Connecting a virtual machine to a service mesh

OpenShift Virtualization is now integrated with OpenShift Service Mesh. You can monitor, visualize, and control traffic between pods that run virtual machine workloads on the default pod network with IPv4.

Adding a virtual machine to a service mesh

To add a virtual machine (VM) workload to a service mesh, enable automatic sidecar injection in the VM configuration file by setting the sidecar.istio.io/inject annotation to true. Then expose your VM as a service to view your application in the mesh.

Important

To avoid port conflicts, do not use ports used by the Istio sidecar proxy. These include ports 15000, 15001, 15006, 15008, 15020, 15021, and 15090.

Prerequisites

You have installed the OpenShift CLI (oc).
You have installed the Service Mesh Operator.

Procedure

Edit the VM configuration file to add the sidecar.istio.io/inject: "true" annotation.

Example configuration file:

apiVersion: kubevirt.io/v1
kind: VirtualMachine
metadata:
  labels:
    kubevirt.io/vm: vm-istio
  name: vm-istio
spec:
  runStrategy: Always
  template:
    metadata:
      labels:
        kubevirt.io/vm: vm-istio
        app: vm-istio
      annotations:
        sidecar.istio.io/inject: "true"
    spec:
      domain:
        devices:
          interfaces:
          - name: default
            masquerade: {}
          disks:
          - disk:
              bus: virtio
            name: containerdisk
          - disk:
              bus: virtio
            name: cloudinitdisk
        resources:
          requests:
            memory: 1024M
      networks:
      - name: default
        pod: {}
      terminationGracePeriodSeconds: 180
      volumes:
      - containerDisk:
          image: registry:5000/kubevirt/fedora-cloud-container-disk-demo:devel
        name: containerdisk

spec.template.metadata.labels.app specifies the key/value pair (label) that must be matched to the service selector attribute.
spec.template.metadata.annotations.sidecar.istio.io/inject is the annotation to enable automatic sidecar injection.
spec.template.spec.domain.devices.interfaces.masquerade is the binding method (masquerade mode) for use with the default pod network.

Run the following command to apply the VM configuration:
```
$ oc apply -f <vm_name>.yaml
```
where:

<vm_name>

Specifies the name of the virtual machine YAML file.
Create a Service object to expose your VM to the service mesh:
```
apiVersion: v1
kind: Service
metadata:
  name: vm-istio
spec:
  selector:
    app: vm-istio
  ports:
    - port: 8080
      name: http
      protocol: TCP
```
- spec.selector.app specifies the service selector that determines the set of pods targeted by a service. This attribute corresponds to the spec.metadata.labels field in the VM configuration file. In the above example, the Service object named vm-istio targets TCP port 8080 on any pod with the label app=vm-istio.
Run the following command to create the service:
```
$ oc create -f <service_name>.yaml
```
where:

<service_name>

Specifies the name of the service YAML file.

Additional resources

Installing the Service Mesh Operator