Container Infrastructure Management Service for OpenStack
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#
# 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.
"""Utilities for creating short ID strings based on a random UUID.
The IDs each comprise 12 (lower-case) alphanumeric characters.
"""
import base64
import uuid
import six
from magnum.i18n import _
def _to_byte_string(value, num_bits):
"""Convert an integer to a big-endian string of bytes with padding.
Padding is added at the end (i.e. after the least-significant bit) if
required.
"""
shifts = six.moves.xrange(num_bits - 8, -8, -8)
byte_at = lambda off: (value >> off if off >= 0 else value << -off) & 0xff
return ''.join(chr(byte_at(offset)) for offset in shifts)
def get_id(source_uuid):
"""Derive a short (12 character) id from a random UUID.
The supplied UUID must be a version 4 UUID object.
"""
if isinstance(source_uuid, six.string_types):
source_uuid = uuid.UUID(source_uuid)
if source_uuid.version != 4:
raise ValueError(_('Invalid UUID version (%d)') % source_uuid.version)
# The "time" field of a v4 UUID contains 60 random bits
# (see RFC4122, Section 4.4)
random_bytes = _to_byte_string(source_uuid.time, 60)
# The first 12 bytes (= 60 bits) of base32-encoded output is our data
encoded = base64.b32encode(random_bytes)[:12]
return encoded.lower()
def generate_id():
"""Generate a short (12 character), random id."""
return get_id(uuid.uuid4())