Add LXD datasource (#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

1 files changed, 8 insertions, 1 deletions

diff --git a/tests/integration_tests/clouds.py b/tests/integration_tests/clouds.py
index 32fdc91e..dee2adff 100644
--- a/tests/integration_tests/clouds.py
+++ b/tests/integration_tests/clouds.py
@@ -1,7 +1,10 @@
 # This file is part of cloud-init. See LICENSE file for license information.
 from abc import ABC, abstractmethod
+import datetime
 import logging
 import os.path
+import random
+import string
 from uuid import UUID
 
 from pycloudlib import (
@@ -309,8 +312,12 @@ class _LxdIntegrationCloud(IntegrationCloud):
         except KeyError:
             profile_list = self._get_or_set_profile_list(release)
 
+        prefix = datetime.datetime.utcnow().strftime("cloudinit-%m%d-%H%M%S")
+        default_name = prefix + "".join(
+            random.choices(string.ascii_lowercase + string.digits, k=8)
+        )
         pycloudlib_instance = self.cloud_instance.init(
-            launch_kwargs.pop('name', None),
+            launch_kwargs.pop('name', default_name),
             release,
             profile_list=profile_list,
             **launch_kwargs