#はじめに
この記事は、OpenStack Advent Calendar 2016の12/14分の記事になります.
Canonicalの鈴木です、OpenStackのComputeノードをLXDで用意する機会がありましたので
簡易ですがご紹介したいと思います.

#物理環境
CanonicalのOrangeBoxを利用しています。

[OpenStackノード]
Nodes: Controller 1台、Neutron GW 1台、Compute3台
OS: Ubuntu16.04 xenial

#OpenStackの用意
Jujuを利用してOpenStack LXD Bundle Charmを利用してデプロイ.
OpenStack LXD Bundle Charm: https://jujucharms.com/u/openstack-charmers-next/openstack-lxd

ubuntu@OrangeBox64:~$ juju status
Model    Controller  Cloud/Region  Version
default  maas        maas          2.0.1

App                    Version      Status   Scale  Charm                  Store       Rev  OS      Notes
glance                 13.0.0       active       1  glance                 jujucharms  253  ubuntu  
keystone               10.0.0       active       1  keystone               jujucharms  258  ubuntu  
lxd                    2.0.5        active       3  lxd                    jujucharms    4  ubuntu  
mysql                  5.6.21-25.8  active       1  percona-cluster        jujucharms  246  ubuntu  
neutron-api            9.0.0        active       1  neutron-api            jujucharms  246  ubuntu  
neutron-gateway        9.0.0        active       1  neutron-gateway        jujucharms  232  ubuntu  
neutron-openvswitch    9.0.0        active       3  neutron-openvswitch    jujucharms  238  ubuntu  
nova-cloud-controller  14.0.1       active       1  nova-cloud-controller  jujucharms  292  ubuntu  
nova-compute           14.0.1       active       3  nova-compute           jujucharms  259  ubuntu  
ntp                                 unknown      4  ntp                    jujucharms    0  ubuntu  
openstack-dashboard    10.0.0       active       1  openstack-dashboard    jujucharms  243  ubuntu  
rabbitmq-server        3.5.7        active       1  rabbitmq-server        jujucharms   54  ubuntu  

Unit                      Workload  Agent  Machine  Public address  Ports           Message
glance/0*                 active    idle   23       172.27.64.5     9292/tcp        Unit is ready
keystone/0*               active    idle   23       172.27.64.5     5000/tcp        Unit is ready
mysql/0*                  active    idle   21       172.27.64.3                     Unit is ready
neutron-api/0*            active    idle   23       172.27.64.5     9696/tcp        Unit is ready
neutron-gateway/0*        active    idle   26       172.27.64.7                     Unit is ready
  ntp/3                   unknown   idle            172.27.64.7                     
nova-cloud-controller/0*  active    idle   23       172.27.64.5     8774/tcp        Unit is ready
nova-compute/0            active    idle   25       172.27.64.8                     Unit is ready
  lxd/1                   active    idle            172.27.64.8                     Unit is ready
  neutron-openvswitch/1   active    idle            172.27.64.8                     Unit is ready
  ntp/1                   unknown   idle            172.27.64.8                     
nova-compute/1*           active    idle   22       172.27.64.4                     Unit is ready
  lxd/0*                  active    idle            172.27.64.4                     Unit is ready
  neutron-openvswitch/0*  active    idle            172.27.64.4                     Unit is ready
  ntp/0*                  unknown   idle            172.27.64.4                     
nova-compute/2            active    idle   24       172.27.64.6                     Unit is ready
  lxd/2                   active    idle            172.27.64.6                     Unit is ready
  neutron-openvswitch/2   active    idle            172.27.64.6                     Unit is ready
  ntp/2                   unknown   idle            172.27.64.6                     
openstack-dashboard/0*    active    idle   23       172.27.64.5     80/tcp,443/tcp  Unit is ready
rabbitmq-server/0*        active    idle   23       172.27.64.5     5672/tcp        Unit is ready

