下面的Nginx.conf实现nginx在前端做反向代理服务器的完整配置文件的例子，处理js、png等静态文件，jsp/php等动态请求转发到其它服务器tomcat/apache
user  www www;
worker_processes  auto;
worker_cpu_affinity auto;
error_log  logs/error.log;
worker_rlimit_nofile 102400;
pid        logs/nginx.pid;
events {
    use epoll;
    worker_connections  102400;
}
http {
    include       mime.types;
    default_type  application/octet-stream;
    log_format  main  '$remote_addr - $remote_user [$time_local] "$request" '
                      '$status $body_bytes_sent "$http_referer" '
                      '"$http_user_agent" "$http_x_forwarded_for"'
                      '"$upstream_cache_status"';
    access_log  logs/access.log  main;
    server_tokens off;
    sendfile        on;
    tcp_nopush     on;
    keepalive_timeout  65;
    #Compression Settings
    gzip on;
    gzip_comp_level 6;
    gzip_http_version 1.1;
    gzip_proxied any;
    gzip_min_length 1k;
    gzip_buffers 16 8k;
    gzip_types text/plain text/css text/javascript application/json application/javascript application/x-javascript application/xml;
    gzip_vary on;
    #end gzip
    # http_proxy Settings
    client_max_body_size   10m;
    client_body_buffer_size   128k;
    proxy_connect_timeout   75;
    proxy_send_timeout   75;
    proxy_read_timeout   75;
    proxy_buffer_size   4k;
    proxy_buffers   4 32k;
    proxy_busy_buffers_size   64k;
    proxy_temp_file_write_size  64k;
    proxy_buffering on;
    proxy_temp_path /usr/local/nginx1.10/proxy_temp;
    proxy_cache_path /usr/local/nginx1.10/proxy_cache levels=1:2 keys_zone=my-cache:100m max_size=1000m inactive=600m max_size=2g;
    #load balance Settings
    upstream backend {
        hash $remote_addr consistent;
        server 192.168.31.141:80 weight=1 max_fails=2 fail_timeout=10s;
        server 192.168.31.250:80 weight=1 max_fails=2 fail_timeout=10s;
    }
    #virtual host Settings
    server {
        listen       80;
        server_name  localhost;
        charset utf-8;
        location  ~/purge(/.*) {
           allow 127.0.0.1;
           allow 192.168.31.0/24;
           deny all;
           proxy_cache_purge my-cache $host$1$is_args$args;
        }
        location / {
            index  index.php index.html index.htm;
            proxy_pass        http://backend;
            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;
            proxy_ignore_headers Set-Cookie;
            proxy_hide_header Set-Cookie;
            proxy_next_upstream error timeout invalid_header http_500 http_502 http_503 http_504;
        }
        location ~ .*\.(gif|jpg|png|html|htm|css|js|ico|swf|pdf)(.*) {
           proxy_pass  http://backend;
           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;
           proxy_next_upstream error timeout invalid_header http_500 http_502 http_503 http_504;
           proxy_cache my-cache;
           add_header Nginx-Cache $upstream_cache_status;
           proxy_cache_valid 200 304 301 302 8h;
           proxy_cache_valid 404 1m;
           proxy_cache_valid any 1d;
           proxy_cache_key $host$uri$is_args$args;
           expires 30d;
           access_log off;
        }
        location /nginx_status {
            stub_status on;
            access_log off;
            allow 192.168.31.0/24;
            deny all;
        }
    }
}

$upstream_cache_status这个变量来显示缓存的状态，我们可以在配置中添加一个http头来显示这一状态，
$upstream_cache_status包含以下几种状态： 
·MISS 未命中，请求被传送到后端 
·HIT 缓存命中 
·EXPIRED 缓存已经过期请求被传送到后端 
·UPDATING 正在更新缓存，将使用旧的应答 
·STALE 后端将得到过期的应答
expires ： 在响应头里设置Expires:或Cache-Control:max-age，返回给客户端的浏览器缓存失效时间。