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Daniel C. Sobral
Asked: 2013-05-31 08:30:17 +0800 CST

Conditional variable setting in nginx

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I'm writing an nginx configuration that requires a proxy, and I need to original ip address. Nginx's HttpProxyModule's $proxy_add_x_forwarded_for variable seems perfectly adequate for the task, except that my Nginx is behind a load balance that sets not X-Forwarded-For, but X-Cluster-Client-Ip.

Now, one possibility would be using

set X-Forwarded-For $http_x_cluster_client_ip,$proxy_add_x_forwarded_for

but sometimes there are direct accesses to the server, which would leave a leading comma in the header. I thought about using if, but that scenario falls right in the middle of the cases where if is problematic to use.

Note that, because the client might have been proxied, I do want to preserve any data present in the X-Forwarded-For header, if one exists, in addition to passing data from X-Cluster-Client-Ip.

Any alternatives?

nginx

1 Answers

  1. You can use the nginx HttpRealipModule to filter accesses from the Loadbalancer instead:

    set_real_ip_from   192.168.0.1;
real_ip_header     X-Cluster-Client-Ip;

    http://wiki.nginx.org/HttpRealipModule

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