nginx.conf

load_module modules/ngx_http_image_filter_module.so;

# Inspiration: https://github.com/sergejmueller/sergejmueller.github.io/wiki/Nginx:-Real-time-image-resizing-and-caching
daemon off;
error_log /dev/stdout info;

http {

  proxy_cache_path /var/cache/nginx/images levels=1:2 keys_zone=resized:10m max_size=256m inactive=1h use_temp_path=off;
  access_log /dev/stdout;

  server {
    ## LISTEN
    listen 80 default_server;
    listen [::]:80 default_server;

    ## SERVER
    server_name resizer;

    ## CACHING
    location / {

      proxy_cache resized;
      proxy_cache_min_uses 2;
      proxy_cache_lock on;
      proxy_cache_valid 200 1d;
      proxy_cache_valid any 1m;
      proxy_cache_use_stale error timeout updating http_500 http_502 http_503 http_504;

      proxy_set_body none;
      proxy_redirect off;

      proxy_pass http://127.0.0.1:9001;
      proxy_pass_request_headers off;

      add_header X-Proxy-Cache $upstream_cache_status;
    }
  }

  server {
    listen 9001;
    root /var/www/html;

    location ~ \.(jpg|png|gif)$ {
      set $w "-";
      set $h "-";
      set $q "80";
      set $s "100";

      if ( $arg_w ) {
          set $w $arg_w;
      }
      if ( $arg_h ) {
          set $h $arg_h;
      }
      if ( $arg_q ) {
          set $q $arg_q;
      }
      if ( $arg_s ) {
          set $s $arg_s;
      }

      image_filter                resize $w $h;
      image_filter_jpeg_quality   $q;
      image_filter_buffer         10M;
      image_filter_interlace      on;
      image_filter_sharpen        $s;
    }
  }
}
events {
  worker_connections 1024;
}