How to configure Ubuntu Pro guest attachment¶

If Ubuntu Pro is enabled on a LXD host, guest instances can be automatically attached to the Pro subscription on that host.

Requirements¶

Ubuntu Pro must be enabled on the LXD host server.
The Pro client must be updated to the latest version.

Configure guest attachment¶

On the LXD host, run:

sudo pro config set lxd_guest_attach=<on|off|available>

The allowed values are:

on: New LXD guest instances are automatically attached to the host’s Pro subscription.
off: Default if unset. LXD guest instances cannot be attached to the host’s Pro subscription.
available: New LXD guest instances on the host are not attached automatically, but can be attached using the pro auto-attach command in the guest.

Automatic attachment¶

If lxd_guest_attach=on is set, instances automatically attach to its host’s Pro subscription at startup. The initial attach process can take some time. To confirm the subscription, run:

lxc exec <guest-instance> -- pro status

If the attach process has not completed, you will see the following lines within the output:

NOTICES
Operation in progress: pro.daemon.attempt_auto_attach

Force attachment¶

Guest instances that were started prior to setting lxd_guest_attach=on on the host will not automatically attach to the host’s Pro subscription. Neither will any instances on a host set to lxd_guest_attach=available.

To force such instances to attach, run:

lxc exec <guest-instance> -- pro auto-attach

Instance-level override¶

The lxd_guest_attach setting on the host can be overridden at the instance level, through the ubuntu_pro.guest_attach configuration option. The ubuntu_pro.guest_attach configuration key has three options: on, off, and available.

For example, if lxd_guest_attach is set to on on the host and you want to prevent Pro attachment in a new guest instance you are launching, run:

lxc launch ubuntu:24.04 <guest-instance> -c ubuntu_pro.guest_attach=off

To set this key on an instance that has already been created, see: Configure instance options.

All options for Pro guest attachment are described below.

	`on (host)`	`available (host)`	`off (host)`	`unset (host)`
`on (guest)`	auto-attach on start	auto-attach on start	guest attachment disabled	guest attachment disabled
`available (guest)`	attach on `pro auto-attach`	attach on `pro-auto-attach`	guest attachment disabled	guest attachment disabled
`off (guest)`	guest attachment disabled	guest attachment disabled	guest attachment disabled	guest attachment disabled
`unset (guest)`	auto-attach on start	attach on `pro-auto-attach`	guest attachment disabled	guest attachment disabled