How to setup VM hostname for VM runtime virtual machine

[AndrewR]

Hello.
I'm running couple of GVMs in Anthos cluster using VM runtime. For one of these GVMs I need to set hostname that is different from GVM name.
I tried to set it internally using hostnamectl, but every time I reboot the VM, hostname changes to GVM name

test-vm:~ # hostnamectl
Static hostname: static-vm
Transient hostname: test-vm

I can see that kubevirt.io/VirtualMachineInstance spec supports hostname

hostname <string>
Specifies the hostname of the vmi If not specified, the hostname will be set
to the name of the vmi, if dhcp or cloud-init is configured properly.

but vm.cluster.gke.io/VirtualMachine spec doesn't.

Since gvm is kind of a wrapper on kubevirt vm, is it possible to pass the hostname somehow?

[nmagcalengjr]

Hi @AndrewR,

Welcome to Google Cloud Community!

If you're wondering if you can pass a custom hostname to a VM runtime in Anthos, there are ways to manage VM networking and hostname configuration. However, this depends on the VM runtime you're using and how the VM is connected to the Anthos cluster.

You may refer to the following instructions below, a sample on how to create a VM by directly applying a VirtualMachine YAML manifest file with the kubectl CLI.

• Create a manifest that defines a VirtualMachine, such as my-vm.yaml, in the editor of your choice:

nano my-vm.yaml

• Copy and paste the following YAML definition:

apiVersion: vm.cluster.gke.io/v1
kind: VirtualMachine
metadata:
  name: VM_NAME
spec:
  osType: linux
  compute:
    cpu:
      vcpus: VCPU_NUMBER
    memory:
      capacity: MEMORY_SIZE
  interfaces:
    - name: eth0
      networkName: NETWORK_NAME
      default: true
  disks:
    - boot: true
      virtualMachineDiskName: DISK_NAME

• Save and close the manifest in your editor.

• Create the VM and disk using kubectl:

kubectl apply -f my-vm.yaml

• It can take a few minutes to create the VM. Check the status of the VM with the kubectl command:

kubectl get gvm VM_NAME

The following example output shows the VM in a Running state:

NAME    STATUS    AGE   IP
MY_VM   Running   64s   192.168.2.124

You can also refer to these documentations, which might help for future reference.

• Google Kubernetes Engine (GKE)
• Google Distributed Cloud (software only) for VMware overview
• Configure VM startup routines
• Connect to VMs that use VM Runtime on GDC
• Create a VM with a custom machine type
• Deploy an existing VM in a Google Distributed Cloud cluster using VM Runtime on GDC

I hope the above information is helpful.

[AndrewR]

> this depends on the VM runtime you're using
Are there different VM runtimes? I am using the one provided by Google.

> how the VM is connected to the Anthos cluster
again, is it possible to connect it multiple ways?

In your example of simple VM, if you create it like this
```name: VM_NAME```

The VM name and the VM hostname will be same VM_NAME. I need them to be different. Kubevirt allows it, but VM Runtime doesn't.