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# Copyright (C) 2023 Microsoft Corporation.
#
# This file is part of cloud-init. See LICENSE file for license information.
import enum
import logging
import os
import uuid
from typing import Optional
from cloudinit import dmi
from cloudinit.sources.helpers.azure import report_diagnostic_event
LOG = logging.getLogger(__name__)
def byte_swap_system_uuid(system_uuid: str) -> str:
"""Byte swap system uuid.
Azure always uses little-endian for the first three fields in the uuid.
This behavior was made strict in SMBIOS 2.6+, but Linux and dmidecode
follow RFC 4122 and assume big-endian for earlier SMBIOS versions.
Azure's gen1 VMs use SMBIOS 2.3 which requires byte swapping to match
compute.vmId presented by IMDS.
Azure's gen2 VMs use SMBIOS 3.1 which does not require byte swapping.
:raises ValueError: if UUID is invalid.
"""
try:
original_uuid = uuid.UUID(system_uuid)
except ValueError:
msg = f"Failed to parse system uuid: {system_uuid!r}"
report_diagnostic_event(msg, logger_func=LOG.error)
raise
return str(uuid.UUID(bytes=original_uuid.bytes_le))
def convert_system_uuid_to_vm_id(system_uuid: str) -> str:
"""Determine VM ID from system uuid."""
if is_vm_gen1():
return byte_swap_system_uuid(system_uuid)
return system_uuid
def is_vm_gen1() -> bool:
"""Determine if VM is gen1 or gen2.
Gen2 guests use UEFI while gen1 is legacy BIOS.
"""
# Linux
if os.path.exists("/sys/firmware/efi"):
return False
# BSD
if os.path.exists("/dev/efi"):
return False
return True
def query_system_uuid() -> str:
"""Query system uuid in lower-case."""
system_uuid = dmi.read_dmi_data("system-uuid")
if system_uuid is None:
raise RuntimeError("failed to read system-uuid")
# Kernels older than 4.15 will have upper-case system uuid.
system_uuid = system_uuid.lower()
LOG.debug("Read product uuid: %s", system_uuid)
return system_uuid
def query_vm_id() -> str:
"""Query VM ID from system."""
system_uuid = query_system_uuid()
return convert_system_uuid_to_vm_id(system_uuid)
class ChassisAssetTag(enum.Enum):
AZURE_CLOUD = "7783-7084-3265-9085-8269-3286-77"
@classmethod
def query_system(cls) -> Optional["ChassisAssetTag"]:
"""Check platform environment to report if this datasource may run.
:returns: ChassisAssetTag if matching tag found, else None.
"""
asset_tag = dmi.read_dmi_data("chassis-asset-tag")
try:
tag = cls(asset_tag)
except ValueError:
report_diagnostic_event(
"Non-Azure chassis asset tag: %r" % asset_tag,
logger_func=LOG.debug,
)
return None
report_diagnostic_event(
"Azure chassis asset tag: %r (%s)" % (asset_tag, tag.name),
logger_func=LOG.debug,
)
return tag