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Add LXD datasource (canonical#1040)
Add DataSourceLXD which knows how to talk to the dev-lxd socket to obtain all instance metadata API: https://linuxcontainers.org/lxd/docs/master/dev-lxd. This first branch is to deliver feature parity with the existing NoCloud datasource which is currently used to intialize LXC instances on first boot. Introduce a SocketConnectionPool and LXDSocketAdapter to support performing HTTP GETs on the following routes which are surfaced by the LXD host to all containers: http://unix.socket/1.0/meta-data http://unix.socket/1.0/config/user.user-data http://unix.socket/1.0/config/user.network-config http://unix.socket/1.0/config/user.vendor-data These 4 routes minimally replace the static content provided in the following nocloud-net seed files: /var/lib/cloud/nocloud-net/{meta-data,vendor-data,user-data,network-config} The intent of this commit is to set a foundation for LXD socket communication that will allow us to build network hot-plug features by eventually consuming LXD's websocket upgrade route 1.0/events to react to network, meta-data and user-data config changes over time. In the event that no custom network-config is provided, default to the same network-config definition provided by LXD to the NoCloud network-config seed file. Supplemental features above NoCloud datasource: surface all custom instance data config keys via cloud-init query ds which aids in discoverability of features/tags/labels as well as conditional #cloud-config jinja templates operations based on custom config options. TBD: better cloud-init query support for dot-delimited keys
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‎cloudinit/settings.py‎

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'datasource_list': [
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'NoCloud',
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'ConfigDrive',
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'LXD',
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'OpenNebula',
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'DigitalOcean',
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'Azure',

‎cloudinit/sources/DataSourceLXD.py‎

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"""Datasource for LXD, reads /dev/lxd/sock representaton of instance data.
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Notes:
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* This datasource replaces previous NoCloud datasource for LXD.
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* Older LXD images may not have updates for cloud-init so NoCloud may
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still be detected on those images.
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* Detect LXD datasource when /dev/lxd/sock is an active socket file.
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* Info on dev-lxd API: https://linuxcontainers.org/lxd/docs/master/dev-lxd
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* TODO( Hotplug support using websockets API 1.0/events )
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"""
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import os
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import requests
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from requests.adapters import HTTPAdapter
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# pylint fails to import the two modules below.
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# These are imported via requests.packages rather than urllib3 because:
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# a.) the provider of the requests package should ensure that urllib3
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# contained in it is consistent/correct.
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# b.) cloud-init does not specifically have a dependency on urllib3
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#
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# For future reference, see:
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# https://github.com/kennethreitz/requests/pull/2375
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# https://github.com/requests/requests/issues/4104
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# pylint: disable=E0401
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from requests.packages.urllib3.connection import HTTPConnection
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from requests.packages.urllib3.connectionpool import HTTPConnectionPool
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import socket
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import stat
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from cloudinit import log as logging
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from cloudinit import sources, subp, util
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LOG = logging.getLogger(__name__)
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LXD_SOCKET_PATH = "/dev/lxd/sock"
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LXD_SOCKET_API_VERSION = "1.0"
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# Config key mappings to alias as top-level instance data keys
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CONFIG_KEY_ALIASES = {
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"user.user-data": "user-data",
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"user.network-config": "network-config",
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"user.network_mode": "network_mode",
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"user.vendor-data": "vendor-data"
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}
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def generate_fallback_network_config(network_mode: str = "") -> dict:
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"""Return network config V1 dict representing instance network config."""
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network_v1 = {
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"version": 1,
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"config": [
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{
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"type": "physical", "name": "eth0",
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"subnets": [{"type": "dhcp", "control": "auto"}]
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}
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]
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}
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if subp.which("systemd-detect-virt"):
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try:
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virt_type, _ = subp.subp(['systemd-detect-virt'])
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except subp.ProcessExecutionError as err:
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LOG.warning(
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"Unable to run systemd-detect-virt: %s."
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" Rendering default network config.", err
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)
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return network_v1
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if virt_type.strip() == "kvm": # instance.type VIRTUAL-MACHINE
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arch = util.system_info()["uname"][4]
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if arch == "ppc64le":
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network_v1["config"][0]["name"] = "enp0s5"
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elif arch == "s390x":
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network_v1["config"][0]["name"] = "enc9"
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else:
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network_v1["config"][0]["name"] = "enp5s0"
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if network_mode == "link-local":
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network_v1["config"][0]["subnets"][0]["control"] = "manual"
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elif network_mode not in ("", "dhcp"):
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LOG.warning(
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"Ignoring unexpected value user.network_mode: %s", network_mode
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)
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return network_v1
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class SocketHTTPConnection(HTTPConnection):
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def __init__(self, socket_path):
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super().__init__('localhost')
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self.socket_path = socket_path
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def connect(self):
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self.sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
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self.sock.connect(self.socket_path)
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class SocketConnectionPool(HTTPConnectionPool):
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def __init__(self, socket_path):
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self.socket_path = socket_path
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super().__init__('localhost')
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def _new_conn(self):
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return SocketHTTPConnection(self.socket_path)
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class LXDSocketAdapter(HTTPAdapter):
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def get_connection(self, url, proxies=None):
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return SocketConnectionPool(LXD_SOCKET_PATH)
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def _maybe_remove_top_network(cfg):
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"""If network-config contains top level 'network' key, then remove it.
