In order to deploy a VM host in your MAAS network, you first need to set up a bridge to connect between your VM host and MAAS itself. This article explains:
- How to set up a VM host bridge with the web UI
- How to set up a VM host bridge with netplan
- How do set up a VM host bridge with libvirt
- How to set up SSH for use by libvirt
- How to make LXD available for hosting?
LXD sets up a bridge as part of the initialisation process; note that you will have to perform a couple of additional steps to prevent LXD from offering DHCP, which will interfere with the normal operation of MAAS. Everything you need to know is described at the initialisation link.
To enable VM host networking features, MAAS must match the VM host IP address of a potential VM host with a known device (a machine or controller). For example, if a machine not known to MAAS is set up as a VM host, enhanced interface selection features will not be available.
Itâs essential to enforce usage of IP addresses to avoid domain name conflicts, should different controllers resolve the same domain name with different IP addresses. You should also avoid using 127.0.0.1 when running multiple controllers, as it would confuse MAAS.
How to set up VM host bridge with MAAS UI
You can use the MAAS UI to configure a bridge to connect a VM host to MAAS:
Select the machine you want to use as a VM host, switch to the âNetworkâ tab. Select the network where you want to create the bridge and click âCreate bridge:â
Configure the bridge on a subnet MAAS controls. You may use any IP mode for the bridge:
When youâre done, it should look something like this:
Then you can deploy Ubuntu.
How to use netplan to configure a bridge
You can also use netplan to configure a VM host bridge:
Open your netplan configuration file. This should be in /etc/netplan. It could be called 50-cloud-init.yaml, netplan.yaml, or something else. Modify the file to add a bridge, using the example below to guide you:
network:
bridges:
br0:
addresses:
- 10.0.0.101/24
gateway4: 10.0.0.1
interfaces:
- enp1s0
macaddress: 52:54:00:39:9d:f9
mtu: 1500
nameservers:
addresses:
- 10.0.0.2
search:
- maas
parameters:
forward-delay: 15
stp: false
ethernets:
enp1s0:
match:
macaddress: 52:54:00:39:9d:f9
mtu: 1500
set-name: enp1s0
enp2s0:
match:
macaddress: 52:54:00:df:87:ac
mtu: 1500
set-name: enp2s0
enp3s0:
match:
macaddress: 52:54:00:a7:ac:46
mtu: 1500
set-name: enp3s0
version: 2
Apply the new configuration with netplan apply.
How to use libvirt to configure a bridge
It is also possible to use libvirt to configure a virtual bridge. This method will also work for LXD VM hosts running on Ubuntu. Be aware that other methods may be required if you are configuring LXD on an OS other than Ubuntu.
By default, libvirt creates a virtual bridge, virbr0, through which VMs communicate with each other and the Internet. DHCP, supplied by libvirt, automatically assigns an IP address to each VM. However, to enable network booting in MAAS, youâll need to provide DHCP in MAAS and either:
- Disable DHCP on libvirtâs
defaultnetwork, or - Create a new libvirt network
maaswith DHCP disabled.
You can set up such a maas network like this:
cat << EOF > maas.xml
<network>
<name>maas</name>
<forward mode='nat'>
<nat>
<port start='1024' end='65535'/>
</nat>
</forward>
<dns enable="no" />
<bridge name='virbr1' stp='off' delay='0'/>
<domain name='testnet'/>
<ip address='172.16.99.1' netmask='255.255.255.0'>
</ip>
</network>
EOF
virsh net-define maas.xml
Note that this network also has NAT port forwarding enabled to allow VMs to communicate with the Internet at large. Port forwarding is very useful in test environments.
How to set up SSH
For MAAS to successfully communicate with libvirt on your VM host machine â whether youâre running from snap or package, or running rack controllers in LXD containers or on localhost â this example command must succeed from every rack controller:
virsh -c qemu+ssh://$USER@$VM_HOST_IP/system list --all
Here, $USER is a user on your VM host who is a member of the libvirtd Unix group on the VM host, and $VM_HOST_IP is the IP of your VM host. Note that insufficient permissions for $USER may cause the virsh command to fail with an error such as failed to connect to the hypervisor. Check the $USER group membership to make sure $USER is a member of the libvirtd group.
