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Slirp

Overview

SLIRP provides user-space network connectivity.

Note: in slirp mode, the only supported protocols are TCP and UDP. ICMP is not supported.

Slirp network binding plugin

[v1.1.0]

The binding plugin replaces the core slirp binding API.

Note: The network binding plugin infrastructure is in Alpha stage. Please use them with care.

The slirp binding plugin consists of the following components:

  • Sidecar image.

As described in the definition & flow section, the slirp plugin needs to:

  • Assure access to the sidecar image.
  • Enable the network binding plugin framework FG.
  • Register the binding plugin on the Kubevirt CR.
  • Reference the network binding by name from the VM spec interface.

Note: In order for the core slirp binding to use the network binding plugin the registered name for this binding should be slirp.

Feature Gate

If not already set, add the NetworkBindingPlugins FG. 

kubectl patch kubevirts -n kubevirt kubevirt --type=json -p='[{"op": "add", "path": "/spec/configuration/developerConfiguration/featureGates/-",   "value": "NetworkBindingPlugins"}]'

Note: The specific slirp plugin has no FG by its own. It is up to the cluster admin to decide if the plugin is to be available in the cluster.

Slirp Registration

As described in the registration section, slirp binding plugin configuration needs to be added to the kubevirt CR.

To register the slirp binding, patch the kubevirt CR as follows: 

kubectl patch kubevirts -n kubevirt kubevirt --type=json -p='[{"op": "add", "path": "/spec/configuration/network",   "value": {
            "binding": {
                "slirp": {
                    "sidecarImage": "quay.io/kubevirt/network-slirp-binding:v1.1.0"
                }
            }
        }}]'

VM Slirp Network Interface

Set the VM network interface binding name to reference the one defined in the kubevirt CR.

---
apiVersion: kubevirt.io/v1
kind: VirtualMachine
metadata:
  labels:
    kubevirt.io/vm: vm-net-binding-slirp
  name: vm-net-binding-passt
spec:
  running: true
  template:
    metadata:
      labels:
        kubevirt.io/vm: vm-net-binding-slirp
    spec:
      domain:
        devices:
          disks:
          - disk:
              bus: virtio
            name: containerdisk
          - disk:
              bus: virtio
            name: cloudinitdisk
          interfaces:
          - name: slirpnet
            binding:
              name: slirp
          rng: {}
        resources:
          requests:
            memory: 1024M
      networks:
      - name: slirpnet
        pod: {}
      terminationGracePeriodSeconds: 0
      volumes:
      - containerDisk:
          image: quay.io/kubevirt/fedora-with-test-tooling-container-disk:v1.1.0
        name: containerdisk
      - cloudInitNoCloud:
          networkData: |
            version: 2
            ethernets:
              eth0:
                dhcp4: true
        name: cloudinitdisk