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Some providers of network configuration may provide a top level
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'network' key (LP: #1798117) even though it is not necessary.
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Be friendly and remove it if it really seems so.
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Return the original value if no change or the updated value if changed."""
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if "network" not in cfg:
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return cfg
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network_val = cfg["network"]
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bmsg = 'Top level network key in network-config %s: %s'
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if not isinstance(network_val, dict):
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LOG.debug(bmsg, "was not a dict", cfg)
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return cfg
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if len(list(cfg.keys())) != 1:
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LOG.debug(bmsg, "had multiple top level keys", cfg)
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return cfg
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if network_val.get('config') == "disabled":
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LOG.debug(bmsg, "was config/disabled", cfg)
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elif not all(('config' in network_val, 'version' in network_val)):
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LOG.debug(bmsg, "but missing 'config' or 'version'", cfg)
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return cfg
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LOG.debug(bmsg, "fixed by removing shifting network.", cfg)
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return network_val
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def _raw_instance_data_to_dict(metadata_type: str, metadata_value) -> dict:
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"""Convert raw instance data from str, bytes, YAML to dict
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:param metadata_type: string, one of as: meta-data, vendor-data, user-data
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network-config
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:param metadata_value: str, bytes or dict representing or instance-data.
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:raises: InvalidMetaDataError on invalid instance-data content.
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"""
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if isinstance(metadata_value, dict):
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return metadata_value
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if metadata_value is None:
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return {}
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try:
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parsed_metadata = util.load_yaml(metadata_value)
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except AttributeError as exc: # not str or bytes
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raise sources.InvalidMetaDataException(
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"Invalid {md_type}. Expected str, bytes or dict but found:"
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" {value}".format(md_type=metadata_type, value=metadata_value)
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) from exc
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if parsed_metadata is None:
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raise sources.InvalidMetaDataException(
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"Invalid {md_type} format. Expected YAML but found:"
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" {value}".format(md_type=metadata_type, value=metadata_value)
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)
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return parsed_metadata
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class DataSourceLXD(sources.DataSource):
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dsname = 'LXD'
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_network_config = sources.UNSET
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_crawled_metadata = sources.UNSET
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sensitive_metadata_keys = (
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'merged_cfg', 'user.meta-data', 'user.vendor-data', 'user.user-data',
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)
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def _is_platform_viable(self) -> bool:
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"""Check platform environment to report if this datasource may run."""
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return is_platform_viable()
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def _get_data(self) -> bool:
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"""Crawl LXD socket API instance data and return True on success"""
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if not self._is_platform_viable():
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LOG.debug("Not an LXD datasource: No LXD socket found.")
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return False
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self._crawled_metadata = util.log_time(
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logfunc=LOG.debug, msg='Crawl of metadata service',
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func=read_metadata)
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self.metadata = _raw_instance_data_to_dict(
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"meta-data", self._crawled_metadata.get("meta-data")
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)
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if LXD_SOCKET_API_VERSION in self._crawled_metadata:
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config = self._crawled_metadata[LXD_SOCKET_API_VERSION].get(
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"config", {}
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)
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user_metadata = config.get("user.meta-data", {})
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if user_metadata:
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user_metadata = _raw_instance_data_to_dict(
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"user.meta-data", user_metadata
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)
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if not isinstance(self.metadata, dict):
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self.metadata = util.mergemanydict(
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[util.load_yaml(self.metadata), user_metadata]
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)
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if "user-data" in self._crawled_metadata:
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self.userdata_raw = self._crawled_metadata["user-data"]
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if "network-config" in self._crawled_metadata:
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self._network_config = _maybe_remove_top_network(
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_raw_instance_data_to_dict(
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"network-config", self._crawled_metadata["network-config"]
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)
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)
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if "vendor-data" in self._crawled_metadata:
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self.vendordata_raw = self._crawled_metadata["vendor-data"]
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return True
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def _get_subplatform(self) -> str:
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"""Return subplatform details for this datasource"""
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return "LXD socket API v. {ver} ({socket})".format(
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ver=LXD_SOCKET_API_VERSION, socket=LXD_SOCKET_PATH
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)
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def check_instance_id(self, sys_cfg) -> str:
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"""Return True if instance_id unchanged."""