How to set up SSH (libvirt only)
If you installed MAAS via snap, then create the needed SSH keys this way:
sudo mkdir -p /var/snap/maas/current/root/.ssh
cd /var/snap/maas/current/root/.ssh
sudo ssh-keygen -f id_rsa
Finally, youâll need to add id_rsa.pub to the authorized_keys file in /home/<vm-host-user-homedir-name>/.ssh/, where <vm-host-user-homedir-name> is the name of your VM host user.
How to make LXD available for VM hosting
Assuming that you want to use LXD VM hosts, you need to install the correct version of LXD. Prior to the release of Ubuntu 20.04 LXD was installed using Debian packages. The Debian packaged version of LXD is too old to use with MAAS. If this is the case, youâll need to remove the LXD Debian packages and install the Snap version. Note that you cannot install both Debian and snap versions, as this creates a conflict.
How to remove older versions of LXD
If youâre on a version of Ubuntu older than 20.04, or you have the Debian version of LXD, start the uninstall process with the following command:
sudo apt-get purge -y *lxd* *lxc*
This command should result in output that looks something like this:
Reading package lists... Done
Building dependency tree
Reading state information... Done
Note, selecting 'lxde-core' for glob '*lxd*'
Note, selecting 'python-pylxd-doc' for glob '*lxd*'
Note, selecting 'python3-pylxd' for glob '*lxd*'
Note, selecting 'python-nova-lxd' for glob '*lxd*'
Note, selecting 'lxde-common' for glob '*lxd*'
Note, selecting 'lxde-icon-theme' for glob '*lxd*'
Note, selecting 'lxde-settings-daemon' for glob '*lxd*'
Note, selecting 'lxde' for glob '*lxd*'
Note, selecting 'lxdm' for glob '*lxd*'
Note, selecting 'lxd' for glob '*lxd*'
Note, selecting 'lxd-tools' for glob '*lxd*'
Note, selecting 'python-pylxd' for glob '*lxd*'
Note, selecting 'lxdm-dbg' for glob '*lxd*'
Note, selecting 'lxde-session' for glob '*lxd*'
Note, selecting 'nova-compute-lxd' for glob '*lxd*'
Note, selecting 'openbox-lxde-session' for glob '*lxd*'
Note, selecting 'python-nova.lxd' for glob '*lxd*'
Note, selecting 'lxd-client' for glob '*lxd*'
Note, selecting 'openbox-lxde-session' instead of 'lxde-session'
Note, selecting 'lxctl' for glob '*lxc*'
Note, selecting 'lxc-common' for glob '*lxc*'
Note, selecting 'python3-lxc' for glob '*lxc*'
Note, selecting 'libclxclient-dev' for glob '*lxc*'
Note, selecting 'lxc-templates' for glob '*lxc*'
Note, selecting 'lxc1' for glob '*lxc*'
Note, selecting 'lxc-dev' for glob '*lxc*'
Note, selecting 'lxc' for glob '*lxc*'
Note, selecting 'liblxc1' for glob '*lxc*'
Note, selecting 'lxc-utils' for glob '*lxc*'
Note, selecting 'vagrant-lxc' for glob '*lxc*'
Note, selecting 'libclxclient3' for glob '*lxc*'
Note, selecting 'liblxc-dev' for glob '*lxc*'
Note, selecting 'nova-compute-lxc' for glob '*lxc*'
Note, selecting 'python-lxc' for glob '*lxc*'
Note, selecting 'liblxc-common' for glob '*lxc*'
Note, selecting 'golang-gopkg-lxc-go-lxc.v2-dev' for glob '*lxc*'
Note, selecting 'lxcfs' for glob '*lxc*'
Note, selecting 'liblxc-common' instead of 'lxc-common'
Package 'golang-gopkg-lxc-go-lxc.v2-dev' is not installed, so not removed
Package 'libclxclient-dev' is not installed, so not removed
Package 'libclxclient3' is not installed, so not removed
Package 'lxc-templates' is not installed, so not removed
Package 'lxctl' is not installed, so not removed
Package 'lxde' is not installed, so not removed
Package 'lxde-common' is not installed, so not removed
Package 'lxde-core' is not installed, so not removed
