Accessing a virtual machine by using the cluster FQDN

You can access a virtual machine (VM) that is attached to a secondary network interface from outside the cluster by using the fully qualified domain name (FQDN) of the cluster.

Configuring a DNS server for secondary networks

The Cluster Network Addons Operator (CNAO) deploys a Domain Name Server (DNS) server and monitoring components when you enable the deployKubeSecondaryDNS feature gate in the HyperConverged custom resource (CR).

Prerequisites

• You installed the OpenShift CLI (oc).

• You configured a load balancer for the cluster.

• You logged in to the cluster with cluster-admin permissions.

Procedure

1. Create a load balancer service to expose the DNS server outside the cluster by running the oc expose command according to the following example:

   $ oc expose -n kubevirt-hyperconverged deployment/secondary-dns --name=dns-lb \
     --type=LoadBalancer --port=53 --target-port=5353 --protocol='UDP'

2. Retrieve the external IP address by running the following command:

   $ oc get service -n kubevirt-hyperconverged

   Example output

   NAME       TYPE             CLUSTER-IP     EXTERNAL-IP      PORT(S)          AGE
   dns-lb     LoadBalancer     172.30.27.5    10.46.41.94      53:31829/TCP     5s

3. Edit the HyperConverged CR in your default editor by running the following command:

   $ oc edit hyperconverged kubevirt-hyperconverged -n kubevirt-hyperconverged

4. Enable the DNS server and monitoring components according to the following example:

   apiVersion: hco.kubevirt.io/v1beta1
   kind: HyperConverged
   metadata:
     name: kubevirt-hyperconverged
     namespace: kubevirt-hyperconverged
   spec:
       featureGates:
         deployKubeSecondaryDNS: true
       kubeSecondaryDNSNameServerIP: "10.46.41.94" (1)
   # ...

   1	Specify the external IP address exposed by the load balancer service.

5. Save the file and exit the editor.

6. Retrieve the cluster FQDN by running the following command:

    $ oc get dnses.config.openshift.io cluster -o jsonpath='{.spec.baseDomain}'

   Example output

   openshift.example.com

7. Point to the DNS server by using one of the following methods:

   • Add the kubeSecondaryDNSNameServerIP value to the resolv.conf file on your local machine.

     Editing the resolv.conf file overwrites existing DNS settings.

   • Add the kubeSecondaryDNSNameServerIP value and the cluster FQDN to the enterprise DNS server records. For example:

     vm.<FQDN>. IN NS ns.vm.<FQDN>.

     ns.vm.<FQDN>. IN A 10.46.41.94

Connecting to a VM on a secondary network by using the cluster FQDN

You can access a running virtual machine (VM) attached to a secondary network interface by using the fully qualified domain name (FQDN) of the cluster.

Prerequisites

• You installed the QEMU guest agent on the VM.

• The IP address of the VM is public.

• You configured the DNS server for secondary networks.

• You retrieved the fully qualified domain name (FQDN) of the cluster.

Procedure

1. Retrieve the network interface name from the VM configuration by running the following command:

   $ oc get vm -n <namespace> <vm_name> -o yaml

   Example output

   apiVersion: kubevirt.io/v1
   kind: VirtualMachine
   metadata:
     name: example-vm
     namespace: example-namespace
   spec:
     running: true
     template:
       spec:
         domain:
           devices:
             interfaces:
               - bridge: {}
                 name: example-nic
   # ...
         networks:
         - multus:
             networkName: bridge-conf
           name: example-nic (1)

   1	Note the name of the network interface.

2. Connect to the VM by using the ssh command:

   $ ssh <user_name>@<interface_name>.<vm_name>.<namespace>.vm.<cluster_fqdn>

Additional resources

• Configuring ingress cluster traffic using a load balancer

• Load balancing with MetalLB

• Configuring IP addresses for virtual machines