Enable Platform9 DHCP

Recommended for KubVirt installations

Platform9 DHCP is the recommended DHCP (vs whereabouts ) for KubeVirt installations. When leveraging whereabouts there is an issue that occurs during Live Migrations where the Virtual Machine IP address will change when migrated to the target host.

What is Platform9 DHCP

Platform9 created an alternative to whereabouts for the KubeVirt use case by having a DHCP server running inside the pod/vm to cater to the DHCP requests from the virtual machine instance (not the pod in the case of Kubevirt). Multus net-attach-def will use the DHCP server, and there is no need to specify the IPAM plugin. The client/consumer VM will need the dhclient for sending DHCP requests.

Prerequisites

  • Kubevirt

  • Luigi (advanced Networking)

  • Kubemacpool

Enabling the Platform9 DHCP Addon:

  1. Using the Luigi addons, enable dhcpController addon

apiVersion: plumber.k8s.pf9.io/v1 kind: NetworkPlugins metadata: name: networkplugins-sample-nosriov spec: plugins: ... dhcpController: {}

  1. This creates the dhcp-controller-system namespace with the controller for the dnsmasq.

  2. Create NetworkAttachmentDefinition . Example:

apiVersion: plumber.k8s.pf9.io/v1 kind: HostNetworkTemplate metadata: name: ovs-br03-config spec: # Add fields here ovsConfig: - bridgeName: "ovs-br03" nodeInterface: "ens5" --- apiVersion: "k8s.cni.cncf.io/v1" kind: NetworkAttachmentDefinition metadata: name: ovs-dnsmasq-test-woipam annotations: k8s.v1.cni.cncf.io/resourceName: ovs-cni.network.kubevirt.io/ovs-br03 spec: config: '{ "cniVersion": "0.3.1", "type": "ovs", "name": "ovs-dnsmasq-test-woipam", "bridge": "ovs-br03" }'

  1. To use a image that does not have dhclient installed/ able to install, create an additional NetworkAttachmentDefinition with the dhcp plugin enabled and start the dhcp daemon.

  2. Create a DHCP Server

--- apiVersion: "k8s.cni.cncf.io/v1" kind: NetworkAttachmentDefinition metadata: name: ovs-dnsmasq-test annotations: k8s.v1.cni.cncf.io/resourceName: ovs-cni.network.kubevirt.io/ovs-br03 spec: config: '{ "cniVersion": "0.3.1", "type": "ovs", "name": "ovs-dnsmasq-test", "bridge": "ovs-br03", "ipam": { "type": "dhcp" } }'

  1. About the fields

a . Name: Name of the DHCPServer. Configurations of dnsmasq will be generated in a Configmap with the same name

b. networks: list of all networks that this pod will serve

  • networkName: Name of NetworkAttachmentDefinition. Should not have dhcp plugin enabled.

  • interfaceIp: IP address that the pod will be allocated. Must have prefix to ensure proper routes are added.

  • leaseDuration: Duration the leases offered should be valid for. Provide in valid formats for dnsmasq (eg: 10m, 5h, etc). Defaults to 1h

  • vlanId: Dnsmasq network identifier. Used as an identifier while restoring IPs.

  • cidr:range_start, range_end, gateway are optional. range is compulsory. If range start and end are provided, they will be used in place of the default start and end.

  1. A configmap is generated based on the DHCPServer. This is a conf file for dnsmasq. It can be overridden by creating a valid configmap with the same name as that of the DHCPServer.

Info

For any specific configurations, you can provide your own configmap. Create a configmap with valid dnsmasq.conf parameters. Along with this, dhcp-range must be in one of these two formats

  1. dhcp-range=<start_IP>,<end_ip>,<netmask>,<leasetime>

  2. dhcp-range=<vlanID>,<start_ip>,<end_ip>,<netmask>,<leasetime>

  1. Sample VM yaml to apply

apiVersion: kubevirt.io/v1 kind: VirtualMachine metadata: name: test-ovs-interface-1 spec: running: true template: metadata: labels: kubevirt.io/size: small kubevirt.io/domain: testvm spec: domain: devices: disks: - name: containerdisk disk: bus: virtio - name: cloudinitdisk disk: bus: virtio interfaces: - name: default masquerade: {} - bridge: {} name: ovs-br03 resources: requests: memory: 1024M hostname: myhostname1 networks: - name: default pod: {} - name: ovs-br03 multus: networkName: ovs-dnsmasq-test-woipam volumes: - name: containerdisk containerDisk: image: quay.io/kubevirt/fedora-cloud-container-disk-demo:latest - name: cloudinitdisk cloudInitNoCloud: userData: |- #cloud-config password: fedora chpasswd: { expire: False }

  1. Sample StatefulSet YAML to apply.

--- apiVersion: v1 kind: Service metadata: name: headless spec: ports: - port: 80 name: web selector: app: test clusterIP: None --- apiVersion: apps/v1 kind: StatefulSet metadata: name: test2 spec: replicas: 1 selector: matchLabels: app: test2 serviceName: headless template: metadata: labels: app: test2 annotations: k8s.v1.cni.cncf.io/networks: '[ { "name" : "ovs-dnsmasq-test-woipam"} ]' spec: securityContext: runAsUser: 1000 runAsGroup: 3000 containers: - name: test2 image: alpine ports: - containerPort: 80 name: web command: ["/bin/sh"] args: - -c - >- udhcpc -i net1 tail -f /dev/null securityContext: runAsUser: 0 #allowPrivilegeEscalation: false capabilities: add: ["NET_ADMIN"]

  1. An IPAllocation is made for every lease stored in the server. It is used to restore leases back to the DHCPServer. Leases are only restored to the vlanID mentioned. Lease will expire at leaseExpiry. Sample of how an IPAllocation looks

apiVersion: dhcp.plumber.k8s.pf9.io/v1alpha1 kind: IPAllocation metadata: creationTimestamp: "2022-11-09T12:18:58Z" generation: 1 name: 192.168.15.90 namespace: default resourceVersion: "189858" uid: 70ee31e1-d3b4-47f0-be92-0eb03cd33d57 spec: entityRef: test-ovs-interface-1 leaseExpiry: "1667998138" macAddr: 1e:8d:f0:c4:6c:8e vlanId: vlan3

  1. To test out the DHCPServer with KubeVirt Live Migration, connect the hosts with tunnels and set the MAC Address of the bridge.

ovs-vsctl set bridge ovs-br02 other_config:hwaddr=<interface mac address> # exit the daemon and bring the bridge up ip link set ovs-br02 up

Kubemacpool installation:

wget https://raw.githubusercontent.com/k8snetworkplumbingwg/kubemacpool/master/config/release/kubemacpool.yaml mac_oui=02:`openssl rand -hex 1`:`openssl rand -hex 1` sed -i "s/02:00:00:00:00:00/$mac_oui:00:00:00/" kubemacpool.yaml sed -i "s/02:FF:FF:FF:FF:FF/$mac_oui:FF:FF:FF/" kubemacpool.yaml kubectl apply -f ./kubemacpool.yaml kubectl label namespace default mutatevirtualmachines.kubemacpool.io=allocate


  Last updated by Anagha Pamidi on Jan 27, 2026
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