##### truncated vhost config:

server {
  location /upload {
    upload_pass @handler;
    upload_pass_args on;
    upload_pass_form_field "(.*)";
    upload_set_form_field name $upload_file_name;
    upload_set_form_field type $upload_content_type;
    upload_set_form_field path $upload_tmp_path;
    upload_store /tmp;
  }

  location @handler {
    lua_code_cache off;
    content_by_lua_file /path/to/upload.lua;
  }
}


##### upload.lua:

local ngx_form = require "form_parser_module"
local params = {}
local mb_conv = 1024 * 1024
local post_defs = {}

post_defs["content_type"] = ngx.var.http_content_type
post_defs["content_length"] = ngx.var.http_content_length
post_defs["maxinput"] = 2 * mb_conv
post_defs["maxfilesize"] = 1 * mb_conv
post_defs["args"] = params

ngx.say("post defs:")
for k, v in pairs( post_defs ) do
  ngx.say(k, ": ", v)
end

ret, post_args, tmpfiles = ngx_form.get_post_args(post_defs)
if ret then
  ngx_form.removetmpfiles(tmpfiles)
  ngx.exit(500)
end

ngx.say("\npost args:")
for k, v in pairs( post_args ) do
  ngx.say(k, ": ", v)
end

ngx.say("\n* request body:")
ngx.say(ngx.req.get_body_data())


##### output:

$ curl -F file=@TDXBN.gif http://localhost/upload
* post defs:
content_type: multipart/form-data; boundary=----------------------------ff78acc43147
maxinput: 2097152
content_length: 358
maxfilesize: 1048576
args:

* post args:

* request body:
------------------------------ff78acc43147


##### output of echo_request_body in location @handler:

$ curl -F file=@TDXBN.gif http://localhost/upload
------------------------------a1c27b5f4c35
Content-Disposition: form-data; name="name"

TDXBN.gif
------------------------------a1c27b5f4c35
Content-Disposition: form-data; name="type"

image/gif
------------------------------a1c27b5f4c35
Content-Disposition: form-data; name="path"

/tmp/0009525769
------------------------------a1c27b5f4c35--


##### output of echo $request_body and echo $echo_request_body in location @handler:

$ curl -F file=@TDXBN.gif http://localhost/upload
------------------------------69811337d604
Content-Disposition: form-data; name="