Is there any way to figure out which machines were created by which specific user? I've tried looking at the servers/details option, but even though it's possible to determine which machines were created by the same user (via the user_id) I'm unable to say "oh I know which username that user_id corresponds to!" I'd also rather not use the keypair field to group the machines.
As a small note, I'm using the http Compute API, not the nova command line client.
I managed to figure this out (at least for what I need). When a user does a POST to Openstack Identity for an authentication token, the returning json body contains information about the user (include the generated user_id). If you are able to capture the entire json body and parse through it, it can be used to filter the list of machines sent back from a GET request to Compute for server details. And then, you are able to figure out which machines are yours.