Chapter 1. Introduction

Virtual machines can use host-based subscriptions instead of consuming entitlements from physical subscriptions. A host-based subscription is attached to a hypervisor and entitles it to provide subscriptions to its virtual machines. Many host-based subscriptions provide entitlements for unlimited virtual machines.

To allow virtual machines to inherit subscriptions from their hypervisors, you must install and configure virt-who. Virt-who queries the virtualization platform and reports hypervisor and virtual machine information to Red Hat Subscription Management.

When a virtual machine is registered with auto-attach enabled, and sufficient host-based subscriptions are available, one of the following behaviors occurs:

If auto-attach is enabled, but virt-who is not running or there are no host-based subscriptions available, Subscription Management attaches physical subscriptions to the virtual machines instead, which might consume more entitlements than intended.

If auto-attach is not enabled, virtual machines cannot use host-based subscriptions.

To see if a subscription requires virt-who, log in to to the Customer Portal at https://access.redhat.com, navigate to Subscriptions > Subscription Utilization, and select a subscription. If "Virt-Who: Required" appears in the SKU Details, you must configure virt-who in order to use that subscription.

A virtual machine requests a subscription from Subscription Management.

Subscription Management grants the virtual machine a temporary subscription, valid for a maximum of seven days, while it determines which hypervisor the virtual machine belongs to.

Virt-who connects to the hypervisor or virtualization manager and requests information about its virtual machines.

The hypervisor or virtualization manager returns a list of its virtual machines to virt-who, including each UUID.

Virt-who reports the list of virtual machines and their hypervisors to Subscription Management.

Subscription Management attaches a permanent subscription to the virtual machine, if sufficient entitlements are available.

To allow virtual machines to inherit subscriptions from their hypervisors, complete the following steps:

Virt-who is configured using files that specify details such as the virtualization type and the hypervisor or virtualization manager to query. The supported configuration is different for each virtualization platform.

[hypervisor1]
type=hyperv
server=hypervisor1.example.com
username=virt_who_user
encrypted_password=bd257f93d@482B76e6390cc54aec1a4d
hypervisor_id=hostname
owner=1234567

The type and server values depend on the virtualization platform. The following table provides more detail.

The username refers to a read-only user on Microsoft Hyper-V or VMware vCenter, which you must create before configuring virt-who. Virt-who uses this account to retrieve the list of virtual machines. You do not need a dedicated virt-who user for Red Hat hypervisors.

The general configuration file (located at '/etc/virt-who.conf') is created automatically when you install virt-who. You can use the default values or edit this file if required. It has three special sections: '[global]', '[defaults]', and '[system_environment]'.

The settings in the global section affect the overall operation of the application.

[global]
interval=3600 1
debug=True 2

The settings in the defaults that can be are applied as defaults to the configurations found in ''/etc/virt-who.d/.conf'. If you enable the options in this section, you don’t need to set them in ''/etc/virt-who.d/.conf' again.

[defaults]
owner=1234567 1
hypervisor_id=hostname 2

The settings in the system_environment are written to the system’s environment and are available for the duration of the process execution, it will be used whether virt-who was started as a service or from the command line.

[system_environment]
http_proxy= https://proxy.example.com:443 1
no_proxy=* 2