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response = read_metadata(metadata_only=True)
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md = response.get("meta-data", {})
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if not isinstance(md, dict):
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md = util.load_yaml(md)
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return md.get("instance-id") == self.metadata.get("instance-id")
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@property
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def network_config(self) -> dict:
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"""Network config read from LXD socket config/user.network-config.
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If none is present, then we generate fallback configuration.
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"""
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if self._network_config == sources.UNSET:
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if self._crawled_metadata.get("network-config"):
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self._network_config = self._crawled_metadata.get(
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"network-config"
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)
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else:
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network_mode = self._crawled_metadata.get("network_mode", "")
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self._network_config = generate_fallback_network_config(
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network_mode
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)
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return self._network_config
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def is_platform_viable() -> bool:
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"""Return True when this platform appears to have an LXD socket."""
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if os.path.exists(LXD_SOCKET_PATH):
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return stat.S_ISSOCK(os.lstat(LXD_SOCKET_PATH).st_mode)
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return False
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def read_metadata(
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api_version: str = LXD_SOCKET_API_VERSION, metadata_only: bool = False
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) -> dict:
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"""Fetch metadata from the /dev/lxd/socket routes.
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Perform a number of HTTP GETs on known routes on the devlxd socket API.
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Minimally all containers must respond to http://lxd/1.0/meta-data when
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the LXD configuration setting `security.devlxd` is true.
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When `security.devlxd` is false, no /dev/lxd/socket file exists. This
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datasource will return False from `is_platform_viable` in that case.
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Perform a GET of <LXD_SOCKET_API_VERSION>/config` and walk all `user.*`
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configuration keys, storing all keys and values under a dict key
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LXD_SOCKET_API_VERSION: config {...}.
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In the presence of the following optional user config keys,
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create top level aliases:
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- user.user-data -> user-data
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- user.vendor-data -> vendor-data
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- user.network-config -> network-config
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:return:
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A dict with the following mandatory key: meta-data.
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Optional keys: user-data, vendor-data, network-config, network_mode
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Below <LXD_SOCKET_API_VERSION> is a dict representation of all raw
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configuration keys and values provided to the container surfaced by
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the socket under the /1.0/config/ route.
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"""
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md = {}
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lxd_url = "http://lxd"
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version_url = lxd_url + "/" + api_version + "/"
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with requests.Session() as session:
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session.mount(version_url, LXDSocketAdapter())
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# Raw meta-data as text
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md_route = "{route}/meta-data".format(route=version_url)
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response = session.get(md_route)
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LOG.debug("[GET] [HTTP:%d] %s", response.status_code, md_route)
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if not response.ok:
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raise sources.InvalidMetaDataException(
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"Invalid HTTP response [{code}] from {route}: {resp}".format(
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code=response.status_code,
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route=md_route,
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resp=response.txt
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)
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)
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md["meta-data"] = response.text
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if metadata_only:
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return md # Skip network-data, vendor-data, user-data
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config_url = version_url + "config"
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# Represent all advertized/available config routes under
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# the dict path {LXD_SOCKET_API_VERSION: {config: {...}}.
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LOG.debug("[GET] %s", config_url)
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config_routes = session.get(config_url).json()
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md[LXD_SOCKET_API_VERSION] = {
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"config": {},
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"meta-data": md["meta-data"]
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}
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for config_route in config_routes:
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url = "http://lxd{route}".format(route=config_route)
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LOG.debug("[GET] %s", url)
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response = session.get(url)
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if response.ok:
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cfg_key = config_route.rpartition("/")[-1]
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# Leave raw data values/format unchanged to represent it in
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# instance-data.json for cloud-init query or jinja template
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# use.
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md[LXD_SOCKET_API_VERSION]["config"][cfg_key] = response.text
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# Promote common CONFIG_KEY_ALIASES to top-level keys.
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if cfg_key in CONFIG_KEY_ALIASES:
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md[CONFIG_KEY_ALIASES[cfg_key]] = response.text
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else:
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LOG.debug("Skipping %s on invalid response", url)
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return md
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# Used to match classes to dependencies
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datasources = [
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(DataSourceLXD, (sources.DEP_FILESYSTEM,)),
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]
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# Return a list of data sources that match this set of dependencies
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def get_datasource_list(depends):
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return sources.list_from_depends(depends, datasources)
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if __name__ == "__main__":
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import argparse
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description = """Query LXD metadata and emit a JSON object."""
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parser = argparse.ArgumentParser(description=description)
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parser.parse_args()
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print(util.json_dumps(read_metadata()))
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# vi: ts=4 expandtab

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