Varnish使用小结

Varnish使用小结 - [技术笔记]

2009-02-12 | Tag：varnish compress acl purge varnishadm

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http://iyubo.blogbus.com/logs/35085709.html

此日志会随时更新，当然，是随着我的应用积累:)

实现静态文件压缩

Varnish itself does not compress or decompress objects, although that has been on our wish list for quite a while. However, it will operate correctly with backends that support compression.

从官方网站可以得知，Varnish本身并不能提供压缩的功能，但是我们又想要使用压缩，该怎么处理呢？（有关压缩的方面可以参考官方网站http://varnish.projects.linpro.no/wiki/FAQ/Compression）

在vcl_recv中加入如下配置，为Varnish指定压缩算法，提高效率。（Even though there are few possible values for Accept-Encoding, Varnish treats them literally rather than semantically, so even a small difference which makes no difference to the backend can reduce cache efficiency by making Varnish cache too many different versions of an object.）

        if (req.http.Accept-Encoding) {
                if (req.url ~ "\.(jpg|png|gif|gz|tgz|bz2|tbz|mp3|ogg)$") {
                # No point in compressing these
                remove req.http.Accept-Encoding;
                } else if (req.http.Accept-Encoding ~ "gzip") {
                        set req.http.Accept-Encoding = "gzip";
                } else if (req.http.Accept-Encoding ~ "deflate") {
                        set req.http.Accept-Encoding = "deflate";
                } else {
                        # unkown algorithm
                        remove req.http.Accept-Encoding;
                }
        }

在vcl_hash中

sub vcl_hash {
        set req.hash += req.url;
        if (req.http.Accept-Encoding ~ "gzip") {
                set req.hash += "gzip";
        }
        else if (req.http.Accept-Encoding ~ "deflate") {
                set req.hash += "deflate";
        }
        hash;
}

这样就把压缩的工作还是交给后端服务器去做

添加一个Header标识是否命中

sub vcl_deliver {
        if (obj.hits > 0) {
                set resp.http.X-Cache = "HIT";
        } else {
                set resp.http.X-Cache = "MISS";
        }
}

对特定URL进行IP访问限制

如果我们对某些特定的URL只想某些IP能访问，又该怎么办呢？

首先定义允许访问的IP列表

acl permit {
        "10.1.1.5";
        "10.0.2.5";
        "10.10.1.3";
}

然后是针对URL进行访问控制

                if (req.url ~ "/test/.*" && !client.ip ~ permit) {
                        error 403 "Not Allowed.";
                }

对特定URL不缓存

sub vcl_fetch {
    if (req.request == "GET" && req.url ~ "/test/.*") {
        set obj.ttl = 0s;
    }
    else {
        set obj.ttl = 1800s;
    }
   #set    obj.http.X-Varnish-IP = server.ip;
    set    obj.http.Varnish = "Tested by Kevin";
    insert;
}

清除指定缓存内容

我们可以通过varnishadm这个命令从管理端口进行指定缓存的清除

/usr/varnish/bin/varnishadm -T 127.0.0.1:3500 url.purge /test/*

/usr/varnish/bin/varnishadm -T 127.0.0.1:3500 url.purge *$ (清除所有缓存)