Varnish is a state-of-the-art, high-performance HTTP accelerator. It uses the advanced features in Linux 2.6, FreeBSD 6/7 and Solaris 10 to achieve its high performance.

Some of the features include

• A modern design
• VCL – a very flexible configuration language
• Load balance with health checking of backends
• Partial support for ESI
• URL rewriting
• Graceful handling of "dead" backends

INSTALL:

1.download varnish-2.0.4.tar.gz
If you want the last version,you can hit here.

2.unzip varnish
tar zxvf varnish-2.0.4.tar.gz

3.compile varnish
cd varnish-2.0.4
./configure –prefix=/usr/local/varnish –enable-debugging-symbols –enable-developer-warnings –enable-dependency-tracking –enable-tests –enable-diagnostics
make
make install

4.create user:
adduser -s /sbin/nologin www

5.create cache directory &  log file
mkdir -p /var/vcache && chown www.www /var/vcache/
mkdir -p /usr/local/varnish/var/logs && chown www.www /usr/local/varnish/var/logs

6.create config file:
vcl.conf
backend photo1 {
       .host = "10.0.5.33";
       .port = "80";
        .probe = {
                .url = "/guide.php";
                .timeout = 50ms;
                .interval = 5s;
                .window = 10;
                .threshold = 8;
        }
}
backend photo2 {
       .host = "10.0.7.33";
       .port = "80";
        .probe = {
                .url = "/guide.php";
               .timeout = 50ms;
                .interval = 5s;
                .window = 10;
                .threshold = 8;
        }
}
director photo_director round-robin {
    { .backend = photo1; }
    { .backend = photo2; }
}
acl purge {
       "localhost";
       "127.0.0.1";
       "10.0.0.0"/16;
}

sub vcl_recv {
       if (req.request == "PURGE") {
               if (client.ip ~ purge) {
                       purge_url(req.url);
                }
                else{
                        error 200 "Purged";
                }
       }
       if (req.url ~ "\.(gif|jpg|jpeg|bmp)$") {
                unset req.http.cookie;
                unset req.http.authenticate;
                set req.backend = photo_director;
       }
}

sub vcl_hit {
       if (req.request == "PURGE") {
               set obj.ttl = 0s;
               error 200 "Purged.";
       }
        deliver;
}

sub vcl_hash {
    set req.hash += req.url;
    set req.hash += req.http.host;
    set req.hash += req.http.cookie;
    hash;
}

sub vcl_miss {
       if (req.request == "PURGE") {
               error 404 "Not in cache.";
       }
}

sub vcl_fetch {
    if (!obj.cacheable) {
        pass;
    }
    if (obj.http.Pragma ~ "no-cache" || obj.http.Cache-Control ~ "no-cache" || obj.http.Cache-Control ~ "private") {
        pass;
    }
    deliver;
}

7.Optimize the kernel parameters:
net.ipv4.ip_local_port_range = 1024 65536
net.core.rmem_max=16777216
net.core.wmem_max=16777216
net.ipv4.tcp_rmem=4096 87380 16777216
net.ipv4.tcp_wmem=4096 65536 16777216
net.ipv4.tcp_fin_timeout = 3
net.ipv4.tcp_tw_recycle = 1
net.core.netdev_max_backlog = 30000
net.ipv4.tcp_no_metrics_save=1
net.core.somaxconn = 262144
net.ipv4.tcp_syncookies = 0
net.ipv4.tcp_max_orphans = 262144
net.ipv4.tcp_max_syn_backlog = 262144
net.ipv4.tcp_synack_retries = 2
net.ipv4.tcp_syn_retries = 2

8.Start varnish:
#!/bin/sh
ulimit -SHn 51200
/usr/local/varnish/sbin/varnishd -n /var/vcache -f /usr/local/varnish/vcl-php.conf -a 0.0.0.0:80 -s malloc -g www -u www -w 500,10000,15 -T 127.0.0.1:3500 -p client_http11=on -plisten_depth=4096 -p lru_interval=3600  -h classic,500009 -p obj_workspace=2048
/usr/local/varnish/bin/varnishncsa -n /var/vcache -w /usr/local/varnish/var/logs/varnish.log &

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