Kubevirt V0.7.0

Introduction

Kubevirt v0.7.0 was released a few weeks ago and brings a bunch of new features that this blog post will detail.

the full list is visible here but we will pick the ones oriented to the end user

Features

hugepages support

To use hugepages as backing memory, we need to indicate a desired amount of memory (resources.requests.memory) and size of hugepages to use (memory.hugepages.pageSize)

apiVersion: kubevirt.io/v1alpha1
kind: VirtualMachine
metadata:
  name: myvm
spec:
  domain:
    resources:
      requests:
        memory: "64Mi"
    memory:
      hugepages:
        pageSize: "2Mi"
    disks:
    - name: myimage
      volumeName: myimage
      disk: {}
  volumes:
    - name: myimage
      persistentVolumeClaim:
        claimname: myclaim

Note that

  • a node must have pre-allocated hugepages
  • hugepages size cannot be bigger than requested memory
  • requested memory must be divisible by hugepages size

setting network interface model and MAC address

the following syntax within interfaces section allows us to set both a mac address and network model

kind: VM
spec:
  domain:
    devices:
      interfaces:
        - name: red
          macAddress: de:ad:00:00:be:af
          model: e1000
          bridge: {}
  networks:
  - name: red
    pod: {}

alternative network models can be

  • e1000
  • e1000e
  • ne2k_pci
  • pcnet
  • rtl8139
  • virtio

setting a disks serial number

The new keyword serial in the disks section allows us to specify a serial number

apiVersion: kubevirt.io/v1alpha1
kind: VirtualMachine
metadata:
  name: myvm
spec:
  domain:
    resources:
      requests:
        memory: "64Mi"
    disks:
    - name: myimage
      volumeName: myimage
      serial: sn-11223344
      disk: {}
  volumes:
    - name: myimage
      persistentVolumeClaim:
        claimname: myclaim

specifying the CPU model

Setting the CPU model is possible via spec.domain.cpu.model. The following VM will have a CPU with the Conroe model:

metadata:
  name: myvmi
spec:
  domain:
    cpu:
      # this sets the CPU model
      model: Conroe
...

The available models are listed here

Additionally, we can also use

  • host-model
  • host-passthrough

virtctl expose

To access services listening within vms, we can expose their ports using standard kubernetes services. Alternatively, we can make use of the virtctl binary to achieve the same result:

  • to expose a cluster ip service
virtctl expose virtualmachineinstance vmi-ephemeral --name vmiservice --port 27017 --target-port 22
  • to expose a node port service
virtctl expose virtualmachineinstance vmi-ephemeral --name nodeport --type NodePort --port 27017 --target-port 22 --node-port 30000
  • to expose a load balancer service
virtctl expose virtualmachineinstance vmi-ephemeral --name lbsvc --type LoadBalancer --port 27017 --target-port 3389

Kubernetes compatible networking approach (SLIRP)

In slirp mode, virtual machines are connected to the network backend using QEMU user networking mode. In this mode, QEMU allocates internal IP addresses to virtual machines and hides them behind NAT.

kind: VM
spec:
  domain:
    devices:
      interfaces:
        - name: red
          slirp: {} # connect using SLIRP mode
  networks:
  - name: red
    pod: {}

Role aggregation for our roles

Every KubeVirt installation after version v0.5.1 comes a set of default RBAC cluster roles that can be used to grant users access to VirtualMachineInstances.

The kubevirt.io:admin and kubevirt.io:edit ClusterRoles have console and VNC access permissions built into them.

Conclusion

This concludes our review of latest kubevirt features. Enjoy them !