warewulf/install-recipe-vm.md

Configure libvirt and kvm to act as a Master System and Compute Node

This document is a companion to the primary install recipe document. It provides details on how to configure libvirt and kvm to act as a Master System and a Compute Node. If you follow these directions, you should have two systems that can be used to continue the primary install recipe document.

Install libvirt

The virtualization host will have SLES 15 installed and will be using kvm for the virtual machine manager. Using a fresh install of SLES 15, install the following packages:

• libvirt-client
• libvirt-daemon-qemu

sudo zypper install libvirt-client libvirt-daemon-qemu

After the packages are installed, grant an unprivileged user permission to libvirt and kvm functionality. Replace in the following command with the id of the user that will be creating the virtual machines.

sudo usermod -a -G kvm,libvirt <userid>

For the operating user, add the following environment variable to the users .profile configuration file.

export LIBVIRT_DEFAULT_URI=qemu:///system

The alternative to setting the LIBVIRT_DEFAULT_URI environment variable is to add the --connect=qemu:///system option to all executions of the libvirt shell virsh.

After changing these user settings, the user will need to log out and log back in for the settings to be effective.

Setup of libvirt networks

Two networks will be running in libvirt for this setup.

• The default network will provide the outbound connection for the master warewulf system.
• The internal network will be isolated from any external networks and will be used between the master and compute nodes for DHCP and PXE interactions.

Start and enable autostart for the default network

The default network is not enabled by default. The following commands will enable the network now, and cause it to start automatically in the future.

virsh net-start default
virsh net-autostart default

Add static address for master (optional)

Creating a static address for the master node on the default network will make it possible to log into the master node without having to "guess" the address. The address can be added to the virtualization hosts /etc/hosts configuration file for convienience.

Edit the default network by executing the command virsh net-edit default and add the host element. The XML should look like this:

<network>
  <name>default</name>
  <uuid>5884536d-64fd-4d56-b677-b85b450b1369</uuid>
  <forward mode='nat'/>
  <bridge name='virbr0' stp='on' delay='0'/>
  <mac address='52:54:00:e6:e9:13'/>
  <ip address='192.168.122.1' netmask='255.255.255.0'>
    <dhcp>
      <range start='192.168.122.2' end='192.168.122.254'/>
      <host mac='12:34:56:78:90:01' name='master' ip='192.168.122.2'/>
    </dhcp>
  </ip>
</network>

Create, start, and enable autostart for the internal network

The internal network is just a bridge between VMs and will have no packet forwarding or DHCP functionality. To create the internal network, you will need to create an XML file (named internal.xml for this example) with the following:

<network>
  <name>internal</name>
</network>

This file will be used to define the internal network within libvirt. The internal network will also need to be set to autostart and be started:

virsh net-define internal.xml
virsh net-autostart internal
virsh net-start internal

If all has gone well, you should be able to see the following after running the command virsh net-list:

 Name                 State      Autostart     Persistent
----------------------------------------------------------
 default              active     yes           yes
 internal             active     yes           yes

Setup of libvirt VMs

This installation will have two VMs defined, a master system and a compute node. The master system will be installed with openSUSE Tumbleweed, and the compute node will simply be cloned from the master node and modified.

The master system can be installed with openSUSE Tumbleweed distribution with the following command:

virt-install --location http://download.opensuse.org/tumbleweed/repo/oss/ --extra-args="console=ttyS0,115200" --name master --memory 4096 --virt-type kvm --disk size=20 --graphics none --network="network=default,mac=12:34:56:78:90:01" --network="network=internal,model=rtl8139,mac=12:34:56:78:91:00"

After the install is complete, log in to the node long enough to shut down the virtual machine using shutdown now at the command line.

Install tips

• Disable causing the swap file size the same as the memory size. This is unnecessarily wasted virtual disk space.
• Skip the creation of a system user. All work done on the master system will be done using the root user, and the compute node will not use the configured user.
• Disable the firewall.
• Enable the SSH server.

Cloning and editing the compute node

With the master system created and shut down, the compute node can be cloned from the master system by using the following command:

virt-clone --auto-clone -o master -n compute

A few changes need to be made to the compute node. Edit the node by executing virsh edit compute and make the following changes:

• Set the node to boot to network. Within /domain/os/boot, make sure dev is set to network, like this:

<boot dev='network'/>

• Remove the interface section for the network device attached to the default network. The lines to remove look like this:

<interface type='network'>
  <mac address='52:54:00:63:6a:c3'/>
  <source network='default'/>
  <model type='virtio'/>
  <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/>
</interface>

• Edit the internal network interface to have an easy-to-use MAC address. For this example, use this:

<mac address='12:34:56:78:91:01'/>

• For a stateful node (as in this example), modify the disk to be a scsi device and remove the address element. The disk target should look like this:

<disk type='file' device='disk'>
  <driver name='qemu' type='qcow2'/>
  <source file='/var/lib/libvirt/images/compute.qcow2'/>
  <target dev='sda' bus='scsi'/>
  <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0'/>
</disk>

• If a purely stateless node is necessary, then the disk section can be removed. Do not remove the disk section if you intend to create a stateful node:

Boot to the Master System

Now it is time to install the warewulf packages. Start the master system and, after startup has completed, login to the mode.

virsh start master
ssh root@192.168.122.2