Correct way to do redirect

[Igor Sysoev]

On Sat, Aug 30, 2008 at 11:10:25PM +0700, Chris Savery wrote:

> I expected you would know the correct or optimal way to do this.
> After posting the question I did more reading and found out that rewrite 
> will redirect when the rule give http as start of the result. That was 
> what I didn't know before.

Yes, you may use

rewrite  ...  http://...;
or
rewrite  ...  ...   redirect;

> After playing around I found that loading the smallest geo table I could 
> make from the country database (converted to continent regions) pushed 
> the footprint size of nginx up from about 4MB to over 11 MB. I wasn't 
> too happy with wasting so much memory just to lookup ips.  I'm exploring 
> now possible use of PowerDNS with geo backend to do geo-direction at the 
> DNS level. I'd be happier with using a database lookup and saving memory 
> even it means it's a bit slower since I only do this mapping once per 
> visit.

I think geo-aware DNS is the best choice, notwithstanding to memory footprint.

> I don't see any nginx module to do mysql queries or perhaps sqlite. 
> Something like that could work I think. I have mysql running anyway and 
> can't get away from having it swallow a chunk of memory. Oh well, I 
> wasn't running my own dns servers but probably should and in that case 
> it would be little overhead to do it there. Still tinkering with how to 
> do this in a light memory environment.

I have draft mysql module that can login to mysql server, send query, and
get result, but can not parse it.

As to memory overhead, these extra 5M are shared on the copy-on-write basis
between nginx workers. As nginx never write there while processing requests,
these 5M stay shared. I do not think that in modern world 5M is large memory
footprint, it seems that 128G will become usual hardware in near future:
http://www.mysqlperformanceblog.com/2008/08/04/128gb-or-ram-finally-got-cheap/

BTW, probably you may optimize your geo networks if you did simple GeoIP
line by line mapping. You may try to compress networks like this:

192.168.0.0/24   NA;
192.168.1.0/24   NA;

to

192.168.0.0/23   NA;

> Chris :)
> 
> Igor Sysoev wrote:
> >On Sat, Aug 30, 2008 at 05:28:25AM +0700, Chris Savery wrote:
> >
> >  
> >>I'd like to do a geo based redirect. Users who initially hit my site 
> >>would be given an IP round robin from the  DNS servers. Then each node 
> >>would test the ip and decide if it would be better to redirect to the 
> >>closer node. Only doing this for index.php, eg.
> >>
> >>http {
> >>...
> >>   geo $region {
> >>       default NA;
> >>       include georegions.conf;
> >>       }
> >>...
> >>
> >>server {
> >>...
> >>          location ~ ^/index.php {
> >>              if ($region = NA)
> >>--> what to write here to redirect to other IP?
> >>         }
> >>       location ~ \.php$ { fastcgi_pass 127.0.0.1:9000; include 
> >>fastcgi_params; }
> >>   }
> >>... other servers...
> >>    
> >
> >First it's better to use more effective location:
> >
> >-           location ~ ^/index.php {
> >+           location = /index.php {
> >
> >
> >Or you may do it for "/" only:
> >
> >            location = / {
> >
> >As to redirect, I think it's better to use something like this:
> >
> >    geo $region  {
> >        default  "";
> >        include  georegions.conf;
> >    }
> >
> >    server {
> >         location = /index.php {
> >
> >             if ($region) {
> >                 rewrite  ^   http://$region/index.php;
> >             }
> >
> >             fastcgi_pass 127.0.0.1:9000;
> >             ...
> >         }
> >
> >The georegions.conf is site specific, i.e, for NA site:
> >
> >     x.x.x.x/x   "";                # NA net
> >     x.x.x.x/x   eu.domain.com;     # EU net
> >     x.x.x.x/x   as.domain.com;     # AS net
> >
> >for EU site:
> >
> >     x.x.x.x/x   na.domain.com;     # NA net
> >     x.x.x.x/x   "";                # EU net
> >     x.x.x.x/x   as.domain.com;     # AS net
> >
> >
> >  

-- 
Igor Sysoev
http://sysoev.ru/en/