Hello,

I'm trying to configure nginx to use proxy_cache_background_update but it seems like after expiry it still waits for the full roundtrip to the backend, returning a MISS in X-Cache-Status. What am I MISSing?

I'm using nginx 1.11.12 under ubuntu 14.04 running inside docker, but hopefully this is too much detail.

location ~ ^/?(\d+/[^/]+)?/?$
{
expires 20s;

proxy_cache app_cache;
proxy_cache_lock on;

proxy_cache_bypass $http_upgrade;

proxy_pass http://172.17.0.2:5000;
proxy_http_version 1.1;
error_log /nginxerror.log debug;

add_header X-Cache-Status $upstream_cache_status;

proxy_cache_use_stale error timeout updating http_500 http_502 http_503 http_504;
proxy_cache_background_update on;

break;
}

NB: This is a duplicate of my so question, I was kindly advised on the nginx IRC to repost here for better chances, the original question is here: http://stackoverflow.com/questions/43223993/nginx-proxy-cache-background-update-after-cache-expiry