Source code for heat.common.short_id

#    Licensed under the Apache License, Version 2.0 (the "License"); you may
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"""Utilities for creating short ID strings based on a random UUID.

The IDs each comprise 12 (lower-case) alphanumeric characters.

import base64
import uuid

from heat.common.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
    shifts = range(num_bits - 8, -8, -8)

    def byte_at(off):
        return (value >> off if off >= 0 else value << -off) & 0xff

    return b''.join(bytes((byte_at(offset),)) for offset in shifts)

[docs]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, str): 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_bytes = base64.b32encode(random_bytes)[:12] return encoded_bytes.decode('ascii').lower()
[docs]def generate_id(): """Generate a short (12 character), random id.""" return get_id(uuid.uuid4())