[nova][oslo.log] global_request_id help
While doing something unrelated, I noticed this code  that shouldn't
need to exist if global_request_id is working. I threw out some debug
patches  to dump headers. Results:  (nova),  (placement). We're
tracking global_request_id ``req-a51f...``.
Nova is sending the global_request_id properly in the
X-Openstack-Request-Id header, and Placement is receiving it correctly,
because it's showing up in the expected spot in the Placement log line
(after the opening bracket, per the logging_context_format_string in
Placement is sending back the request_id (``req-b3ce...``) in the
x-openstack-request-id header in the response. (I thought this was a
bug, but it turns out this is correct per the design .)
So the problem is that the Nova log is printing ``None`` for the
global_request_id. Based on logging_context_format_string in
nova-cpu.conf , I expect it in the first field after the opening
bracket, just like for Placement.
If the global_request_id were showing up in the Nova log, we wouldn't
need to correlate the Nova and Placement sides of this conversation via
the Placement request_id, and we could get rid of  and its usages.
I don't understand how LOG.xxx() is supposed to glean this value. Can
someone help me find the disconnect?