Dynamic Redirects

[Harmer, Sean]

Ezra - Thank you.  That is very helpful.

It brings up another question:  Once the match has been made in redis, is
there a way to modify or append data to the User-Agent or HTTP HEADER?

Thanks again,
Sean



On Wed, Apr 7, 2010 at 3:30 PM, Ezra Zygmuntowicz <ezmobius at gmail.com>wrote:

>
> On Apr 7, 2010, at 12:09 PM, Harmer, Sean wrote:
>
> > NGINX Team,
> >
> > Is there a way to capture the User-Agent from an HTTP Header, then query
> a database for that User-Agent, then based on the result of the database
> query, transparently route the request to an appropriate server?
> >
> > Thanks,
> > Sean
>
>
>
> Sean-
>
>
>        Here is one way to do what you want, you will need to use redis as
> the database to lookup your backend with. You will need to compile nginx
> with two additional modules:
>
> http://wiki.nginx.org/NginxHttpRedis
> http://www.grid.net.ru/nginx/eval.en.html
>
>        Once you have both of those module compiled into your nginx you can
> use a config file like this:
>
> worker_processes  1;
> user root root;
> events {
>   worker_connections  1024;
> }
>
> http {
>   include       mime.types;
>   default_type  application/octet-stream;
>
>   sendfile        on;
>
>   log_format main '$remote_addr - $remote_user [$time_local] '
>                   '"$request" $status $body_bytes_sent "$http_referer" '
>                   '"$http_user_agent" "$http_x_forwarded_for"';
>
>   keepalive_timeout  65;
>
>   server {
>       listen       80;
>       server_name  _;
>
>
>       access_log /var/log/nginx/redis.access.log main;
>
>       error_log /var/log/nginx/redis.error.log notice;
>
>       location / {
>               eval_escalate on;
>               eval $answer {
>                       set $redis_key  "$http_user_agent";
>                       set $redis_db   "0";
>                       redis_pass      127.0.0.1:6379;
>               }
>               proxy_pass $answer;
>
>       }
>   }
> }
>
>
>
> Then in redis you will need to store key value pairs mapping the
> $http_user_agent to the server:port combo that should serve that user agent
> type:
>
> redis.set "some-user-agent", "http://192.168.0.1:80"
>
>
> Then when a request comes into the nginx server and has a  $http_user_agent
> value of "some-user-agent", redis will return http://192.168.0.1:80 and
> then nginx will proxy_pass to the particular server.
>
>
> Hope this helps point you in the right direction.
>
>
> Cheers-
>
> Ezra Zygmuntowicz
> ez at engineyard.com
>
>
>
>
> _______________________________________________
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> http://nginx.org/mailman/listinfo/nginx
>



-- 
Sean Harmer
seanharmer at gmail.com
703.957.9272
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