Occasionally, the proxy error logs show a message like:
an upstream response is buffered to a temporary fileIt’s not clear why responses are sometimes buffered to disk or how this behavior is controlled.
Response buffering in Kong and how it's controlled
Uses:
Kong Gateway
TL;DR
What is response buffering in Kong and how is it controlled?
Kong buffers upstream responses to a temporary file when a client can’t consume the response data as fast as the upstream application produces it, freeing the upstream to serve other requests sooner. Set proxy_max_temp_file_size to 0 (injected via the kong.conf file) to disable this buffering, though this is rarely recommended.
Problem
Cause
A client usually has a much slower connection and can not consume the response data as fast as it is produced by an upstream application. Kong tries to buffer the whole response to release the upstream application as soon as possible.
This ensures the upstream application is free to serve other requests and a slow client can still consume the response. Disk buffering does not always happen for every response, if the client can consume the whole response in a timely manner no buffering occurs.
Solution
It is possible to set proxy_max_temp_file_size to 0 to remove response buffering, though there are not many scenarios where this would be desirable so use with caution.
To set this it is required to inject the value into the Nginx config at run time, this can be configured by injecting Nginx directives using the kong.conf file.
nginx_proxy_proxy_max_temp_file_size=0