<p>以前做网站的时候遇到了网站的访问量很大，而导致后端处理程序响应超时而导致的一些问题。当时采用的架构是nginx+php-fastcgi，同事想到了用nginx-proxycache来做页面缓存，效果也还行。下面我想介绍一下varnish的使用技巧</p>    <h2><strong>准备</strong></h2>    <p>varnish严格来说是可以当作一个代理服务器的软件，直接将 HTTP 请求转发到 php-cgi ,然后交给php处理,varnish会获取经过php处理后的数据,最后返回给浏览器。如图</p>    <p style="text-align:center"><img src="https://simg.open-open.com/show/444380fc92f288794f187323c69dd10d.jpg"></p>    <p>但是，现在 php-fastcgi 已经被逐渐淘汰了，也就是说我们一般情况下不会使用 php-fastcgi ，那么我们不能直接将varnish与php组合，因为php-fpm的交互方式为socket，而不再是监听本机的9000端口</p>    <p>所以我们必须找一个的媒介,连接 varnish 和 php-fpm , nginx 可以扮演这个媒介,如下图：</p>    <p style="text-align:center"><img src="https://simg.open-open.com/show/60071c1c861c29e6c1274502f785cf71.jpg"></p>    <p>那么问题来了，根据研究发现， varnish 处理 http 请求不如 nginx 那么高效。所以如果我们让 nginx 做前锋，这样就更完美了。那我们需要怎么才能达到这个目的呢，下面我们来整理一下流程</p>    <p style="text-align:center"><img src="https://simg.open-open.com/show/8d13afae02a727554b28811fd0b720bf.jpg"></p>    <p>下面就来实现一下图三的架构吧。</p>    <p>事先需要准备 nginx , varnish , php-fpm , php 这些软件，OS是 ubuntu ，所有软件都可以用 apt-get install 来安装，不了解包名全称的话可以先 apt-get update ，更新一下源，然后再用 apt-cache search xxx 来查找软件包名</p>    <p>安装完 varnish 后，可以使用 service varnish 回车，查看可操作选项 * Usage: /etc/init.d/varnish {start|stop|restart|reload|force-reload|configtest} ,一般安装完毕后，系统会自动启动 varnish 的, nginx 也是一样,便不赘述了</p>    <h2><strong>配置</strong></h2>    <p>安装完所需的软件后，下面需要配置这些软件，来实现这个架构</p>    <h3><strong>nginx部分</strong></h3>    <p>vi /etc/nginx/nginx.conf</p>    <pre>  <code class="language-groovy">http {      ## proxy global setting      proxy_connect_timeout 5;      proxy_read_timeout 60;      proxy_send_timeout 5;      proxy_buffer_size 16k;      proxy_buffers 4 64k;      proxy_busy_buffers_size 128k;      ##END      ## cache proxy pass      upstream cache {              server  127.0.0.1:6081;      }      ##END      ## php proxy pass      upstream php {               server  127.0.0.1:8080;      }      ##END      # Basic Settings      sendfile on;      tcp_nopush on;      tcp_nodelay on;      keepalive_timeout 65;      types_hash_max_size 2048;      server_tokens off;      #depend on nginx-extras 需要安装nginx-extras才能定义Server      more_set_headers 'Server: Bird-shark';      # server_names_hash_bucket_size 64;      # server_name_in_redirect off;      include /etc/nginx/mime.types;      default_type application/octet-stream;      ##      # SSL Settings      ##      ssl_protocols TLSv1 TLSv1.1 TLSv1.2; # Dropping SSLv3, ref: POODLE      ssl_prefer_server_ciphers on;      ##      # Logging Settings      ##      access_log /var/log/nginx/access.log;      error_log /var/log/nginx/error.log;      ##      # Gzip Settings      ##      gzip on;      gzip_disable "msie6";      gzip_vary on;      gzip_proxied any;      gzip_comp_level 6;      gzip_buffers 16 8k;      gzip_http_version 1.1;      gzip_types text/plain text/css application/json application/javascript text/xml application/xml application/xml+rss text/javascript;      ##      # Virtual Host Configs      ##      include /etc/nginx/conf.d/*.conf;      include /etc/nginx/sites-enabled/*;    }</code></pre>    <p>vi /etc/nginx/sites-available/default</p>    <pre>  <code class="language-groovy">server {      listen 80 default_server;      listen [::]:80 default_server;      index index.html index.htm index.php;      server_name localhost;      location ~ .*\.(gif|jpg|png|css|js|flv|ico|swf|html)$ {          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_pass http://cache;      }      # pass the PHP scripts to FastCGI server listening on 127.0.0.1:9000      #      location / {          proxy_pass http://php;          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_pass_header Server;      }  }  server {      listen 8080;      root /var/www/html;      index  index.html index.htm index.php;      location / {          if (!