How to extract and decode base64 parameter in Varnish VCL

Question

In order to invalidate the cache, I'm encoding an url the following way:

$clean_url = base64_encode( $url );

http://url_of_the_varnish_host_to_clean/clean/url?v=$clean_url

I would like to catch this url to clean and decode it in my vcl file. I catch the request this way:

if (req.url ~ "^/clean/url?v=")

But I have no idea how to catch the parameter and decode it.

score 0 · Accepted Answer · answered Mar 27 '17 at 15:55

0

You will at very least need vmod_digest which provides digest.base64_decode function.

Also, your regex is a bit wrong, should be:

if (req.url ~ "^/clean/url\?v=")

That said, why does your invalidation logic has to be so complex? Why not do it standard way - i.e. check against matches of purger IP against defined ACL and invalidate the URL of PURGE request (not parameter).

answered Mar 27 '17 at 15:55

Danila Vershinin

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The problem here is that we use varnish 3.0.2 and vmod_digest requires 4.2 – Vincent Teyssier Mar 27 '17 at 15:57
The reason we use this system is that we can also invalidate hosts or specific parameters using host?v= or parameter?v= – Vincent Teyssier Mar 27 '17 at 15:59
Well, I don't really understand what you can invalidate using your method that you cannot invalidate using the standard one. More examples?) – Danila Vershinin Mar 27 '17 at 16:03

How to extract and decode base64 parameter in Varnish VCL

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