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Varnish Cache Redirector

This configuration example of Varnish will process inbound requests and use permanent redirects to force clients to get the canonical URI. For example, forcing a specific hostname by stripping the www. (which is the right way to do things, www. is so 2000-late). As and example, notice that google.com forces the www. prefix, while twitter.com forces the removal of www. host-prefix.

Removing www.

If a request comes in with the wrong host name, tag it and pass the request to the error handler. This is a good approach for one or two hostnames.

sub vcl_recv {

    if (req.http.host != "domain.tld") {
        error 601 req.url;
    }

    # ...

}

sub vcl_error {

    if (obj.status == 601) {
        set obj.http.location = "http://domain.tld" obj.response;
        set obj.status = 301;
        return (deliver);
    }
}

Forcing www. prefix

This is what Google does,

sub vcl_recv {

    if (req.http.host != "www.domain.tld") {
        error 604 req.url;
    }

    # ...

}

sub vcl_error {

    if (obj.status == 604) {
        set obj.http.location = "http://www.domain.tld" obj.response;
        set obj.status = 301;
        return (deliver);
    }
}

See Also

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