Removing Stale Virtual Machines and Virtual Machine Interfaces
This topic gives examples for removing stale VMs (virtual machines) and VMIs (virtual machine interfaces). Before you can remove a stale VM or VMI, you must first remove any back references associated to the VM or VMI.
Problem Example
The troubleshooting examples in this topic are based on the following problem example. A net-delete of the virtual machine 2a8120ec-bd18-49f4-aca0-acfc6e8fe74f returned the following messages that there are two VMIs that still have back-references to the stale VM.
The two VMIs must be deleted first, then the Neutron net-delete <vm_ID> command will complete without errors.
From neutron.log:
2014-03-10 14:18:05.208
DEBUG [urllib3.connectionpool]
"DELETE/virtual-network/2a8120ec-bd18-49f4-aca0-acfc6e8fe74f HTTP/1.1" 409 203
2014-03-10 14:18:05.278
ERROR [neutron.api.v2.resource] delete failed
Traceback (most recent call last):
File "/usr/lib/python2.7/dist-packages/neutron/api/v2/resource.py", line
84, in resource
result = method(request=request, **args)
File "/usr/lib/python2.7/dist-packages/neutron/api/v2/base.py", line
432, in delete
obj_deleter(request.context, id, **kwargs)
File
"/usr/lib/python2.7/dist-packages/neutron/plugins/juniper/contrail/contrail
plugin.py", line 294, in delete_network
raise e
RefsExistError: Back-References from
http: //127.0.0.1:8082/virtual-machine-interface/51daf6f4-7366-4463-a819-bd1
17fe3a8c8,
http: //127.0.0.1:8082/virtual-machine-interface/30882e66-e175-4fbb-862e-354
bb700b579 still exist Show Virtual Machines
Use the following command to show all of the virtual machines known to the Contrail API server. Replace the variable <config-node-IP> shown in the example with the IP address of the config-node in your setup.
http://<config-node-IP>:8082/virtual-machines
Example
In the following example, 03443891-99cc-4784-89bb-9d1e045f8aa6 is a stale VM that needs to be removed.
virtual-machines:
[
{
href:"http: //example-node:8082/virtual-machine/03443891-99cc-4784-89bb-9d1e045f8aa6",
fq_name:
[
"03443891-99cc-4784-89bb-9d1e045f8aa6"
],
uuid:"03443891-99cc-4784-89bb-9d1e045f8aa6"
},When the user attempts to delete the stale VM, a message displays that children to the VM still exist:
root@example-node:~# curl -X DELETE -H "Content-Type: application/json; charset=UTF-8" http: //127.0.0.1:8082/virtual-machine/03443891-99cc-4784-89bb-9d1e045f8aa6 Children http: //127.0.0.1:8082/virtual-machine-interface/0c32a82a-7bd3-46c7-b262-6d85b9911a0d still exist root@example-node:~#
The user opens http: //example-node:8082/virtual-machine/ 03443891-99cc-4784-89bb-9d1e045f8aa6, and sees a virtual-machine-interface (VMI) attached to it. The VMI must be removed before the VM can be removed.
However, when the user attempts to delete the VMI from the stale VM, they get a message that there is still a back-reference:
root@example-node:~# curl -X DELETE -H "Content-Type: application/json; charset=UTF-8" http: //<example-IP>:8082/virtual-machine-interface/0c32a82a-7bd3-46c7-b262-6d85b9911a0d Back-References from http: //<example-IP>:8082/instance-ip/6ffa29a1-023f-462b-b205-353da8e3a2a4 still exist root@example-node:~#
Because there is a back-reference from an instance-ip object still present, the instance-ip object must first be deleted, as follows:
root@example-node:~# curl -X DELETE -H "Content-Type: application/json; charset=UTF-8" http: //<example-IP>:8082/instance-ip/6ffa29a1-023f-462b-b205-353da8e3a2a4 root@example-node:~#
When the instance-ip is deleted, then the VMI and the VM can be deleted.
 | Note: To prevent inconsistency, be certain that the VM is not present in the Nova database before deleting the VM. |
Show Virtual Machines Using Python API
The following example shows how to view virtual machines using a Python API. This example shows virtual machines and back-references. Once you identify back-references and existing children, you can delete them first, then delete the stale VM.
root@example-node:~# source /opt/contrail/api-venv/bin/activate
File "<stdin>", line 1, in <module>
File "/opt/contrail/api-venv/lib/python2.7/site-packages/vnc_api/gen/vnc_api_client_gen.py", line 3793, in virtual_machine_interface_delete
content = self._request_server(rest.OP_DELETE, uri)
File "/opt/contrail/api-venv/lib/python2.7/site-packages/vnc_api/vnc_api.py", line 342, in _request_server
raise RefsExistError(content)
cfgm_common.exceptions.RefsExistError: Back-References from http: // <example-IP>:8082/instance-ip/6ffa29a1-023f-462b-b205-353da8e3a2a4 still exist
>>> (api-venv)root@example-node:~# python
Python 2.7.5 (default, Mar 10 2014, 03:55:35)
[GCC 4.6.3] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> from vnc_api.vnc_api import VncApi
>>> vh=VncApi()
>>> vh.virtual_machine_interface_delete(id='0c32a82a-7bd3-46c7-b262-6d85b9911a0d')
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/opt/contrail/api-venv/lib/python2.7/site-packages/vnc_api/gen/vnc_api_client_gen.py", line 3793, in virtual_machine_interface_delete
content = self._request_server(rest.OP_DELETE, uri)
File "/opt/contrail/api-venv/lib/python2.7/site-packages/vnc_api/vnc_api.py", line 342, in _request_server
raise RefsExistError(content)
cfgm_common.exceptions.RefsExistError: Back-References from http: // <example-IP>:8082/instance-ip/6ffa29a1-023f-462b-b205-353da8e3a2a4 still exist
>>> Delete Methods
Use help (vh) to show all delete methods supported.
Typical commands for deleting VMs and VMIs include:
- virtual_machine_delete() to delete a virtual machine
- instance_ip_delete() to delete an instance-ip.
