Frequently Asked Questions

docs/faq.md

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+# Frequently Asked Questions
+
+The present document lists a couple of frequently asked questions from our users and adopters.
+
+## How do I use x CNI with cluster?
+
+There is a great chance your tenant cluster CNI will conflict with infrastructure's cluster CNI.
+To avoid issues, you need first to make sure you are using VXLAN on your CNI, and a customized PORT. Below you can find a few examples:
+
+### Calico
+
+To use Calico CNI, you need to set `CALICO_IPV4POOL_IPIP` to `Never` and `CALICO_IPV4POOL_VXLAN` to `Always`. To customize your VXLAN port, you need to set `FELIX_VXLANPORT` to the customized port number.
+
+### Cilium
+
+To use Cilium CNI, make sure your `tunnel` is set to `vxlan`. To customize your VXLAN port, you need to set `tunnel-port` to the customized port number.
+
+### Flannel
+
+To use Flannel you will need to define your `Backend` manually in `net-conf.json` file, usually inside your `ConfigMap`. You must set `Type` to `vxlan` and `Port` to your customized port number, like the example below:
+```
+  net-conf.json: |
+    {
+      "Network": "10.243.0.0/16",
+      "Backend": {
+        "Type": "vxlan",
+        "Port": 1234
+      }
+    }
+```
+
+## Whenever I reboot a VM in Kubevirt, it looses is IP address, how do I fix it?
+
+Unfortunately anyone using cluster-api-provider-kubevirt to manage long-lived clusters that are not ephemeral will suffer from this. Basically there are 3 paths to workaround this issue for now:
+
+* Use a CNI that provides stable IP addresses, like for example `kube-ovn` or `ovn-k`.
+* Use a secondary network with Multus to attach this secondary network to the VirtualMachines. This will involve assigning static MAC addresses to the VirtualMachine through something like `kubemacpool` and map those MAC addresses to IP addresses on a DHCP server in that network.
+* Use ephemeral VirtualMachines by defining `spec.template.spec.virtualMachineTemplate.spec.runStrategy` to `Once` in your `KubevirtMachineTemplate`.
+
+
+## How do I use disk images that are not in a container registry?
+
+You can use [Containerized Data Importer
+](https://github.com/kubevirt/containerized-data-importer) as a solution to work with your disks on Kubevirt. The `DataVolume` definition would go inside `spec.template.spec.virtualMachineTemplate.spec.dataVolumeTemplates` inside your `KubevirtMachineTemplate`. An example to import an image from http would be:
+```
+  dataVolumeTemplates:
+  - apiVersion: cdi.kubevirt.io/v1beta1
+    kind: DataVolume
+    metadata:
+      annotations:
+        cdi.kubevirt.io/storage.deleteAfterCompletion: "false"
+      name: my-data-volume
+      namespace: default
+    spec:
+      pvc:
+        accessModes:
+        - ReadWriteOnce
+        resources:
+          requests:
+            storage: 40Gi
+        storageClassName: hostpath-csi
+      source:
+        http:
+          url: https://example.com/image.qcow2
+```
+
+After defining the `DataVolume` it needs to be added as a volume in your `KubevirtMachineTemplate` under `spec.template.spec.virtualMachineTemplate.spec.template.spec.volumes`. For the example provided this would look like:
+```
+    volumes:
+    - dataVolume:
+        name: my-data-volume
+        name: disk1
+```
+
+## Is it possible to use a VirtualMachineClusterInstancetype on my cluster?
+
+Yes, you can use either `VirtualMachineClusterInstancetype` or `VirtualMachineInstancetype`. To use it, you just need to set it under `spec.template.spec.virtualMachineTemplate.spec.instancetype` in your `KubevirtMachineTemplate`.
+Assuming you have a `VirtualMachineClusterInstancetype` named `standard`, this is how the setting would look like:
+```
+  instancetype:
+    kind: VirtualMachineClusterInstancetype
+    name: standard
+```
+