根据用户请求不同的域名，调度到不同的后端集群
用户请求www.qingchen.com调度到172.16.1.7:80,172.16.1.8:80
用户请求blog.qingchen.com调度到172.16.1.7:8080,172.16.1.8:8080

#www站点定义(所有web节点配置一致)
cat /etc/nginx/conf.d/www.qingchen.com.conf
server {
    listen 80;
    server_name www.qingchen.com;
    root /www
    location / {
        index index.html
    }
}
echo "www.qingchen.com-->web1" > /www/index.html

#blog站点定义(所有web节点配置一致)
cat /etc/nginx/conf.d/blog.qingchen.com.conf
server {
    listen 8080;
    server_name blog.qingchen.com;
    root /blog
    location / {
        index index.html
    }
}
echo "blog.qingchen.com-->web1" > /blog/index.html

frontend web
    bind *:80
    mode http
    
    # acl规则
    acl www_site hdr(host) -i www.qingchen.net
    acl blog_site hdr(host) -i blog.qingchen.net
    
    # 调用
    use_backend www_cluster if www_site
    use_backend blog_cluster if blog_site 
    default_backend www_cluster

backend www_cluster
    balance roundrobin
    option httpchk HEAD / HTTP/1.1\r\nHost:\ www.qingchen.net
    server 172.16.1.7 172.16.1.7:80 check port 8080 inter 3s rise 2 fall 3
    server 172.16.1.8 172.16.1.8:80 check port 8080 inter 3s rise 2 fall 3

backend blog_cluster
    balance roundrobin
    option httpchk HEAD / HTTP/1.1\r\nHost:\ blog.qingchen.net
    server 172.16.1.7 172.16.1.7:8080 check port 8080 inter 3s rise 2 fall 3
    server 172.16.1.8 172.16.1.8:8080 check port 8080 inter 3s rise 2 fall 3

curl -HHost:www.qingchen.net http://10.0.0.5
curl -HHost:blog.qingchen.net http://10.0.0.5