前端web缓存有多重方式实现，原理就是队请求结果页面静态化并设置一个超时期限，缓存页面过期后，新请求到达时重新到后端web服务器获取内容更 新；没有nginx前比较流行的方法是squid，但squid不能充分利用处理器的多核特性，越来越多的网站选用nginx来做前端的web缓存。
要想使用nginx的缓存功能要保证nginx添加了proxy模块。我们可以使用-V选项(大写的V，小写的v是看版本号的)来查看nginx的编译参数。我使用的是默认的参数编译的，如下所示：
root@SNDA-172-17-12-117:/usr/local/nginx# ./nginx -V
nginx version: nginx/1.2.3
built by gcc 4.4.3 (Ubuntu 4.4.3-4ubuntu5.1)
TLS SNI support enabled
configure arguments: --sbin-path=/usr/local/nginx/nginx
--conf-path=/usr/local/nginx/nginx.conf
--pid-path=/usr/local/nginx/nginx.pid --with-http_ssl_module
--with-pcre=/usr/local/src/pcre-8.21
--with-zlib=/usr/local/src/zlib-1.2.7
nginx的所有模块必须在编译的时候添加，不能再运行的时候动态加载，默认的编译选项下包含的模块，如果你不是显示的用参数关闭它。
nginx默认安装的模块如下
| 模块名称 | 描述 | 版本 | 如何禁用 |
|---|---|---|---|
| Core | Control ports, locations, error pages, aliases, and other essentials. |
|
--without-http |
| Access | Allow/deny based on IP address. |
|
--without-http_access_module |
| Auth Basic | Basic HTTP authentication. |
|
--without-http_auth_basic_module |
| Auto Index | Generates automatic directory listings. |
|
--without-http_autoindex_module |
| Browser | Interpret "User-Agent" string. | 0.4.3 | --without-http_browser_module |
| Charset | Recode web pages. |
|
--without-http_charset_module |
| Empty GIF | Serve a 1x1 image from memory. | 0.3.10 | --without-http_empty_gif_module |
| FastCGI | FastCGI Support. |
|
--without-http_fastcgi_module |
| Geo | Set config variables using key/value pairs of IP addresses. | 0.1.17 | --without-http_geo_module |
| Gzip | Gzip responses. |
|
--without-http_gzip_module |
| Headers | Set arbitrary HTTP response headers. |
|
|
| Index | Controls which files are to be used as index. |
|
|
| Limit Requests | Limit frequency of connections from a client. | 0.7.20 | --without-http_limit_req_module |
| Limit Zone | Limit simultaneous connections from a client. Deprecated in 1.1.8, use Limit Conn Instead. | 0.5.6 | --without-http_limit_zone_module |
| Limit Conn | Limit concurrent connections based on a variable. |
|
--without-http_limit_conn_module |
| Log | Customize access logs. |
|
|
| Map | Set config variables using arbitrary key/value pairs. | 0.3.16 | --without-http_map_module |
| Memcached | Memcached support. |
|
--without-http_memcached_module |
| Proxy | Proxy to upstream servers. |
|
--without-http_proxy_module |
| Referer | Filter requests based on Referer header. |
|
--without-http_referer_module |
| Rewrite | Request rewriting using regular expressions. |
|
--without-http_rewrite_module |
| SCGI | SCGI protocol support. | 0.8.42 | --without-http_scgi_module |
| Split Clients | Splits clients based on some conditions | 0.8.37 | --without-http_split_clients_module |
| SSI | Server-side includes. |
|
--without-http_ssi_module |
| Upstream | For load-balancing. |
|
--without-http_upstream_ip_hash_module (ip_hash directive only) |
| User ID | Issue identifying cookies. |
|
--without-http_userid_module |
| uWSGI | uWSGI protocol support. | 0.8.40 | --without-http_uwsgi_module |
| X-Accel | X-Sendfile-like module. |
|
proxy模块中常用的指令时proxy_pass和proxy_cache.
nginx的web缓存功能的主要是由proxy_cache、fastcgi_cache指令集和相关指令集完成，proxy_cache指令负 责反向代理缓存后端服务器的静态内容，fastcgi_cache主要用来处理FastCGI动态进程缓存(这里我不是很清楚这两个指令的区别，好像功能 上都差不多，尤其后面这句话的意思，是我翻译过来的)。
确认proxy模块安装好后，下面对nginx的配置文件进行设置，重点部分如标红字体所示。
这是我的nginx.conf配置文件。
user www-data;
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 {
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" "$host"';
#access_log logs/access.log main;
sendfile on;
#tcp_nopush on;
#keepalive_timeout 0;
keepalive_timeout 65;
#Compression Settings
gzip on;
gzip_http_version 1.0;
gzip_comp_level 2;
gzip_proxied any;
gzip_min_length 1100;
gzip_buffers 16 8k;
gzip_types text/plain text/css application/x-javascript text/xml application/xml application/xml+rss text/javascript;
# Some version of IE 6 don't handle compression well on some mime-types,
# so just disable for them
gzip_disable "MSIE [1-6].(?!.*SV1)";
# Set a vary header so downstream proxies don't send cached gzipped
# content to IE6
gzip_vary on;
#end gzip
#cache begin
proxy_buffering on;
proxy_cache_valid any 10m;
proxy_cache_path /data/cache levels=1:2 keys_zone=my-cache:8m max_size=1000m inactive=600m;
proxy_temp_path /data/temp;
proxy_buffer_size 4k;
proxy_buffers 100 8k;
#cache end
## Basic reverse proxy server ##
## Apache (vm02) backend for www.example.com ##
upstream apachephp {
server www.quancha.cn:8080; #Apache1
}
## Start www.quancha.cn ##
server {
listen 80;
server_name *.quancha.cn;
access_log logs/quancha.access.log main;
error_log logs/quancha.error.log;
root html;
index index.html index.htm index.php;
## send request back to apache1 ##
location / {
proxy_pass http://apachephp;
proxy_cache my-cache;
proxy_cache_valid 200;
#Proxy Settings
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_max_temp_file_size 0;
proxy_connect_timeout 90;
proxy_send_timeout 90;
proxy_read_timeout 90;
proxy_buffer_size 4k;
proxy_buffers 4 32k;
proxy_busy_buffers_size 64k;
proxy_temp_file_write_size 64k;
##End Proxy Settings
}
}
## End www.quancha.cn ##
}
配置文件中以proxy_开头的指令我们大都可以字面意思得到理解。请务必注意一点proxy_cache_path和proxy_temp_path设置的目录需要在同一分区，因为它们之间是硬链接的关系。
最后执行重新加载nginx配置文件启动nginx ：/usr/local/nginx/sbin/nginx -s reload，来迎接着激动人心的时刻吧。
