Nginx 代理 varnish 的姿势

摘要：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。下面我想介绍一下的使用技巧准备严格来说是可以当作一个代理服务器的软件，直接将请求转发到然后交给处理会获取经过处理后的数据最后返回给浏览器。

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

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

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
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：

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

下面就来实现一下图三的架构吧。
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

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

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

vi /etc/nginx/nginx.conf

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/*;  
}

vi /etc/nginx/sites-available/default

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;
    }
}

vi /etc/varnish/default.vcl

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");
    }
}

vi /etc/nginx/sites-available/default

#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;
#}

先用chrome浏览器访问查看请求头

我们再使用curl,在服务器上执行以下命令

 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

发现有输出内容。
然后，反选disable cache

然后在服务器上执行以下命令

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

发现只返回了头部信息，然而没有内容返回

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""

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

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

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

vi /etc/nginx/sites-available/default

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;
}

用浏览器查看响应头

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。

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
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

curl -v -k -X PURGE http://localhost/Public/Home/css/t_navigation.css

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。