9.18.5. Configuring PXE booting for virtual machines

Procedure

1. Configure a PXE network on the cluster:

   1. Create the network attachment definition file for PXE network pxe-net-conf:

      apiVersion: "k8s.cni.cncf.io/v1"
      kind: NetworkAttachmentDefinition
      metadata:
        name: pxe-net-conf
      spec:
        config: |
          {
            "cniVersion": "0.3.1",
            "name": "pxe-net-conf",
            "type": "bridge",
            "bridge": "bridge-interface",
            "macspoofchk": false,
            "vlan": 100,
            "disableContainerInterface": true,
            "preserveDefaultVlan": false
          }

      • metadata.name specifies the name for the NetworkAttachmentDefinition object.
      • spec.config.name specifies the name for the configuration. It is recommended to match the configuration name to the name value of the network attachment definition.
      • spec.config.type specifies the actual name of the Container Network Interface (CNI) plugin that provides the network for this network attachment definition. This example uses a Linux bridge CNI plugin. You can also use an OVN-Kubernetes localnet or an SR-IOV CNI plugin.
      • spec.config.bridge specifies the name of the Linux bridge configured on the node.
      • spec.config.macspoofchk is an optional flag to enable the MAC spoof check. When set to true, you cannot change the MAC address of the pod or guest interface. This attribute allows only a single MAC address to exit the pod, which provides security against a MAC spoofing attack.
      • spec.config.vlan is an optional VLAN tag. No additional VLAN configuration is required on the node network configuration policy.
      • spec.config.preserveDefaultVlan is an optional flag that indicates whether the VM connects to the bridge through the default VLAN. The default value is true.

2. Create the network attachment definition by using the file you created in the previous step:

   $ oc create -f pxe-net-conf.yaml

3. Edit the virtual machine instance configuration file to include the details of the interface and network.

   1. Specify the network and MAC address, if required by the PXE server. If the MAC address is not specified, a value is assigned automatically.

      Ensure that bootOrder is set to 1 so that the interface boots first. In this example, the interface is connected to a network called <pxe-net>:

      interfaces:
      - masquerade: {}
        name: default
      - bridge: {}
        name: pxe-net
        macAddress: de:00:00:00:00:de
        bootOrder: 1

      참고

      Boot order is global for interfaces and disks.

   2. Assign a boot device number to the disk to ensure proper booting after operating system provisioning.

      Set the disk bootOrder value to 2:

      devices:
        disks:
        - disk:
            bus: virtio
          name: containerdisk
          bootOrder: 2

   3. Specify that the network is connected to the previously created network attachment definition. In this scenario, <pxe-net> is connected to the network attachment definition called <pxe-net-conf>:

      networks:
      - name: default
        pod: {}
      - name: pxe-net
        multus:
          networkName: pxe-net-conf

4. Create the virtual machine instance:

   $ oc create -f vmi-pxe-boot.yaml

   Example output:

     virtualmachineinstance.kubevirt.io "vmi-pxe-boot" created

5. Wait for the virtual machine instance to run:

   $ oc get vmi vmi-pxe-boot -o yaml | grep -i phase
     phase: Running

6. View the virtual machine instance using VNC:

   $ virtctl vnc vmi-pxe-boot

7. Watch the boot screen to verify that the PXE boot is successful.

8. Log in to the virtual machine instance:

   $ virtctl console vmi-pxe-boot

Verification

1. Verify the interfaces and MAC address on the virtual machine and that the interface connected to the bridge has the specified MAC address. In this case, we used eth1 for the PXE boot, without an IP address. The other interface, eth0, got an IP address from OpenShift Container Platform.

   $ ip addr

   Example output:

   ...
   3. eth1: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN group default qlen 1000
      link/ether de:00:00:00:00:de brd ff:ff:ff:ff:ff:ff