Package 'lxde-icon-theme' is not installed, so not removed
Package 'lxde-settings-daemon' is not installed, so not removed
Package 'lxdm' is not installed, so not removed
Package 'lxdm-dbg' is not installed, so not removed
Package 'openbox-lxde-session' is not installed, so not removed
Package 'python-lxc' is not installed, so not removed
Package 'python3-lxc' is not installed, so not removed
Package 'vagrant-lxc' is not installed, so not removed
Package 'liblxc-dev' is not installed, so not removed
Package 'lxc-dev' is not installed, so not removed
Package 'nova-compute-lxc' is not installed, so not removed
Package 'nova-compute-lxd' is not installed, so not removed
Package 'python-nova-lxd' is not installed, so not removed
Package 'python-pylxd' is not installed, so not removed
Package 'python-pylxd-doc' is not installed, so not removed
Package 'lxc' is not installed, so not removed
Package 'lxc-utils' is not installed, so not removed
Package 'lxc1' is not installed, so not removed
Package 'lxd-tools' is not installed, so not removed
Package 'python-nova.lxd' is not installed, so not removed
Package 'python3-pylxd' is not installed, so not removed
The following packages were automatically installed and are no longer required:
dns-root-data dnsmasq-base ebtables libuv1 uidmap xdelta3
Use 'sudo apt autoremove' to remove them.
The following packages will be REMOVED:
liblxc-common* liblxc1* lxcfs* lxd* lxd-client*
0 upgraded, 0 newly installed, 5 to remove and 21 not upgraded.
pAfter this operation, 34.1 MB disk space will be freed.
(Reading database ... 67032 files and directories currently installed.)
Removing lxd (3.0.3-0ubuntu1~18.04.1) ...
Removing lxd dnsmasq configuration
Removing lxcfs (3.0.3-0ubuntu1~18.04.2) ...
Removing lxd-client (3.0.3-0ubuntu1~18.04.1) ...
Removing liblxc-common (3.0.3-0ubuntu1~18.04.1) ...
Removing liblxc1 (3.0.3-0ubuntu1~18.04.1) ...
Processing triggers for man-db (2.8.3-2ubuntu0.1) ...
Processing triggers for libc-bin (2.27-3ubuntu1) ...
(Reading database ... 66786 files and directories currently installed.)
Purging configuration files for liblxc-common (3.0.3-0ubuntu1~18.04.1) ...
Purging configuration files for lxd (3.0.3-0ubuntu1~18.04.1) ...
Purging configuration files for lxcfs (3.0.3-0ubuntu1~18.04.2) ...
Processing triggers for systemd (237-3ubuntu10.40) ...
Processing triggers for ureadahead (0.100.0-21) ...
You should also autoremove packages no longer needed by LXD:
$ sudo apt-get autoremove -y
Output from this command should be similar to:
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages will be REMOVED:
dns-root-data dnsmasq-base ebtables libuv1 uidmap xdelta3
0 upgraded, 0 newly installed, 6 to remove and 21 not upgraded.
After this operation, 1860 kB disk space will be freed.
(Reading database ... 66769 files and directories currently installed.)
Removing dns-root-data (2018013001) ...
Removing dnsmasq-base (2.79-1) ...
Removing ebtables (2.0.10.4-3.5ubuntu2.18.04.3) ...
Removing libuv1:amd64 (1.18.0-3) ...
Removing uidmap (1:4.5-1ubuntu2) ...
Removing xdelta3 (3.0.11-dfsg-1ubuntu1) ...
Processing triggers for man-db (2.8.3-2ubuntu0.1) ...
Processing triggers for libc-bin (2.27-3ubuntu1) ...
Now install LXD from the Snap:
$ sudo snap install lxd
2020-05-20T22:02:57Z INFO Waiting for restart...
lxd 4.1 from Canonicalâ installed
R\How to refresh LXD on 20.04
If you are on 20.04 or above LXD should be installed by default, but itâs a good idea to make sure itâs up to date:
$ sudo snap refresh
All snaps up to date.
