Nginx reverse proxy, cache and cache clearing example analysis

#user nobody;
worker_processes 1;

#error_log logs/error.log;
#error_log logs/error.log notice;
#error_log logs/error.log info;

#pid    logs/nginx.pid;


events {
  worker_connections 1024;
}


http {
  log_format main '$remote_addr - $remote_user [$time_local] "$request" '
           '$status $body_bytes_sent "$http_referer" '
           '"$http_user_agent" "$http_x_forwarded_for"'
       '$upstream_addr $upstream_status $request_time $upstream_response_time';


  access_log /var/log/nginx/access.log main;
  error_log  /var/log/nginx/error.log;

  server_tokens off;
  include    mime.types;
  default_type application/octet-stream;
  sendfile    on;
  tcp_nopush   on;
  client_max_body_size 10m;
  client_body_buffer_size 128k;

  proxy_connect_timeout 300;
  proxy_send_timeout 300;
  proxy_read_timeout 300;
  proxy_buffer_size 64k;
  proxy_buffers 4 512k;
  proxy_busy_buffers_size 512k;
  proxy_temp_file_write_size 512k;
  proxy_temp_path  /data/nginx/proxy_temp;
  proxy_cache_path /data/nginx/proxy_cache levels=1:2 keys_zone=cache_one:2000m inactive=3d max_size=500g;

  proxy_redirect off;
  proxy_set_header host $host;
  proxy_set_header x-real-ip $remote_addr;
  proxy_set_header x-forwarded-for $proxy_add_x_forwarded_for;

  gzip on;
  gzip_min_length 1k;
  gzip_buffers 4 16k;
  gzip_http_version 1.1;
  gzip_comp_level 2;
  gzip_types text/plain application/x-javascript text/css application/xml;
  gzip_vary on;

  upstream go {
    server www.cnblogs.com:80 weight=4;
    #server 42.121.252.58:80 weight=4;
  }

  server {

      listen  192.168.55.133:80;
      #server_name www.cnblogs.com;
      access_log /var/log/nginx/go.access.log main;
      error_log  /var/log/nginx/go.error.log error;


      location / {
          proxy_cache cache_one;
          #proxy_cache_valid 200 304 301 302 2h;
          #proxy_cache_valid any 2h;
          #expires 1d;
          add_header x-cache $upstream_cache_status;
          proxy_pass http://go;
          proxy_cache_key  $uri$is_args$args;
      }

      location ~ /purge(/.*) {
        allow       127.0.0.1;
        allow       192.168.55.0/24;
        deny        all;
        proxy_cache_purge cache_one $1$is_args$args;
    }

  }
}