Machine   State    DNS           Inst id               Series  AZ
21        started  172.27.64.3   4y3hgt                xenial  zone0
22        started  172.27.64.4   4y3hfm                xenial  zone1
22/lxd/0  started  172.27.65.27  juju-79fcc7-22-lxd-0  xenial  
22/lxd/1  started  172.27.64.10  juju-79fcc7-22-lxd-1  xenial  
22/lxd/2  started  172.27.65.25  juju-79fcc7-22-lxd-2  xenial  
23        started  172.27.64.5   4y3hfs                xenial  zone2
23/lxd/0  started  172.27.64.9   juju-79fcc7-23-lxd-0  xenial  
23/lxd/1  started  172.27.65.23  juju-79fcc7-23-lxd-1  xenial  
23/lxd/2  started  172.27.65.24  juju-79fcc7-23-lxd-2  xenial  
24        started  172.27.64.6   4y3hgr                xenial  zone0
24/lxd/0  started  172.27.65.22  juju-79fcc7-24-lxd-0  xenial  
24/lxd/1  started  172.27.65.28  juju-79fcc7-24-lxd-1  xenial  
24/lxd/2  started  172.27.65.29  juju-79fcc7-24-lxd-2  xenial  
25        started  172.27.64.8   4y3hft                xenial  zone2
25/lxd/0  started  172.27.65.21  juju-79fcc7-25-lxd-0  xenial  
25/lxd/1  started  172.27.65.26  juju-79fcc7-25-lxd-1  xenial  
26        started  172.27.64.7   4y3hfn                xenial  zone1

Relation                 Provides               Consumes               Type
cluster                  glance                 glance                 peer
identity-service         glance                 keystone               regular
shared-db                glance                 mysql                  regular
image-service            glance                 nova-cloud-controller  regular
image-service            glance                 nova-compute           regular
amqp                     glance                 rabbitmq-server        regular
cluster                  keystone               keystone               peer
shared-db                keystone               mysql                  regular
identity-service         keystone               neutron-api            regular
identity-service         keystone               nova-cloud-controller  regular
identity-service         keystone               openstack-dashboard    regular
lxd-migration            lxd                    lxd                    peer
lxd                      lxd                    nova-compute           regular
cluster                  mysql                  mysql                  peer
shared-db                mysql                  neutron-api            regular
shared-db                mysql                  nova-cloud-controller  regular
cluster                  neutron-api            neutron-api            peer
neutron-plugin-api       neutron-api            neutron-gateway        regular
neutron-plugin-api       neutron-api            neutron-openvswitch    regular
neutron-api              neutron-api            nova-cloud-controller  regular
amqp                     neutron-api            rabbitmq-server        regular
cluster                  neutron-gateway        neutron-gateway        peer
quantum-network-service  neutron-gateway        nova-cloud-controller  regular
juju-info                neutron-gateway        ntp                    subordinate
amqp                     neutron-gateway        rabbitmq-server        regular
neutron-plugin           neutron-openvswitch    nova-compute           regular
amqp                     neutron-openvswitch    rabbitmq-server        regular
cluster                  nova-cloud-controller  nova-cloud-controller  peer
cloud-compute            nova-cloud-controller  nova-compute           regular
amqp                     nova-cloud-controller  rabbitmq-server        regular
lxd                      nova-compute           lxd                    subordinate
neutron-plugin           nova-compute           neutron-openvswitch    subordinate
compute-peer             nova-compute           nova-compute           peer
juju-info                nova-compute           ntp                    subordinate
amqp                     nova-compute           rabbitmq-server        regular
ntp-peers                ntp                    ntp                    peer
cluster                  openstack-dashboard    openstack-dashboard    peer
cluster                  rabbitmq-server        rabbitmq-server        peer

