Retrieving memcache value for further processing

Server NGINX
1

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

    memc_pass 127.0.0.1:11211;
  }

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.

Regards,

Markus J. - Technisch Architect - Buyways BV
http://www.linkedin.com/in/markus17
050-8536620 / 06-50258350

2

Thanks Mauro!

This looks rather promising! I will try this.

Cheers

you should check the eval module:
Nginx eval module (v 1.0.1)

By the way, why don’t i receive a copy of my own e-mail? I have the
following
setting enabled.
Ordinarily, you will get a copy of every message you post to the list.
If you
don’t want to receive this copy, set this option to No.

Markus J. - Technisch Architect - Buyways BV
http://www.linkedin.com/in/markus17
050-8536620 / 06-50258350

3

you should check the eval module:
http://www.grid.net.ru/nginx/eval.en.html