Description of problem::
Customer has an OSP 16.2 setup with 100+ pre-provisioned nodes, and needs to upgrade to OSP 17.1.

Step 7 of procedure in [1] in overcloud adoption and preparation instructs to run the following command:
~~~
$ openstack overcloud node provision --debug --stack <stack> \
--output /home/stack/overcloud_adopt/baremetal-deployment.yaml \
tripleo-<stack>-baremetal-deployment.yaml
~~~

This command fails in customer setup because the nodes are pre-provisioned instead of baremetal.

Right now, the suggested workaround is to manually create file baremetal-deployment.yaml, which is not pratical and error prone when dealing with large deployments.

We would like to request an automated way of creating this file when pre-provisioned nodes are involved.

Thank you!

[1] https://access.redhat.com/documentation/en-us/red_hat_openstack_platform/17.1/html-single/framework_for_upgrades_16.2_to_17.1/index#running-the-overcloud-upgrade-preparation_overcloud-adoption