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. Once that’s done, you can add and manage VM hosts – and subsequently, create VMs to act as MAAS machines. This article explains:
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.
NOTE: It’s 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 a VM host bridge with netplan
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 set up a VM host bridge with libvirt
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, you’ll need to provide DHCP in MAAS and either:
default network, ormaas with 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 use by libvirt
For MAAS to successfully communicate with libvirt on your VM host machine – whether you’re running from snap or package, or running rack controllers in LXD containers or on localhost – 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.
NOTE: MAAS will automatically discover and store the resources your VM host contains. Any existing machines will also appear on the ‘Machines’ page, and MAAS will automatically attempt to commission them.