-e $request_filename){              rewrite  ^(.*)$  /index.php?s=$1  last;              break;          }          try_files $uri $uri/ =404;      }      location ~ ^(.+\.php)(.*)$ {          fastcgi_pass unix:/var/run/php5-fpm.sock;          fastcgi_intercept_errors on;          fastcgi_buffers 8 128k;          fastcgi_index  index.php;          fastcgi_param  SCRIPT_FILENAME $document_root$fastcgi_script_name;          include        fastcgi_params;      }  }</code></pre>    <h3><strong>varnish部分</strong></h3>    <p>vi /etc/varnish/default.vcl</p>    <pre>  <code class="language-groovy">vcl 4.0;    # Default backend definition. Set this to point to your content server.  backend default {      .host = "127.0.0.1";      .port = "8080";  }  acl purgers {      "localhost";      #"103.22.188.169";  }  sub vcl_recv {      # Happens before we check if we have this in cache already.      #      # Typically you clean up the request here, removing cookies you don't need,      # rewriting the request, etc.      if (req.restarts == 0) {          unset req.http.X-Purger;      }      if(req.method == "PURGE"){          if(!client.ip ~ purgers){              return(synth(405,"Not Allowed."));          }          return (purge);          #ban("obj.http.x-url ~ " + req.url);      }      if(req.method == "GET" && req.url ~ "\.(js|css|jpg|png|gif|swf|jpeg|ico)$"){          unset req.http.cookie;      }  }    sub vcl_backend_response {      #set beresp.http.x-url = bereq.url;      if (bereq.url ~ "\.(js|css|jpg|png|gif|swf|jpeg|ico)$") {          unset beresp.http.Cache-Control;          unset beresp.http.set-cookie;          set beresp.ttl = 10h;          set beresp.http.Cache-Control = "max-age=36000";          set beresp.do_gzip = true;      }      if(bereq.url ~ "\.html$"){          set beresp.ttl = 10m;          set beresp.do_gzip = true;          unset beresp.http.Cache-Control;          unset beresp.http.Pragma;          set beresp.http.Cache-Control = "max-age=600";          unset beresp.http.Expires;      }  }    sub vcl_deliver {      if (obj.hits > 0) {          set resp.http.X-Cache = "HIT from " + req.http.host;          #set resp.http.X-Cache-Hits = obj.hits;      } else {          set resp.http.X-Cache = "MISS from " + req.http.host;      }      if (req.http.X-Purger) {          set resp.http.X-Purger = req.http.X-Purger;      }      unset resp.http.X-Powered-By;      unset resp.http.Server;             unset resp.http.Via;      unset resp.http.X-Varnish;             unset resp.http.Age;      #unset resp.http.x-url; # Optional  }  sub vcl_hit {      if (req.method == "PURGE") {          return (synth(200,"Purged."));      }  }  sub vcl_miss {      if (req.method == "PURGE") {          return (synth(404,"Purged."));      }  }  sub vcl_purge {      if (req.method == "PURGE") {          #set req.http.X-Purge = "Purged";          ban("req.url ~ "+req.url);          #return (restart);          set req.method = "GET";          set req.http.X-Purger = "Purged";          return (restart);      }  }  sub vcl_hash {      hash_data(req.url);      if (req.http.host) {          hash_data(req.http.host);      } else {          hash_data(server.ip);      }      if (req.http.cookie) {          hash_data(req.http.cookie);      }      if (req.http.Accept-Encoding ~ "gzip") {          hash_data("gzip");      } elseif (req.http.Accept-Encoding ~ "deflate") {          hash_data("deflate");      }  }</code></pre>    <h2><strong>测试&分析</strong></h2>    <h3><strong>1. 