Create a service to connect with SSH - Managing VMs | Virtualization

About services
Enabling load balancer service creation by using the web console
Create a service with the web console
Create a service with virtctl
Creating a service by using the CLI
Connecting to a VM exposed by a service by using SSH

You can create a service for a virtual machine (VM) and connect to the IP address and port exposed by the service. Services provide excellent performance and are recommended for applications that are accessed from outside the cluster or within the cluster. Ingress traffic is protected by firewalls.

After you create a service with virtctl, you must add special: key to the spec.template.metadata.labels stanza of the VirtualMachine manifest. If the cluster network cannot handle the traffic load, consider using a secondary network for VM access.

About services

A Kubernetes service exposes network access for clients to an application running on a set of pods. Services offer abstraction, load balancing, and, in the case of the NodePort and LoadBalancer types, exposure to the outside world.

ClusterIP: Exposes the service on an internal IP address and as a DNS name to other applications within the cluster. A single service can map to multiple virtual machines. When a client tries to connect to the service, the client’s request is load balanced among available backends. ClusterIP is the default service type.
NodePort: Exposes the service on the same port of each selected node in the cluster. NodePort makes a port accessible from outside the cluster, provided that the node itself is externally accessible to the client.
LoadBalancer: Creates an external load balancer in the current cloud (if supported) and assigns a fixed, external IP address to the service.

For on-premise clusters, you can configure a load balancing service by deploying the MetalLB Operator.

Enabling load balancer service creation by using the web console

You can enable the creation of load balancer services for a virtual machine (VM) by using the OKD web console.

Prerequisites

You have configured a load balancer for the cluster.
You have logged in as a user with the cluster-admin role.
You created a network attachment definition for the network.

Procedure

Go to Virtualization → Overview.
On the Settings tab, click Cluster.
Expand General settings and SSH configuration.
Set SSH over LoadBalancer service to on.

Create a service with the web console

You can create a node port or load balancer service for a virtual machine (VM) by using the OKD web console.

Prerequisites

You configured the cluster network to support either a load balancer or a node port.
To create a load balancer service, you enabled the creation of load balancer services.

Procedure

Navigate to VirtualMachines and select a virtual machine to view the VirtualMachine details page.
On the Details tab, select SSH over LoadBalancer from the SSH service type list.
Optional: Click the copy icon to copy the SSH command to your clipboard.

Verification

Check the Services pane on the Details tab to view the new service.

Create a service with virtctl

You can create a service for a virtual machine (VM) by using the virtctl command-line tool.

Prerequisites

You installed the virtctl command-line tool.
You configured the cluster network to support the service.
The environment where you installed virtctl has the cluster permissions required to access the VM. For example, you ran oc login or you set the KUBECONFIG environment variable.

Procedure

Create a service by running the following command:
```
$ virtctl expose vm <vm_name> --name <service_name> --type <service_type> --port <port>
```
where:
<vm_name>

Specifies the name of the VM you are exposing.

<service_name>

Specifies a user-defined name for the service you are creating.

<service_type>

Specifies one of ClusterIP, NodePort, or LoadBalancer.

<port>
Specifies the network port on the VM that the service will expose.

Example:
$ virtctl expose vm example-vm --name example-service --type NodePort --port 22

Verification

Verify the service by running the following command:
```
$ oc get service
```

Creating a service by using the CLI

You can create a service and associate it with a virtual machine (VM) by using the command line.

Prerequisites

You configured the cluster network to support the service.
You have installed the OpenShift CLI (oc).

Procedure

Edit the VirtualMachine manifest to add the label for service creation. Add special: key to the spec.template.metadata.labels stanza:
```
apiVersion: kubevirt.io/v1
kind: VirtualMachine
metadata:
  name: example-vm
  namespace: example-namespace
spec:
  runStrategy: Halted
  template:
    metadata:
      labels:
        special: key
# ...
```
Labels on a virtual machine pass through to the pod. The special: key label must match the label in the spec.selector attribute of the Service manifest.
Save the VirtualMachine manifest file to apply your changes.
Create a Service manifest to expose the VM:
```
apiVersion: v1
kind: Service
metadata:
  name: example-service
  namespace: example-namespace
spec:
# ...
  selector:
    special: key
  type: NodePort
  ports:
    protocol: TCP
    port: 80
    targetPort: 9376
    nodePort: 30000
```
- spec.selector defines the label that you added to the spec.template.metadata.labels stanza of the VirtualMachine manifest.
- spec.type defines the type of service by the way it is exposed. Choose one of ClusterIP, NodePort, or LoadBalancer.
- spec.ports defines a collection of network ports and protocols to expose from the virtual machine.
Save the Service manifest file.
Create the service by running the following command:
```
$ oc create -f example-service.yaml
```
Restart the VM to apply the changes.

Verification

Query the Service object to verify that it is available:
```
$ oc get service -n example-namespace
```

Connecting to a VM exposed by a service by using SSH

You can connect to a virtual machine (VM) that a service exposes by using SSH.

Prerequisites

You created a service to expose the VM.
You have an SSH client installed.
You are logged in to the cluster.

Procedure

Run the following command to access the VM:
```
$ ssh <user_name>@<ip_address> -p <port>
```
where:

<ip_address>

Specifies the cluster IP for a cluster IP service, the node IP for a node port service, or the external IP address for a load balancer service.