nginx 子域名代理

server {
    ...
    set $subdomain /www;
    if ( $host ~* (\b(?!www\b)\w+)\.\w+\.\w+ ) {
        set $subdomain /$1;
    }

    location / {
    proxy_set_header X-Real-IP $remote_addr;
    if ( $subdomain = "/sd" ) {
        proxy_pass http://www.bitmap.cc:8090;
        break;
    }
        root   /mnt/html$subdomain;
        index  index.html index.htm;
    }
    ...
}