How do I make Varnish purge all variants of a URL?

5
votes

Varnish 2.1: I'm trying to use http PURGE to get Varnish to renew one cached URL.

While testing, I would get results that seemed strange until I read this bit in the documentation: "If there are several variants of the same URL in the cache however, only the matching variant will be purged. To purge a gzip variant of the same page the request would have to look like this:"

So now if I do these two commands:

curl -I http://example.com/my-url
curl -X PURGE http://example.com/my-url

I get back a 200 Purged response.

And if I do these two:

curl -I http://example.com/my-url -H "Accept-Encoding: gzip"
curl -X PURGE http://example.com/my-url -H "Accept-Encoding: gzip"

I also get a 200 Purged.

Now if I try:

curl -I http://example.com/my-url -H "Accept-Encoding: deflate"

I get back headers that indicate that the Content-Encoding: is "text/html;charset=utf-8", and it has age in the cache. That seems to indicate that "deflate" isn't being supported by my app, which is probably correct.

The page also has an Age: header indicating that it's being cached.

Now how do I purge that? (Am I asking a moot question?)

All of these attempts return "404 Not in cache":

curl -X PURGE http://example.com/my-url -H "Accept-Encoding: deflate"
curl -X PURGE http://example.com/my-url -H "Accept-Encoding: text/html;charset=utf-8"
curl -X PURGE http://example.com/my-url -H "Accept-Encoding: text/html"

Is there a magic way to purge all of the variants of a URL?

2
varnish
Does your VCL have entries for both vlc_hit and vlc_miss? – favoretti
Umm, let me rephrase, pardon me asking an improper question. I meant to ask whether it has purge entries for both hit and miss. – favoretti
Yes, and I can see them both executing correctly in the first and second examples. I've seen both Purged and "Not in cache" results from those routines on the PURGE call. – Mojo
Out of curiosity.. What would you get if you try curl -I http://example.com/my-url -H "Accept-Encoding: gzip", followed by curl -X PURGE http://example.com/my-url? I'm not sure why it doesn't work in your example, other than response cached wasn't a page, but from what I understand, just purging a url should purge all instances of it. That being said, my varnish experience is rather non-extensive. – favoretti
That test returns "404 not in cache". If I repeat the purge and add -H "Accept-Encoding: gzip" it returns "200 Purged." That's pretty much the gist of my problem -- how to purge all variations of a cached page. – Mojo

2 Answers

7
votes

Aha, by applying some google-fu, I stumbled on a forum post, that suggests the following:

purge("req.url ~ ^" req.url "$");

i.e. using a regexp behind purge, to handle all Accept-Encoding headers.

More info here: http://www.gossamer-threads.com/lists/varnish/misc/15124

.. which means you need to modify your VCL though.

3
votes

I think this is what u need:

acl purge {
        "localhost";
        "192.168.55.0"/24;
}

sub vcl_recv {
        # allow PURGE from localhost and 192.168.55...

        if (req.request == "PURGE") {
                if (!client.ip ~ purge) {
                        error 405 "Not allowed.";
                }
                return (lookup);
        }
}

sub vcl_hit {
        if (req.request == "PURGE") {
                purge;
                error 200 "Purged.";
        }
}

sub vcl_miss {
        if (req.request == "PURGE") {
                purge;
                error 200 "Purged.";
        }
}