$ssl_protocol in nodejs POST requests after 1.9.4

[Reinis Rozitis]

Hello.
I have a strange issue where for a POST request having any form data Nginx
after version 1.9.4 doesn't log $ssl_protocol (or any other $ssl_*)
variable.


I have a configured custom accesslog:

log_format main '... $ssl_protocol $ssl_cipher $server_port';

A simple script ( for example from
https://nodejs.dev/learn/make-an-http-post-request-using-nodejs ) will
generate following accesslog entry with all the variables being empty:

[08/May/2021:19:11:50 +0300] ...  "axios/0.21.1" - - 443


The moment you remove the form data everything is being logged:

[08/May/2021:19:10:58 +0300] ...  HTTP/1.1" 200 772 "-" "axios/0.21.1"
TLSv1.2 ECDHE-RSA-AES128-GCM-SHA256 443


I tried to debug the requests and see the difference (besides
Content-Length) but I wasn't able to pinpoint the issue. 
I tried various nodejs libraries ('request' etc) and also native approach -
all produce same results - empty POST requests are fine, the moment you post
any form data the $ssl_* become empty.
I can't reproduce it with curl - tried varios requests with and without
data, with chunked encoding etc - everything is being logged as expected.


One could say that the problem is on the Node side - but what has changed
between 1.9.4 and 1.9.5 that breaks the logging? 

Maybe someone has any suggestions or ideas how to investigate this further?

Wbr