Nginx filter module - dynamic resize image

nginx-image-filter.conf

server {
     # Internal image resizing server.
        server_name  localhost;
		listen       888 ;
		allow 127.0.0.1;
		deny all;
		
		access_log  /var/log/nginx/image_access.log;
		error_log  /var/log/nginx/image_error.log;
		
		set $image_dir /opt/nginx/html/image;
		root $image_dir;
		
		# eg 
		# link http://localhost:888/media/image/a/abc.png?width=300
		# dir /opt/nginx/html/image/a/abc.png
		location ~* \.(gif|jpg|png)$ { #ignore case sensitive
 			image_filter_buffer 50M;
			image_filter_jpeg_quality 95;
			image_filter_transparency on;
			#alias $image_dir;
			
			
			set $width 250;
			#set $height 500;
			
			if ( $arg_width ) {
				set $width $arg_width;
				#set $height $arg_height;
			}
			#image_filter resize $width $height;
			image_filter resize $width -;
			error_page   415 = /empty;
		} 
		
		location = /empty {
			empty_gif;
		}
		
		location / {
			deny  all;
		}
    }

	
# https://www.nginx.com/blog/nginx-caching-guide/
proxy_cache_path  /opt/nginx/cache/images/  levels=1:2    keys_zone=STATIC:10m	inactive=24h  max_size=1g;

server {
    # public cache server.
    # add md5 hash link for secure protection 
    server_name cdn.xxx.me;
	listen    80;

	access_log  /var/log/nginx/cdn_access.log;
	error_log  /var/log/nginx/cdn_error.log;
	
	location / {
        deny  all;
    }

    location /media/image/ {
	proxy_pass http://localhost:888/;
	proxy_set_header       Host $host;
	proxy_buffering        on;
	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;
		
    }
}