#ComputeノードLXDパラメータ

nova.conf

[DEFAULT]
verbose=True
debug=True
dhcpbridge_flagfile=/etc/nova/nova.conf
dhcpbridge=/usr/bin/nova-dhcpbridge
logdir=/var/log/nova
state_path=/var/lib/nova
force_dhcp_release=True
use_syslog = False
ec2_private_dns_show_ip=True
api_paste_config=/etc/nova/api-paste.ini
enabled_apis=osapi_compute,metadata
auth_strategy=keystone
my_ip = 172.27.64.8

vnc_enabled = False
novnc_enabled = False
libvirt_vif_driver = nova.virt.libvirt.vif.LibvirtGenericVIFDriver
security_group_api = neutron
firewall_driver = nova.virt.firewall.NoopFirewallDriver
network_api_class = nova.network.neutronv2.api.API
use_neutron = True
volume_api_class = nova.volume.cinder.API
reserved_host_memory = 512



[neutron]
url = http://172.27.64.5:9696
auth_url = http://172.27.64.5:35357
auth_type = password
project_domain_name = default
user_domain_name = default
project_name = services
username = nova
password = ptMFPHWVRBhyGrXqhxhPwwtmKbZwcXXwHkxTVkGbrr9FXSxZmCghYLb7VwHh7KNC
signing_dir = 
[keystone_authtoken]
auth_uri = http://172.27.64.5:5000
auth_url = http://172.27.64.5:35357
auth_type = password
project_domain_name = default
user_domain_name = default
project_name = services
username = nova
password = ptMFPHWVRBhyGrXqhxhPwwtmKbZwcXXwHkxTVkGbrr9FXSxZmCghYLb7VwHh7KNC
signing_dir = 


[glance]
api_servers = http://172.27.64.5:9292
[libvirt]
rbd_user = 
rbd_secret_uuid = 
live_migration_uri = qemu+ssh://%s/system

# Disable tunnelled migration so that selective
# live block migration can be supported.
live_migration_tunnelled = False



[oslo_messaging_rabbit]
rabbit_userid = nova
rabbit_virtual_host = openstack
rabbit_password = SK2CLycVLTYVYJmCkN6rhCYPjPrNdYGpNyxSShqY775WPJyJC458HVHrswzwZXYW
rabbit_host = 172.27.64.5


[cinder]

os_region_name = RegionOne



[oslo_concurrency]
lock_path=/var/lock/nova

[workarounds]
disable_libvirt_livesnapshot = False



[serial_console]
enabled = false
proxyclient_address = 172.27.64.8
base_url = ws://172.27.64.5:6083/

nova-compute.conf

[DEFAULT]
compute_driver = lxd.LXDDriver

compute_driverパラメータをlxd.LXDDriverに変更.

#パッケージバージョンとLXDの動作確認

root@node07ob64:~# dpkg -l | grep lxd
ii  lxd                                2.0.5-0ubuntu1~ubuntu16.04.1      amd64        Container hypervisor based on LXC - daemon
ii  lxd-client                         2.0.5-0ubuntu1~ubuntu16.04.1      amd64        Container hypervisor based on LXC - client
ii  nova-compute-lxd                   14.0.0-0ubuntu1~cloud0            all          Openstack Compute - LXD container hypervisor support
ii  python-nova-lxd                    14.0.0-0ubuntu1~cloud0            all          OpenStack Compute Python libraries - LXD driver
ii  python-pylxd                       2.1.1-0ubuntu1~cloud0             all          Python library for interacting with LXD REST API
root@node07ob64:~# lxc list
+----------------------+---------+----------------------+------+------------+-----------+
|         NAME         |  STATE  |         IPV4         | IPV6 |    TYPE    | SNAPSHOTS |
+----------------------+---------+----------------------+------+------------+-----------+
| juju-79fcc7-25-lxd-0 | RUNNING | 172.27.65.21 (eth0)  |      | PERSISTENT | 0         |
+----------------------+---------+----------------------+------+------------+-----------+
| juju-79fcc7-25-lxd-1 | RUNNING | 172.27.65.26 (eth0)  |      | PERSISTENT | 0         |
+----------------------+---------+----------------------+------+------------+-----------+

#Hypervisorの確認

ComputeノードがType "lxd"として認識されている.

