso9660':
                self._make_iso9660(path, tmpdir)
            elif CONF.configdrive.config_drive_format == 'vfat':
                self._make_vfat(path, tmpdir)
            else:
                raise exception.ConfigDriveUnknownFormat(
                    format=CONF.configdrive.config_drive_format)

    def cleanup(self):
        if self.imagefile:
            fileutils.delete_if_exists(self.imagefile)

    def __repr__(self):
        return "<ConfigDriveBuilder: " + str(self.mdfiles) + ">"