Within OpenStack, each virtual machine instance running on a Compute nodes also a virtual machine running on a libvirt node.

If you ssh to a Compute node and run the command below you can get the names of each VM running or registered on this Compute node.

# virsh list –all
Id Name State
—————————————————-
2 instance-000000f0 running
– instance-00000024 shut off
– instance-00000039 shut off
– instance-000000ea shut off

So there is only one VM currently running on this Compute node, but which VM is it?

Well, we can figure that out pretty easily. See below.

# virsh dumpxml instance-000000f0 | grep uuid | grep name

<entry name=’uuid’>3103d38c-447d-40af-9607-56b26473ee72</entry>

Now we just have to map this UUID back to an OpenStack instance name

Here we have a nasty little awk grep to get the UUID and name of each OpenStack instance running in our cluster.

# nova list | grep -v “+” | grep -v ID | awk ‘{print $2 $3 $4}’

a402716b-73d0-4303-9331-202bc2386ab8|storage-perf-a
bd73f092-88c9-4af1-b569-c1176290841c|storage-perf-b
0ab8decb-6623-4e68-b8e4-b9cd522f6ea9|storage-perf-c
493c8afe-836e-4846-bdd0-029bb6e7f70e|storage-perf-d

Note that you can also get the instance name using a UUID,  see below

#nova show db79f6a2-455e-4f17-88d0-b3018d279c7c | grep instanceOS-EXT-SRV-ATTR:instance_name | instance-0000002a

OS-EXT-SRV-ATTR:instance_name | instance-0000002a

Update:

Thanks to TB for showing me this one. You can accomplish all of this via nova cli using the FQDN of the host.

(overcloud) [stack@undercloud ~]$ nova list --all --host comp39.localdomain --fields=name,host,instance_name,status
+--------------------------------------+----------------------+-------------------------------+-------------------+--------+
| ID | Name | Host | Instance Name | Status |
+--------------------------------------+----------------------+-------------------------------+-------------------+--------+
| 30fccd83-e517-4e56-a1df-5d5d454818ff | vm-name1 | comp39.localdomain | instance-0023a423 | ACTIVE |
| bc6bb4da-1cac-4603-ad52-2078f13cf6fd | vm-name-2 | comp39.localdomain | instance-0023a348 | ACTIVE |
+--------------------------------------+----------------------+-------------------------------+-------------------+--------+