#外部ネットワークとテナントネットワークを作成

#インスタンスを複数起動

#Nova LXDの動作概要
/usr/lib/python2.7/dist-packages/nova/virt/lxd/driver.pyを参照.

pylxdを利用してLXDをコントロール.
Glanceからイメージを取得してくる.
LXCコンテナ用のインターフェース作成.
LXCコンテナの作成.
LXCコンテナのスタート.

nova-compute.logからインタフェース作成コマンド抜粋

#インスタンス用LinuxBridgeの作成
sudo nova-rootwrap /etc/nova/rootwrap.conf brctl addbr qbr9e0c6af1-30 
sudo nova-rootwrap /etc/nova/rootwrap.conf brctl stp qbr9e0c6af1-30 off
sudo nova-rootwrap /etc/nova/rootwrap.conf tee /sys/class/net/qbr9e0c6af1-30/bridge/multicast_snooping
#インスタンス用のvethの作成
sudo nova-rootwrap /etc/nova/rootwrap.conf ip link add qvb9e0c6af1-30 type veth peer name qvo9e0c6af1-30 
sudo nova-rootwrap /etc/nova/rootwrap.conf ip link set qvb9e0c6af1-30 up
sudo nova-rootwrap /etc/nova/rootwrap.conf ip link set qvb9e0c6af1-30 promisc on
sudo nova-rootwrap /etc/nova/rootwrap.conf ip link set qvo9e0c6af1-30 up
sudo nova-rootwrap /etc/nova/rootwrap.conf ip link set qvo9e0c6af1-30 promisc on
sudo nova-rootwrap /etc/nova/rootwrap.conf ip link set qbr9e0c6af1-30 up
#vethをLinuxBridgeへ接続
sudo nova-rootwrap /etc/nova/rootwrap.conf brctl addif qbr9e0c6af1-30 qvb9e0c6af1-30
#vethをOVSのbr-intへ接続
sudo nova-rootwrap /etc/nova/rootwrap.conf ovs-vsctl --timeout=120 -- --if-exists del-port qvo9e0c6af1-30 -- add-port br-int qvo9e0c6af1-30 -- set Interface qvo9e0c6af1-30 external-ids:iface-id=9e0c6af1-30bc-418d-b82f-c025c935d987 external-ids:iface-status=active external-ids:attached-mac=fa:16:3e:e4:a3:bf external-ids:vm-uuid=instance-00000014

root@node07ob64:~# lxc list
+----------------------+---------+----------------------+------+------------+-----------+
|         NAME         |  STATE  |         IPV4         | IPV6 |    TYPE    | SNAPSHOTS |
+----------------------+---------+----------------------+------+------------+-----------+
| instance-00000002    | RUNNING | 192.168.20.4 (eth0)  |      | PERSISTENT | 0         |
+----------------------+---------+----------------------+------+------------+-----------+
| instance-0000000c    | RUNNING | 192.168.20.12 (eth0) |      | PERSISTENT | 0         |
+----------------------+---------+----------------------+------+------------+-----------+
| instance-00000012    | RUNNING | 192.168.20.7 (eth0)  |      | PERSISTENT | 0         |
+----------------------+---------+----------------------+------+------------+-----------+
| juju-79fcc7-25-lxd-0 | RUNNING | 172.27.65.21 (eth0)  |      | PERSISTENT | 0         |
+----------------------+---------+----------------------+------+------------+-----------+
| juju-79fcc7-25-lxd-1 | RUNNING | 172.27.65.26 (eth0)  |      | PERSISTENT | 0         |
+----------------------+---------+----------------------+------+------------+-----------+

novaからインスタンスを起動後にコンピュートノードにてlxc listをするとコンテナ一覧が見れます.

