backend和frontend分开配置，可以配置不同端口，比如一个用listen 8000，一个listen 8080，也可以配置不同域名，比如一个server_name www.backend.com，一个server_name www.frontend.com，生产环境中如果需要用到不同子域名，只需要配置不同的server_name，可以都使用80端口。具体例子如下(使用php-fpm)：

#backend配置
server {
    charset utf-8;
    client_max_body_size 128M;

    listen 8000; ## listen for ipv4
    #listen [::]:80 default_server ipv6only=on; ## listen for ipv6

    server_name www.backend.com;
    root        /var/www/yii-test/backend/web;
    index       index.php;


    access_log  /var/www/yii-test/access.backend.log main;
    error_log   /var/www/yii-test/error.backend.log;

    location / {
        # Redirect everything that isn't a real file to index.php
        try_files $uri $uri/ /index.php?$args;
    }        

    location ~ \.php$ {
        include fastcgi.conf;
        fastcgi_pass   127.0.0.1:9000;
        #fastcgi_pass unix:/var/run/php5-fpm.sock;
        try_files $uri =404;
    }
    
    error_page 404 /404.html;

    location ~ /\.(ht|svn|git) {
        deny all;
    }
}

#frontend配置
server {
    charset utf-8;
    client_max_body_size 128M;

    listen 8080; ## listen for ipv4
    #listen [::]:80 default_server ipv6only=on; ## listen for ipv6

    server_name www.frontend.com;
    root        /var/www/yii-test/backend/web;
    index       index.php;


    access_log  /var/www/yii-test/access.frontend.log main;
    error_log   /var/www/yii-test/error.frontend.log;

    location / {
        # Redirect everything that isn't a real file to index.php
        try_files $uri $uri/ /index.php?$args;
    }        

    location ~ \.php$ {
        include fastcgi.conf;
        fastcgi_pass   127.0.0.1:9000;
        #fastcgi_pass unix:/var/run/php5-fpm.sock;
        try_files $uri =404;
    }
    
    error_page 404 /404.html;

    location ~ /\.(ht|svn|git) {
        deny all;
    }
}