使用nginx的proxy_cache做网站缓存

发布时间：2014-09-05 15:27:52作者：知识屋

为什么要做web cache，我想大家最主要的是解决流量的压力。随着网站流量的提升，如果只是单台机器既处理静态文件，又处理动态脚本，显然效率很难上升，不能处理日益上涨的流量压力。与此同时某些网站的页面内容并不是经常变化，因此我们可以分两层架构来组织网站。前端web缓存+后端web服务器

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 ##