root@node07ob64:/usr/lib/python2.7/dist-packages/nova/api# lxc profile show instance-00000014
name: instance-00000014
config:
  boot.autostart: "True"
  limits.cpu: "1"
  limits.memory: 2048MB
  raw.lxc: |
    lxc.console.logfile=/var/log/lxd/instance-00000014/console.log
description: ""
devices:
  qbr9e0c6af1-30:
    host_name: tap9e0c6af1-30
    hwaddr: fa:16:3e:e4:a3:bf
    nictype: bridged
    parent: qbr9e0c6af1-30
    type: nic
  root:
    path: /
    size: 0GB
    type: disk

lxc profileコマンドで詳細を確認、nictypeは"bridged".

root@node07ob64:~# lxc exec instance-0000000c /bin/bash
root@lxc-test-1:~# ifconfig
eth0      Link encap:Ethernet  HWaddr fa:16:3e:54:f9:9d  
          inet addr:192.168.20.12  Bcast:192.168.20.255  Mask:255.255.255.0
          inet6 addr: fe80::f816:3eff:fe54:f99d/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1456  Metric:1
          RX packets:2711 errors:0 dropped:0 overruns:0 frame:0
          TX packets:1425 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:252983 (252.9 KB)  TX bytes:129955 (129.9 KB)

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:65536  Metric:1
          RX packets:4 errors:0 dropped:0 overruns:0 frame:0
          TX packets:4 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1 
          RX bytes:280 (280.0 B)  TX bytes:280 (280.0 B)

もちろんlxc execコマンドでコンテナにアクセスすることも可能です。

コンピュートノード間での簡易ネットワーク図.

ubuntu@OrangeBox64:~$ juju ssh 26
ubuntu@node02ob64:~$ sudo -s

root@node02ob64:~# ip netns
qdhcp-f8ec06d8-c199-45b8-bc72-56ee2c806fed (id: 3)
qdhcp-2ed6a3e2-9d78-4323-b6dd-d433e67d7f9f (id: 2)
qrouter-35fea0f3-ca4d-4bdf-a3b7-c00194bbd566 (id: 1)
qdhcp-ac7bafe8-3c37-48ba-8c24-98be14f4d9f7 (id: 0)

root@node02ob64:~# ip netns exec qrouter-35fea0f3-ca4d-4bdf-a3b7-c00194bbd566 bash

root@node02ob64:~# ping 119.115.26.136
PING 119.115.26.136 (119.115.26.136) 56(84) bytes of data.
64 bytes from 119.115.26.136: icmp_seq=1 ttl=64 time=0.816 ms
64 bytes from 119.115.26.136: icmp_seq=2 ttl=64 time=0.462 ms
64 bytes from 119.115.26.136: icmp_seq=3 ttl=64 time=0.383 ms
^C
--- 119.115.26.136 ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2000ms
rtt min/avg/max/mdev = 0.383/0.553/0.816/0.190 ms

root@node02ob64:~# ping 119.115.26.133
PING 119.115.26.133 (119.115.26.133) 56(84) bytes of data.
64 bytes from 119.115.26.133: icmp_seq=1 ttl=64 time=0.827 ms
64 bytes from 119.115.26.133: icmp_seq=2 ttl=64 time=0.369 ms
64 bytes from 119.115.26.133: icmp_seq=3 ttl=64 time=0.497 ms

ネットワークノードからインスタンスに付与した外部ネットワークやFloatingIPの接続も可能です.

#おわりに
通常はKVMをハイパーバイザーに使用されてることが多いのではないかと思います。NovaLXDを利用してLXCにすることでKVMに存在するオーバーヘッドを取り除いたりインスタンスの作成削除時間を短縮するできるのかなと考えます、NovaLXDはOpenStackの可能性を広めてくれる存在一つです.