Deleted flavors break VM resize and Horizon UI

[okozachenko1203]

Context

A VM created using one flavor, then that flavor deleted somehow. Now this non-existing flavor produces 2 issues

• Horizon admin UI outputs the same number of error messages (like Error: Unable to retrieve instance size information. [Details] Flavor xxx could not be found. (HTTP 404)) as the instance number in the VM table
• VM resize doesn't work for those VMs created by using this deleted flavor

  root@ostack-controller-01:~# openstack server stop 16a2f715-f7ce-45f9-ac8d-f3072791f624
root@ostack-controller-01:~# openstack server resize --flavor 3846abe4-7d9f-4506-92a4-e0ccfce573dc 16a2f715-f7ce-45f9-ac8d-f3072791f624
root@ostack-controller-01:~# openstack server resize confirm 16a2f715-f7ce-45f9-ac8d-f3072791f624
Cannot 'confirmResize' instance 16a2f715-f7ce-45f9-ac8d-f3072791f624 while it is in vm_state stopped (HTTP 409) (Request-ID: req-598fc277-6b9f-403b-9607-b104867c1155)
root@ostack-controller-01:~# openstack server start 16a2f715-f7ce-45f9-ac8d-f3072791f624
root@ostack-controller-01:~# openstack server resize confirm 16a2f715-f7ce-45f9-ac8d-f3072791f624
Cannot 'confirmResize' instance 16a2f715-f7ce-45f9-ac8d-f3072791f624 while it is in vm_state active (HTTP 409) (Request-ID: req-ebf19636-1dfb-4f02-90a9-11cc879ea4af)

How to reproduce

1. Create a VM using an existing flavor
2. Delete that flavor
3. Try resize or visit Horizon UI admin panel to get the VM list

Solutions

• Disallow the flavor deletion if there is a VM using that flavor at least (changes required in nova)
• Or allow the flavor deletion regardless of its usage as is. And add exception handling in horizon and nova side.(But need to check first if old flavor is required in the resize process for some reason) (changes required in horizon and nova)

[mnaser]

@okozachenko1203 i believe that the flavor is embedded in the database, so it should be able to get whatever info it needs.

also, when the resize is failing, can you get some logs from nova-compute?

[okozachenko1203]

I can reproduce this in my devstack. When i access admin>compute>instances dashboard

Oct 24 08:53:37 mcapi devstack@n-api.service[126478]: [pid: 126478|app: 0|req: 1782/7124] 38.108.68.23 () {60 vars in 1214 bytes} [Tue Oct 24 08:53:37 2023] GET /compute/v2.1/flavors/3 => generated 74 bytes in 14 msecs (HTTP/1.1 404) 9 headers in 378 bytes (1 switches on core 0)
Oct 24 08:53:37 mcapi devstack@n-api.service[126477]: DEBUG nova.api.openstack.wsgi [None req-ebdbae27-ecd3-4378-bfb8-a0026794c0ef demo admin] Calling method '<bound method FlavorsController.show of <nova.api.openstack.compute.flavors.FlavorsController object at 0x7f55b9692680>>' {{(pid=126477) _process_stack /opt/stack/nova/nova/api/openstack/wsgi.py:513}}
Oct 24 08:53:37 mcapi devstack@n-api.service[126477]: INFO nova.api.openstack.wsgi [None req-ebdbae27-ecd3-4378-bfb8-a0026794c0ef demo admin] HTTP exception thrown: Flavor 3 could not be found.
Oct 24 08:53:37 mcapi devstack@n-api.service[126477]: DEBUG nova.api.openstack.wsgi [None req-ebdbae27-ecd3-4378-bfb8-a0026794c0ef demo admin] Returning 404 to user: Flavor 3 could not be found. {{(pid=126477) __call__ /opt/stack/nova/nova/api/openstack/wsgi.py:936}}

[okozachenko1203]

but i was able to resize the instance which was created using the flavor deleted

[mnaser]

Reference https://bugs.launchpad.net/horizon/+bug/2042362

[mnaser]

I've pushed up a fix here..

https://review.opendev.org/c/openstack/horizon/+/899752

@ricolin @okozachenko1203 can we help track this down and perhaps cherry-pick into our horizon image?

[mnaser]

this is already fixed