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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

Important: The core SLIRP binding was deprecated and removed in v1.3.0. This documentation covers the network binding plugin implementation of SLIRP.

The binding plugin replaces the core slirp binding API.

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.
  • Register the binding plugin on the Kubevirt CR.
  • Reference the network binding by name from the VM spec interface.

Note: The registered name for this binding should be slirp to maintain compatibility with existing VM specifications that reference the slirp binding.

Feature Gate

As of v1.5.0, the Network Binding Plugin feature is enabled by default and has no feature gate.

The slirp plugin similarly has no feature gate of its own, but the plugin needs to be made available in the cluster by registering it.

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:
  runStrategy: Always
  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