nginx hook before upload - nginx

Question

I've created an intranet http site where users can upload their files, I have created a location like this one:
location /upload/ {
limit_except POST { deny all; }
client_body_temp_path /home/nginx/tmp;
client_body_in_file_only on;
client_body_buffer_size 1M;
client_max_body_size 10G;
proxy_set_header X-upload /upload/;
proxy_set_header X-File-Name $request_body_file;
proxy_set_body $request_body_file;
proxy_redirect off;
proxy_pass_request_headers on;
proxy_pass http://localhost:8080/;
}
Quite easy as suggested in the official doc. When upload is complete the proxy_pass directive calls the custom URI and makes filesystem operations on newly created temp file.
curl --request POST --data-binary "#myfile.img" http://myhost/upload/
Here's my problem: I need to have some kind of custom hook/operation telling me when the upload begins, something nginx can call before starting the http stream, is there a way to achieve that ? I mean, before uploading big files I need to call a custom url (something like proxy_pass) to inform the server about this upload and execute certain operations.
Is there a way to achieve it ? I have tried with echo-nginx module but it didn't succeed with these http POST (binary form-urlencoded). I don't want to use external scripts to deal with the upload and keep these kind of operations inside nginx (more performant)
Thanks in advance.
Ben

Answer 1

Self replying.
I have found this directive in order to solve my own request.
auth_request <something>
So I can do something like:
location /upload/ {
...
# Pre auth
auth_request /somethingElse/;
...
}
# Newly added section
location /somethingElse/ {
...
proxy_pass ...;
}
This seems to be fine and working, useful for uploads as well as for general auth or basic prechecks