disable request body buffering for file upload

[garyc]

Hello, Thanks for the hint I have managed to use the auth request module to
check available disk space before accepting the request so I only attempt
the upload if there is disk space available. 

I am now having another problem. Our debian environment uses a rootfs
ramdisk which has just under 1GB of memory, when i accept the upload request
I can see the rootfs disk fill steadily until it is full at which point the
upload POST request is returned with error 500 and the message 'System error
- unable to complete file upload'. 

Are there any configuration settings that would instruct nginx to use
another disk when accepting the client request body? 

I have experimented with client_body_in_file_only and client_body_temp_path
and can observe that temporary files are created if they are small enough
for the rootfs to handle, files that are rejected when the rootfs fill ups
have no temporary file created so presumably this happens after the initial
read to the rootfs.

Many thanks
Gary

Posted at Nginx Forum: https://forum.nginx.org/read.php?2,275567,276155#msg-276155