Drupal 7 Nginx configuration for Multi-site Subfolders

Basically, I want to create a structure as follows:

Main site

/var/www/mainsite.com/master/src/

Sub-sites

• /usr/local/subsites/_site1/src/
• /usr/local/subsites/_site2/src/
• /usr/local/subsites/_site3/src/

and these sub-sites should be accessible as follows:

• mainsite.com/site1
• mainsite.com/site2
• mainsite.com/site3

All sites completely separate drupal systems and they all have different databases and sources.

I tired the reverse proxy setup with perusio configuration but it seems that is not working properly, User login does not work and There are some broken links.

Main site configuration

server {
    listen 80; # IPv4

    server_name mainsite.com;
    limit_conn arbeit 32;

    ## Access and error logs.
    access_log /var/log/nginx/mainsite.com_access.log;
    error_log /var/log/nginx/mainsite.com_error.log;

    ## See the blacklist.conf file at the parent dir: /etc/nginx.
    ## Deny access based on the User-Agent header.
    if ($bad_bot) {
        return 444;
    }
    ## Deny access based on the Referer header.
    if ($bad_referer) {
        return 444;
    }

    ## Protection against illegal HTTP methods. Out of the box only HEAD,
    ## GET and POST are allowed.
    if ($not_allowed_method) {
        return 405;
    }

    location /site1/ {

      proxy_pass         http://site1.mainsite.com/;
      proxy_redirect     http://site1.mainsite.com/ http://mainsite.com/site1/;
      proxy_set_header   Host             $host;
      proxy_set_header   X-Real-IP        $remote_addr;
      proxy_set_header   X-Forwarded-For  $proxy_add_x_forwarded_for;

    }

    root /var/www/mainsite.com/master/src/;
    index index.php;

    ## If you're using a Nginx version greater or equal to 1.1.4 then
    ## you can use keep alive connections to the upstream be it
    ## FastCGI or Apache. If that's not the case comment out the line below.
    fastcgi_keep_conn on; # keep alive to the FCGI upstream

    ## Uncomment if you're proxying to Apache for handling PHP.
    #proxy_http_version 1.1; # keep alive to the Apache upstream

    ################################################################
    ### Generic configuration: for most Drupal 7 sites.
    ################################################################
    include apps/drupal/drupal.conf;

    #################################################################
    ### Support for upload progress bar. Configurations differ for
    ### Drupal 6 and Drupal 7.
    #################################################################
    include apps/drupal/drupal_upload_progress.conf;

} # HTTP server

sub-site settings.php

  $base_url = 'http://mainsite.com/site1';
  $conf['reverse_proxy'] = TRUE;
  $conf['reverse_proxy_addresses'] = array('127.0.0.1');

How can I make this work?