Elisamara Aoki Goncalves 1f91cd1ee0 Update documentation for Kubevirt

Add Usage Examples sections.
Create KubeVirt Architecture section.
Fix minor editorial issues.
Fix grammar and formatting issues.

Story: 2010931
Task: 50286

Change-Id: I6118d0af848d07f3764eeae5ea8467864c65fceb
Signed-off-by: Elisamara Aoki Goncalves <elisamaraaoki.goncalves@windriver.com>

2024-09-04 22:08:20 +00:00

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Live Migration Support for VMs

Live migration is a process during which a running moves to another compute node while the guest workload continues to run and remain accessible.

Enable the Live Migration Support

Live migration is enabled by default in recent versions of KubeVirt. Versions prior to v0.56 must be enabled in the feature gates. The feature gates field in the KubeVirt Custom Resource must be expanded by adding the live migration to it.

Limitation for live migrations:

using a must have a shared access mode to be live migrated.
Live migration is not allowed with a pod network binding of bridge interface type ().
Live migration requires ports 49152, 49153 to be available in the virt-launcher pod. If these ports are explicitly specified in a masquarade interface, live migration will not function.

Initiate Live Migration

Live migration is initiated by posting a object to the cluster. The example below starts a migration process for a virtual machine instance vmi-fedora.

cat <<EOF> migration.yaml
apiVersion: kubevirt.io/v1
kind: VirtualMachineInstanceMigration
metadata:
  name: migration-job
spec:
  vmiName: vmi-fedora
EOF

kubectl apply -f migration.yaml

Use virtctl to initiate Live Migration

Live migration can also be initiated using virtctl.

virtctl migrate vmi-fedora

Live Migration for SRIOV based VMs

It is possible to live migrate based , but there are some limitations:

Specify the MAC address statically and on host the name of the interface should be same on source and target host.
Specify the Static IP address.

Below is an example manifest for using a static MAC address:

apiVersion: kubevirt.io/v1
kind: VirtualMachine
metadata:
  labels:
    special: vmi-sriov-network
  name: vmi-sriov-test-vm
spec:
  running: true
  template:
    metadata:
      labels:
        kubevirt.io/size: small
        kubevirt.io/domain: fedora
    spec:
      domain:
        cpu:
          cores: 4
        devices:
          disks:
          - name: containerdisk
            disk:
              bus: virtio
          - name: cloudinitdisk
            disk:
              bus: virtio
          interfaces:
          - macAddress: "02:00:00:00:00:01"
            name: sriov-net1
            sriov: {}
          rng: {}
        resources:
          requests:
            memory: 1024M
      networks:
      - multus:
          networkName: sriov-net1
        name: sriov-net1
      volumes:
      - containerDisk:
          image: docker.io/kubevirt/fedora-cloud-container-disk-demo:devel
        name: containerdisk
      - cloudInitNoCloud:
          networkData: |
            ethernets:
              sriov-net1:
                addresses:
                - 10.10.10.12/24
                gateway: 10.10.10.1
                match:
                  macAddress: "02:00:00:00:00:01"
                nameservers:
                  addresses:
                  - 10.96.0.10
                  search:
                  - default.svc.cluster.local
                  - svc.cluster.local
                  - cluster.local
                set-name: sriov-link-enabled
            version: 2
          userData: |-
            #!/bin/bash
            echo "fedora" |passwd fedora --stdin
        name: cloudinitdisk

Below is an example manifest to initiate the live migration:

apiVersion: kubevirt.io/v1
kind: VirtualMachineInstanceMigration
metadata:
  name: migration-job-1
spec:
  vmiName: vmi-sriov-test-vm

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