{{tag>nginx proxy}}

====== Example of redirect and rewrites ======
===== Redirect root path =====

Redirect from example.com to example.com/it first then to some proxy app. 

This will preserve any URI after example.com, for example 

//example.com/images/image1.png// 

will become 

example.com/**it**/images/image1.png

The option with using //return// directive is faster.

<code nginx>
upstream ups {
    server 127.0.0.1:3010 fail_timeout=10s max_fails=3;
}

server {
    listen 80;
    server_name example.com;

    access_log /var/log/nginx/ups_access.log;
    error_log /var/log/nginx/ups_error.log notice;

    location / {    
        return 301 /it$request_uri;
        
        # alternative using rewrite
        # rewrite ^/?(.*?)$ http://$host/it/$1 break;
        # rewrite_log on;
    }
    

    location /it {
        proxy_pass http://ups;
        proxy_set_header Host $host;
    }
}

</code>

You can check the rewrite messages in specified error log.

===== Redirect based on browser's Accept-Language header that is sent =====
server conf:
<code nginx>
   location / {
        return 301 /$lang/$request_uri;     
    }

    location /it {
        proxy_pass http://ups;
        proxy_set_header Host $host;
    }

    location /en {
        proxy_pass http://127.0.0.1:3000/;
        proxy_set_header Host $host;
    }

</code>

In http context add the mapping for ''$lang'', e.g.
<code nginx>

http {
        ...
        
        map $http_accept_language $lang {
                default en;
                ~it it;
                ~es es;
                ~fr fr;
        }
        
        ...

}
</code>

===== Rewrite uppercase to lowercase =====
Install perl module first:

  apt install nginx-module-perl

Enable it in //nginx.conf// near top of file, outside of any section
  load_module "modules/ngx_http_perl_module.so";

Create perl rewrite function inside //http// section:
<code nginx>
# Include the perl module
perl_modules perl/lib;

# rewrite function from upper to lowercase
perl_set $uri_lowercase 'sub {
  my $r = shift;
  my $uri = $r->uri;
  $uri = lc($uri);
  return $uri;
}';
</code>

Use it in site configuration, maybe put it at end of file to not interfere with other routes (test this for your own setup)
<code nginx>
# if the path contains uppercase characters,
# rewrite to lowercase
location ~ [A-Z] {
   rewrite ^(.*)$ $scheme://$host$uri_lowercase;
}
</code>

====== Tested on ======
  * Debian 11
  * nginx/1.23.1

====== See also ======
  * [[wiki:nginx_troubleshooting|Nginx troubleshooting]]
  * [[wiki:redirect_another_site_query_parameter_nginx|Redirect to another site from query parameter in nginx]]
====== References ======
  * https://stackoverflow.com/questions/35949123/nginx-rewrite-root-url-with-language-suffix
  * https://serverfault.com/questions/407028/nginx-rewrite-or-return-for-redirection