在不使用缓存模块的情况下</strong></h3>    <p>vi /etc/nginx/sites-available/default</p>    <pre>  <code class="language-groovy">#location ~ .*\.(gif|jpg|png|css|js|flv|ico|swf|html)$ {  #    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_pass http://cache;  #}</code></pre>    <p>先用chrome浏览器访问查看请求头</p>    <p><img src="https://simg.open-open.com/show/4d8782a013b6b091325970266f828cb4.png"></p>    <p>我们再使用curl,在服务器上执行以下命令</p>    <pre>  <code class="language-groovy">curl -k -v 'http://192.168.99.1/Public/Home/images/t_navigation_logo.png' -H 'Pragma: no-cache' -H 'Accept-Encoding: gzip, deflate, sdch' -H 'Accept-Language: zh,en;q=0.8,zh-CN;q=0.6' -H 'Upgrade-Insecure-Requests: 1' -H 'User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/52.0.2743.116 Safari/537.36' -H 'Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8' -H 'Connection: keep-alive' --compressed</code></pre>    <p>发现有输出内容。</p>    <p>然后，反选disable cache</p>    <p><img src="https://simg.open-open.com/show/b72c9b38f0b016c9dd1d14faf1f73745.png"></p>    <p>然后在服务器上执行以下命令</p>    <pre>  <code class="language-groovy">curl  -k -v 'http://192.168.99.1/Public/Home/images/t_navigation_logo.png' -H 'If-None-Match: "57c6b733-1962"' -H 'Accept-Encoding: gzip, deflate, sdch' -H 'Accept-Language: zh,en;q=0.8,zh-CN;q=0.6' -H 'Upgrade-Insecure-Requests: 1' -H 'User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/52.0.2743.116 Safari/537.36' -H 'Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8' -H 'Connection: keep-alive' -H 'If-Modified-Since: Wed, 31 Aug 2016 10:53:39 GMT' --compressed</code></pre>    <p>发现只返回了头部信息，然而没有内容返回</p>    <p>然后我们比较两个命令 发现区别就在 -H 'Pragma: no-cache' 和 -H 'If-Modified-Since: Wed, 31 Aug 2016 10:53:39 GMT' -H 'If-None-Match: "57c6b733-1962"'</p>    <p>57c6b733-1962 这串字符对应的是服务器响应给浏览器的 ETag 部分的内容，然后我们修改一下部分的内容</p>    <pre>  <code class="language-groovy">curl  -k -v 'http://192.168.99.1/Public/Home/images/t_navigation_logo.png' -H 'If-None-Match: "57c6b733-1234"' -H 'Accept-Encoding: gzip, deflate, sdch' -H 'Accept-Language: zh,en;q=0.8,zh-CN;q=0.6' -H 'Upgrade-Insecure-Requests: 1' -H 'User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/52.0.2743.116 Safari/537.36' -H 'Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8' -H 'Connection: keep-alive' -H 'If-Modified-Since: Wed, 31 Aug 2016 10:53:39 GMT' --compressed</code></pre>    <p>在服务器端执行一下。发现有内容返回，所以这个 ETag 相当于 token ，它不是由 nginx 随便生成的，且跟请求链接应是一一对应的，用来标识缓存的,当服务器返回的状态为 304 的时候,这时候我们浏览器会直接找到本地的缓存数据</p>    <h3><strong>2. 在使用缓存模块的情况下</strong></h3>    <p>vi /etc/nginx/sites-available/default</p>    <pre>  <code class="language-groovy">location ~ .*\.(gif|jpg|png|css|js|flv|ico|swf|html)$ {      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_pass http://cache;  }</code></pre>    <p>用浏览器查看响应头</p>    <p>发现 X-Cache:MISS from 192.168.99.1 .这表示缓存未命中，然后我们刷新 X-Cache:HIT from 192.168.99.1 ，这时候发现已经命中了。</p>    <p>对于已经命中的资源文件，我们如果将其删除会出现什么效果呢，答案是，其依然可以访问，除非重启或者将缓存清除</p>    <p>但是对PURGE显然是不对外公开的,以下是服务器端用curl清除varnish缓存的命令</p>    <pre>  <code class="language-groovy">curl -v -k -X PURGE http://localhost/Public/Home/css/t_navigation.css</code></pre>    <h2><strong>结语</strong></h2>    <p>varnish 是一款内存类型的缓存软件，而非nginx扩展proxy_cache那种物理缓存类型的软件，存取速度比较快,但是也有弊端，重启后所有缓存得重写。不管怎么说，什么架子都适用的场景，要想满足业务需求还是得捣鼓透彻，而我也只是将我想到的给实现出来，毕竟资源和精力都是有限的，也就随便玩玩，诸位看客看看就好，别太认真，知道怎么回事儿就行。</p>    <p> </p>    <p>来自：https://segmentfault.com/a/1190000006853425</p>    <p> </p>