Logged-in users

Tim Kientzle tim at metaweb.com
Wed Nov 26 22:14:36 CET 2008

Another approach is to simply use a small bit of Javascript.  It's
easy to test for the existence of the cookie in Javascript and
set that text conditionally.

Then you have only one copy of the page to be cached.

The problem with the approach you've outlined here is
that other downstream caches won't understand the difference
(although most will simply refuse to cache any responses
if the request had a cookie header).  Whereas the Javascript
approach also allows downstream caches to cache everything


On Nov 26, 2008, at 12:31 PM, Miles wrote:

> Miles wrote:
>> Hi,
>> I have a site where users can log in.  This sets a cookie with their
>> encrypted login details, so they can be authenticated.  There are a
>> small number of pages which are user-specific ("change your details"
>> forms, etc), and these are set not to cache.
>> When a user is logged in, a message is shown at the top of the page  
>> "You
>> are now logged in".  However, nothing on the page depends on the
>> individual user.
>> My question is, how can I organise the cache to have the most cache
>> hits, given that there are effectively two versions of each page -  
>> one
>> for logged in users, and one for anonymous users.  I want to
>> specifically avoid each user having their own version of the page  
>> stored
>> in the cache.
>> Thanks in advance for any wisdom anyone can share!
>> Miles
> Thanks to everyone who suggested using ESI - I may have to use this,  
> but
> would quite like to avoid it, as it's useful to be able to run the app
> without varnish in front for development/testing.
> I wondered whether it was possible to use vcl_hash for my purposes, as
> follows:
> sub vcl_hash {
>    //hash the object with url+host
>    set req.hash += req.url;
>    set req.hash += req.http.host;
>    # see if the user has a cookie to indicate they are logged in
>    if req.http.cookie ~ '__ac=':
>       set req.hash += 'authenticated';
>    else:
>       set req.hash += 'anonymous'
>    hash;
> }
> Would this give me the two representations that I require for each  
> page
> - or am I going down a route that will turn out bad?!  I couldn't find
> much information about vcl_hash, so I'm not sure if I'm barking up the
> wrong tree or not...
> Regards,
> Miles
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