NGINX proxy_pass not caching content

Solution 1:

Turns out that thumbnail requests returned from Dropbox include the header

Cache-Control: no-cache

and Nginx will adhere to these headers unless they are explicitly ignored which can be done by simply using the following config line that will ignore any caching control.

proxy_ignore_headers    X-Accel-Expires Expires Cache-Control;

We also had issues placing the "proxy_ignore_headers" option in different areas within the nginx.conf file. Finally after much playing around we got it to work by explicitly setting it in the "location" block. The full snippet of the config file can be found below

    ## Proxy Server Caching
proxy_cache_path  /data/nginx/cache  levels=1:2 keys_zone=STATIC:50m inactive=2h max_size=2g;

## Proxy Server Setting
server {
    listen *:8181;

    location ~ ^/(.*) {
    set $dropbox_api 'api-content.dropbox.com';
    set $url    '$1';

    resolver 8.8.8.8;

    proxy_set_header    Host    $dropbox_api;
    proxy_hide_header   x-dropbox-thumbcachehit;
    proxy_hide_header   x-dropbox-metadata;
    proxy_hide_header   x-server-response-time;
    proxy_hide_header   x-dropbox-request-id;

    proxy_hide_header cache-control;
    proxy_hide_header expires;

    add_header cache-control "private";
    add_header x-cache $upstream_cache_status; # HIT / MISS / BYPASS / EXPIRED

    proxy_cache     STATIC;
    proxy_cache_valid       200  1d;
    proxy_cache_use_stale   error timeout invalid_header updating
                http_500 http_502 http_503 http_504;
    proxy_ignore_headers    X-Accel-Expires Expires Cache-Control;

    proxy_pass https://$dropbox_api/$url$is_args$args;
    }
}

Solution 2:

In order to cache the proxy response the request between Nginx and origin should be cookie-less:

  proxy_hide_header      Set-Cookie;
  proxy_ignore_headers   Set-Cookie;

See full configuration with invalidation methods: https://gist.github.com/mikhailov/9639593