How to initialise LXD prior to use
Once LXD is installed it needs to be configured with lxd init before first use:
$ sudo lxd init
Your interactive output should look something like the following. Note a few points important points about these questions:
-
Would you like to use LXD clustering? (yes/no) [default=no]: no- MAAS does not currently support LXD clusters. -
Name of the storage back-end to use (btrfs, dir, lvm, zfs, ceph) [default=zfs]: dir- testing has primarily been with dir; other options should work, but less testing has been done, so use at your own risk. -
Would you like to connect to a MAAS server? (yes/no) [default=no]: no- When LXD is connected to MAAS containers or virtual machines created by LXD will be automatically added to MAAS as devices. This feature should work, but has limited testing thus far. -
Would you like to configure LXD to use an existing bridge or host interface? (yes/no) [default=no]: yes- The bridge LXD creates is isolated and not managed by MAAS. If this bridge is used, you would be able to add the LXD VM host and compose virtual machines, but commissioning, deploying, and any other MAAS action which uses the network will fail â soyesis the correct answer here. -
Name of the existing bridge or host interface: br0- br0 is the name of the bridge the user configured (see sections above) which is connected to a MAAS-managed network. -
Trust password for new clients:- This is the password the user will enter when connecting with MAAS.
Would you like to use LXD clustering? (yes/no) [default=no]: no
Do you want to configure a new storage pool? (yes/no) [default=yes]: yes
Name of the new storage pool [default=default]:
Name of the storage back-end to use (btrfs, dir, lvm, zfs, ceph) [default=zfs]: dir
Would you like to connect to a MAAS server? (yes/no) [default=no]: no
Would you like to create a new local network bridge? (yes/no) [default=yes]: no
Would you like to configure LXD to use an existing bridge or host interface? (yes/no) [default=no]: yes
Name of the existing bridge or host interface: br0
Would you like LXD to be available over the network? (yes/no) [default=no]: yes
pAddress to bind LXD to (not including port) [default=all]:
Port to bind LXD to [default=8443]:
Trust password for new clients:
Again:
Would you like stale cached images to be updated automatically? (yes/no) [default=yes]
Would you like a YAML "lxd init" preseed to be printed? (yes/no) [default=no]:
After initialising LXD, you will also want to make sure that LXD is not trying to provide DHCP for the new local network bridge. You can check this with the following command:
lxc network show lxdbr0
If you didnât accept the default bridge name (lxdbr0), substitute your name for that new bridge in the command above. This will produce output something like this:
config:
dns.mode: managed
ipv4.address: 10.146.214.1/24
ipv4.dhcp: "true"
ipv4.nat: "true"
ipv6.address: fd42:c560:ee59:bb2::1/64
ipv6.dhcp: "true"
ipv6.nat: "true"
description: ""
name: lxdbr0
type: bridge
used_by:
- /1.0/profiles/default
managed: true
status: Created
locations:
- none
There is a quick tutorial on the possible settings here. For simplicity, to turn off LXD-provided DHCP, you need to change three settings, as follows:
lxc network set lxdbr0 dns.mode=none
lxc network set lxdbr0 ipv4.dhcp=false
lxc network set lxdbr0 ipv6.dhcp=false
You can check your work by repeating the show command:
$ lxc network show lxdbr0
config:
dns.mode: none
ipv4.address: 10.146.214.1/24
ipv4.dhcp: "false"
ipv4.nat: "true"
ipv6.address: fd42:c560:ee59:bb2::1/64
ipv6.dhcp: "false"
ipv6.nat: "true"
description: ""
name: lxdbr0
type: bridge
used_by:
- /1.0/profiles/default
managed: true
status: Created
locations:
- none
Once thatâs done, the LXD host is now ready to be added to MAAS as an LXD VM host. Upon adding the VM host, its own commissioning information will be refreshed.
When composing a virtual machine with LXD, MAAS uses either the âmaasâ LXD profile, or (if that doesnât exist) the âdefaultâ LXD profile. The profile is used to determine which bridge to use. Users may also add additional LXD options to the profile which are not yet supported in MAAS.
