varnish的簡單配置

雖然使用nginx和http的時候都可以基於cache模塊使用緩存功能,但當用戶的併發上升到一定等級時,web服務自帶的緩存功能是遠遠不夠的,這時我們就需要一臺專門管理緩存的服務器。varnish是一款開源的緩存服務軟件,相對於squid更加的輕量級。

varnish的程序環境:
/etc/varnish/varnish.params: 配置varnish服務進程的工作特性,例如監聽
的地址和端口,緩存機制;
/etc/varnish/default.vcl:配置各Child/Cache線程的緩存策略;
主程序:
    /usr/sbin/varnishd
CLI interface:
    /usr/bin/varnishadm
VCL配置文件重載程序:
    /usr/sbin/varnish_reload_vcl
varnish的緩存存儲機制( Storage Types):
  -s [name=]type[,options]  
    · malloc[,size]
        內存存儲,[,size]用於定義空間大小;重啓後所有緩存項失效;
    · file[,path[,size[,granularity]]]
        磁盤文件存儲,黑盒;重啓後所有緩存項失效;
    · persistent,path,size
        文件存儲,黑盒;重啓後所有緩存項有效;實驗;

通過yum安裝完varnish後,首先我們來看看varnish.params配置文件

# Varnish environment configuration description. This was derived from
# the old style sysconfig/defaults settings

# Set this to 1 to make systemd reload try to switch VCL without restart.
RELOAD_VCL=1

# Main configuration file. You probably want to change it.
VARNISH_VCL_CONF=/etc/varnish/default.vcl  #指定默認的vcl文件

# Default address and port to bind to. Blank address means all IPv4
# and IPv6 interfaces, otherwise specify a host name, an IPv4 dotted
# quad, or an IPv6 address in brackets.
# VARNISH_LISTEN_ADDRESS=192.168.1.5
VARNISH_LISTEN_PORT=80 #指定監聽的端口

# Admin interface listen address and port
VARNISH_ADMIN_LISTEN_ADDRESS=127.0.0.1 #管理地址
VARNISH_ADMIN_LISTEN_PORT=6082

# Shared secret file for admin interface
VARNISH_SECRET_FILE=/etc/varnish/secret #口令文件

# Backend storage specification, see Storage Types in the varnishd(5)
# man page for details.
VARNISH_STORAGE="file,/var/varnish/cache,256M" #這個是我們主要改的,存儲的位置,方法形式

# User and group for the varnishd worker processes
VARNISH_USER=varnish
VARNISH_GROUP=varnish

# Other options, see the man page varnishd(1)
#DAEMON_OPTS="-p thread_pool_min=5 -p thread_pool_max=500 -p thread_pool_timeout=300"    
varnish程序的選項:
            程序選項:/etc/varnish/varnish.params文件
                -a address[:port][,address[:port][...],默認爲6081端口; 
                -T address[:port],默認爲6082端口;
                -s [name=]type[,options],定義緩存存儲機制;
                -u user
                -g group
                -f config:VCL配置文件;
                -F:運行於前臺;

然後我們使用varnishadm來登陸接口
varnishadm -S /etc/varnish/secret -T 127.0.0.1:6082
登陸進來使用help查看可用的命令

    
            配置文件相關:
                vcl.list 
                vcl.load:裝載,加載並編譯;
                vcl.use:激活;
                vcl.discard:刪除;
                vcl.show [-v] <configname>:查看指定的配置文件的詳細信息;
                
            運行時參數:
                param.show -l:顯示列表;
                param.show <PARAM>
                param.set <PARAM> <VALUE>
                
            緩存存儲:
                storage.list
                
            後端服務器:
                backend.list 

下面我們來介紹下VCL配置文件,裏面的功能是通過一種語言實現的。VCL有多個狀態引擎,狀態之間存在相關性,但狀態引擎彼此間互相隔離;每個狀態引擎可使用return(x)指明關聯至哪個下一級引擎;每個狀態引擎對應於vcl文件中的一個配置段,即爲subroutine。


13920922-f1e8b4fbf6c8b97e.png
image.png
vcl_recv的默認配置:
            
                sub vcl_recv {
                    if (req.method == "PRI") {
                        /* We do not support SPDY or HTTP/2.0 */
                        return (synth(405));
                    }
                    if (req.method != "GET" &&
                    req.method != "HEAD" &&
                    req.method != "PUT" &&
                    req.method != "POST" &&
                    req.method != "TRACE" &&
                    req.method != "OPTIONS" &&
                    req.method != "DELETE") {
                        /* Non-RFC2616 or CONNECT which is weird. */
                        return (pipe);
                    }

                    if (req.method != "GET" && req.method != "HEAD") {
                        /* We only deal with GET and HEAD by default */
                        return (pass);
                    }
                    if (req.http.Authorization || req.http.Cookie) {
                        /* Not cacheable by default */
                        return (pass);
                    }
                        return (hash);
                    }
                }

裏面還有許許多多的變量

變量類型:
            內建變量:
                req.*:request,表示由客戶端發來的請求報文相關;
                    req.http.*
                        req.http.User-Agent, req.http.Referer, ...
                bereq.*:由varnish發往BE主機的httpd請求相關;
                    bereq.http.*
                beresp.*:由BE主機響應給varnish的響應報文相關;
                    beresp.http.*
                resp.*:由varnish響應給client相關;
                obj.*:存儲在緩存空間中的緩存對象的屬性;只讀;
                
                常用變量:
                    bereq.*, req.*:
                        bereq.http.HEADERS
                        bereq.request:請求方法;
                        bereq.url:請求的url;
                        bereq.proto:請求的協議版本;
                        bereq.backend:指明要調用的後端主機;
                        
                        req.http.Cookie:客戶端的請求報文中Cookie首部的值; 
                        req.http.User-Agent ~ "chrome"
                        
                        
                    beresp.*, resp.*:
                        beresp.http.HEADERS
                        beresp.status:響應的狀態碼;
                        reresp.proto:協議版本;
                        beresp.backend.name:BE主機的主機名;
                        beresp.ttl:BE主機響應的內容的餘下的可緩存時長;
                        
                    obj.*
                        obj.hits:此對象從緩存中命中的次數;
                        obj.ttl:對象的ttl值
                        
                    server.*
                        server.ip
                        server.hostname
                    client.*
                        client.ip                   
                
            用戶自定義:
                set 
                unset 

默認的VCL文件

vcl 4.0;

# Default backend definition. Set this to point to your content server.
backend default {
    .host = "192.168.31.201";
    .port = "80";
}

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.
}

sub vcl_backend_response {
    # Happens after we have read the response headers from the backend.
    #
    # Here you clean the response headers, removing silly Set-Cookie headers
    # and other mistakes your backend does.
}

sub vcl_deliver {
    # Happens when we have all the pieces we need, and are about to send the
    # response to the client.
    #
    # You can do acc
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