摘要：以前做網(wǎng)站的時(shí)候遇到了網(wǎng)站的訪(fǎng)問(wèn)量很大，而導(dǎo)致后端處理程序響應(yīng)超時(shí)而導(dǎo)致的一些問(wèn)題。下面我想介紹一下的使用技巧準(zhǔn)備嚴(yán)格來(lái)說(shuō)是可以當(dāng)作一個(gè)代理服務(wù)器的軟件，直接將請(qǐng)求轉(zhuǎn)發(fā)到然后交給處理會(huì)獲取經(jīng)過(guò)處理后的數(shù)據(jù)最后返回給瀏覽器。

以前做網(wǎng)站的時(shí)候遇到了網(wǎng)站的訪(fǎng)問(wèn)量很大，而導(dǎo)致后端處理程序響應(yīng)超時(shí)而導(dǎo)致的一些問(wèn)題。當(dāng)時(shí)采用的架構(gòu)是nginx+php-fastcgi，同事想到了用nginx-proxycache來(lái)做頁(yè)面緩存，效果也還行。下面我想介紹一下varnish的使用技巧

varnish嚴(yán)格來(lái)說(shuō)是可以當(dāng)作一個(gè)代理服務(wù)器的軟件，直接將HTTP請(qǐng)求轉(zhuǎn)發(fā)到php-cgi,然后交給php處理,varnish會(huì)獲取經(jīng)過(guò)php處理后的數(shù)據(jù),最后返回給瀏覽器。如圖

但是，現(xiàn)在php-fastcgi已經(jīng)被逐漸淘汰了，也就是說(shuō)我們一般情況下不會(huì)使用php-fastcgi，那么我們不能直接將varnish與php組合，因?yàn)閜hp-fpm的交互方式為socket，而不再是監(jiān)聽(tīng)本機(jī)的9000端口
所以我們必須找一個(gè)的媒介,連接varnish和php-fpm,nginx可以扮演這個(gè)媒介,如下圖：

那么問(wèn)題來(lái)了，根據(jù)研究發(fā)現(xiàn)，varnish處理http請(qǐng)求不如nginx那么高效。所以如果我們讓nginx做前鋒，這樣就更完美了。那我們需要怎么才能達(dá)到這個(gè)目的呢，下面我們來(lái)整理一下流程

下面就來(lái)實(shí)現(xiàn)一下圖三的架構(gòu)吧。
事先需要準(zhǔn)備nginx,varnish,php-fpm,php這些軟件，OS是ubuntu，所有軟件都可以用apt-get install來(lái)安裝，不了解包名全稱(chēng)的話(huà)可以先apt-get update，更新一下源，然后再用apt-cache search xxx來(lái)查找軟件包名

安裝完varnish后，可以使用service varnish回車(chē)，查看可操作選項(xiàng)* Usage: /etc/init.d/varnish {start|stop|restart|reload|force-reload|configtest},一般安裝完畢后，系統(tǒng)會(huì)自動(dòng)啟動(dòng)varnish的,nginx也是一樣,便不贅述了

安裝完所需的軟件后，下面需要配置這些軟件，來(lái)實(shí)現(xiàn)這個(gè)架構(gòu)

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 需要安裝nginx-extras才能定義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瀏覽器訪(fǎng)問(wèn)查看請(qǐng)求頭

我們?cè)偈褂胏url,在服務(wù)器上執(zhí)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

發(fā)現(xiàn)有輸出內(nèi)容。
然后，反選disable cache

然后在服務(wù)器上執(zhí)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

發(fā)現(xiàn)只返回了頭部信息，然而沒(méi)有內(nèi)容返回

然后我們比較兩個(gè)命令 發(fā)現(xiàn)區(qū)別就在-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這串字符對(duì)應(yīng)的是服務(wù)器響應(yīng)給瀏覽器的ETag部分的內(nèi)容，然后我們修改一下部分的內(nèi)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

在服務(wù)器端執(zhí)行一下。發(fā)現(xiàn)有內(nèi)容返回，所以這個(gè)ETag相當(dāng)于token，它不是由nginx隨便生成的，且跟請(qǐng)求鏈接應(yīng)是一一對(duì)應(yīng)的，用來(lái)標(biāo)識(shí)緩存的,當(dāng)服務(wù)器返回的狀態(tài)為304的時(shí)候,這時(shí)候我們?yōu)g覽器會(huì)直接找到本地的緩存數(shù)據(jù)

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;
}

用瀏覽器查看響應(yīng)頭

發(fā)現(xiàn)X-Cache:MISS from 192.168.99.1.這表示緩存未命中，然后我們刷新X-Cache:HIT from 192.168.99.1，這時(shí)候發(fā)現(xiàn)已經(jīng)命中了。

對(duì)于已經(jīng)命中的資源文件，我們?nèi)绻麑⑵鋭h除會(huì)出現(xiàn)什么效果呢，答案是，其依然可以訪(fǎng)問(wèn)，除非重啟或者將緩存清除
但是對(duì)PURGE顯然是不對(duì)外公開(kāi)的,以下是服務(wù)器端用curl清除varnish緩存的命令

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

varnish是一款內(nèi)存類(lèi)型的緩存軟件，而非nginx擴(kuò)展proxy_cache那種物理緩存類(lèi)型的軟件，存取速度比較快,但是也有弊端，重啟后所有緩存得重寫(xiě)。不管怎么說(shuō)，什么架子都適用的場(chǎng)景，要想滿(mǎn)足業(yè)務(wù)需求還是得搗鼓透徹，而我也只是將我想到的給實(shí)現(xiàn)出來(lái)，畢竟資源和精力都是有限的，也就隨便玩玩，諸位看客看看就好，別太認(rèn)真，知道怎么回事兒就行。