variable variables?

[agentzh]

On Mon, Jan 2, 2012 at 11:40 PM, Karoly Negyesi <chx1975 at gmail.com> wrote:
> Hi,
>
> Nginx provides the value of the cookie "foo" in $cookie_foo . Is it
> possible to read "foo" from the URL? In PHP you would use two dollar
> signs for this kind of indirection.
>

Well, it is trivial with ngx_lua's set_by_lua config directive:

    location /blah {
        set_by_lua $arg_value
            'local arg_name = ngx.var.cookie_foo
             return ngx.var["arg_" .. arg_name]';

        # reference $arg_value in later phase config directives here...
    }

See the documentation for details:

    http://wiki.nginx.org/HttpLuaModule#set_by_lua

Regards,
-agentzh