本文研究Nginx提供的缓存功能，下面是实操记录。

这篇博文基于前面文章的基础上搭建，至始至终都是root用户操作

http://www.jb51.cc/article/p-oaksciub-bro.html

缓存清除功能需要借助第三方模块ngx_cache_purge，其链接如下

https://github.com/FRiCKLE/ngx_cache_purge

下载其源码并安装进Nginx中去

cd /usr/local/src
git clone https://github.com/FRiCKLE/ngx_cache_purge.git

编译

cd Nginx-1.12.2
./configure --with-http_ssl_module \
--with-pcre=/usr/local/src/pcre-8.41 \
--with-zlib=/usr/local/src/zlib-1.2.11 \
--with-openssl=/usr/local/src/openssl-1.1.0g \
--with-http_stub_status_module \
--add-module=/usr/local/src/ngx_cache_purge

make

make install

配置
在Nginx.conf中添加如下配置块

proxy_cache_path  /usr/local/Nginx/cache1  levels=1:2 keys_zone=cache1:100m inactive=1d max_size=2g;

add_header X-Cache $upstream_cache_status;

location ^~ /static/ {
    proxy_cache  cache1;
    proxy_cache_key  $host$uri$is_args$args;
    proxy_cache_valid 200 304 301 302 10m;
    proxy_cache_methods GET; 
    proxy_cache_min_uses 3;
    proxy_cache_bypass $cookie_nocache $arg_nocache $arg_comment;

    proxy_pass  http://127.0.0.1:18080;

    expires 30d;
    access_log  logs/cache.log main; 
}

在相同的server块中，使用单独的location来配置缓存清除功能

location ~ /purge(/.*) {
    allow              127.0.0.1;
    deny               all;
    proxy_cache_purge  cache1 $host$1$is_args$args;
    access_log  logs/cache.log main;
}

完整的Nginx.conf配置如下：

user  root;
worker_processes  1;  

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"';

    access_log  logs/access.log  main;
    access_log  logs/access.log  main;

    sendfile        on;
    
    keepalive_timeout  65;

    proxy_cache_path  /usr/local/Nginx/cache1  levels=1:2 keys_zone=cache1:100m inactive=1d max_size=2g;

    server {
        listen       80;
        server_name  localhost;

        #access_log  logs/host.access.log  main;

        add_header X-Cache $upstream_cache_status;

        location ^~ /static/ {
            proxy_cache  cache1;
            proxy_cache_key  $host$uri$is_args$args;
            proxy_cache_valid 200 304 301 302 10m;
            proxy_cache_methods GET;
            proxy_cache_min_uses 3;
            proxy_cache_bypass $cookie_nocache $arg_nocache $arg_comment;

            proxy_cache_purge PURGE from 127.0.0.1;

            proxy_pass  http://127.0.0.1:18080;

            expires 30d;
            access_log  logs/cache.log main;-
        }

        location ~ /purge(/.*) {
            proxy_cache_purge  cache1 $host$1$is_args$args;
            allow              127.0.0.1;
            deny               all;
            access_log  logs/cache.log main;
        }

        location /ngx_status {
            stub_status;
            access_log off;
            allow 127.0.0.1;
            deny all;
        }

        location / {
            root   html;
            index  index.html index.htm;
        }

        #error_page  404              /404.html;

        # redirect server error pages to the static page /50x.html
        #
        error_page   500 502 503 504  /50x.html;
        location = /50x.html {
            root   html;
        }
    }


    server {
        listen       18080;
        server_name  localhost;

        location ^~ /static/ {
            root   html;
            expires  10d;
        }

        location / {
            root   html;
            index  index.html index.htm;
        }
        error_page   500 502 503 504  /50x.html;
        location = /50x.html {
            root   html;
        }
    }
}

检测并使配置生效

/usr/local/Nginx/sbin/Nginx -t
/usr/local/Nginx/sbin/Nginx -s reload

下面是/usr/local/Nginx下面的目录结构截图

ps auxf | grep Nginx | grep -v grep

注意此时发现已经多了一个cache manager进程。

测试

要求现在的Nginx cache功能不能和原来添加的模块功能相冲突。下面逐一进行测试。
curl -vo /dev/null 'http://127.0.0.1/'


curl -v http://127.0.0.1/ngx_status


curl -vo /dev/null 'http://127.0.0.1/static/a.gif'

根据配置，累计请求同一请求3次之后，才会缓存主

curl -vo /dev/null 'http://127.0.0.1/purge/static/a.gif'

再次请求该资源，发现缓存状态是MISS

curl -vo /dev/null 'http://127.0.0.1/static/a.gif'

测试中发现的问题

选项proxy_cache_min_uses表示同一个请求超过多少次才放入缓存，但是我发现，使用ngx_cache_purge模块删除之后，再次发送同一个请求，发现两次就缓存了。个人感觉这是个模块兼容性的bug。

参考文献 [1].http://Nginx.org/en/docs/http/ngx_http_proxy_module.html#proxy_cache [2].https://github.com/FRiCKLE/ngx_cache_purge [3].http://phl.iteye.com/blog/2256356 [4].http://blog.csdn.net/czp11210/article/details/28596649 [5].http://www.jackieathome.net/archives/411.html [6].http://blog.csdn.net/dengjiexian123/article/details/53386586