hyperv-guest-agent

hyperv-guest-agent extension

This system extension provides the Hyper-V Linux guest integration daemons from the kernel's tools/hv tree, run as Talos extension services:

Service	Binary	Purpose
ext-hyperv-kvp	hv_kvp_daemon	Key-Value Pair exchange — reports guest IPv4/IPv6, hostname, and OS details to the host so Get-VMNetworkAdapter is populated
ext-hyperv-vss	hv_vss_daemon	VSS — freezes/thaws the data partition so Hyper-V can take application-consistent checkpoints

Talos already ships the kernel side (hv_vmbus, hv_utils); this extension adds the missing user-space daemons. The daemons are statically linked against the base toolchain and require no shared libraries at runtime.

Prerequisites

The daemons attach to /dev/vmbus/hv_kvp and /dev/vmbus/hv_vss, which are created by the hv_utils kernel module. Make sure the corresponding integration services are enabled on the VM (on the Hyper-V host):

Enable-VMIntegrationService -VMName '<vm-name>' -Name 'Key-Value Pair Exchange'
Enable-VMIntegrationService -VMName '<vm-name>' -Name 'VSS'

If hv_utils is not auto-loaded on your Talos version, add it via machine config:

machine:
  kernel:
    modules:
      - name: hv_utils

Installation

See Installing Extensions.

Testing

Confirm the extension services are running:

$ talosctl -n <node> service ext-hyperv-kvp
NODE     <node>
ID       ext-hyperv-kvp
STATE    Running
HEALTH   ?
EVENTS   [Running]: Started task ext-hyperv-kvp ...

$ talosctl -n <node> logs ext-hyperv-kvp

On the Hyper-V host, the guest IP should now be reported:

Get-VMNetworkAdapter -VMName '<vm-name>' | Select-Object -ExpandProperty IPAddresses

Notes & limitations

• DNS/DHCP reporting is best-effort. hv_kvp_daemon shells out to the distro helper scripts hv_get_dns_info / hv_get_dhcp_info to report DNS servers and DHCP status to the host. Those scripts are not shipped, so those two fields stay empty; IP address, hostname, and OS reporting are unaffected (they come from the kernel/sysfs, not the helpers).
• Host → guest IP injection is not supported. The KVP feature that lets the host push a static IP into the guest relies on the same (unshipped) helper scripts and a writeable network-config path; Talos networking is managed by machine config instead.
• VSS freezes the /var (ephemeral) partition. The read-only squashfs root needs no freeze. Validate checkpoint consistency against your workload before relying on it.