Retrieving memcache value for further processing

Markus Jelsma markus at
Fri Feb 5 13:56:23 MSK 2010

Hello list,

I need some advice on how to solve my use-case. I have a memcache backend with 
some keys and values. Every HTTP request carries a cookie with a SHA1 hash as 
value, this cookie value is also a key in memcache.

I already can retrieve the value and send it as a HTTP response using the 
following configuration:

      # Check if we got the token, a 160bit SHA1 hash
      if ($http_cookie ~* "token=([A-Za-z0-9]{40})")
        # Attempt to retrieve the token from memcache
        set $memc_cmd 'get';
        set $memc_key $http_cookie; # TODO; remove `token=` prefix from key


The question is, how to actually retrieve the value in the configuration for 
further processing. For instance, i would like to put the value in the header 
before i proxy it upstream.

I have tried reading the $memc_value but it seems it does not contain the 
result and that it is only being used for setting or appending a key. If i 
proxy_pass to $memc_value after executing memc_pass, it throws an error, 
telling me the $memc_value was still empty.

In the end i need to perform several small operations on some conditions with 
several memcache values before proxying the entire request upstream. Can i 
even do this with the configuration and memc addon? Or would i need some 
inline perl script to do so?

I use the latest 0.7 Nginx and 0.6 Memc addon.


Markus Jelsma - Technisch Architect - Buyways BV
050-8536620 / 06-50258350

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