haproxy需要搭建双机热备，必须要有冗余

    keepalived：虚拟ip
    keepalived必须安装在haproxy容器内
    安装keepalived：
    apt-get update
    apt-get install keepalived
    修改配置文件/etc/keepalived/keepalived.conf

    docker pull haproxy

    创建haproxy的配置文件：

    touch /home/soft/haproxy.cfg

    创建haproxy容器：
    docker run -it -d -p 4001:9999 -p 4002:3306 -v /home/soft/haproxy:/usr/local/etc/haproxy
    —name h1 —privileged —net=net1 haproxy1
    进入容器，指定一下配置文件路径：
    docker exec h1 -it bash
    haproxy -f /usr/local/etc/haproxy/haproxy.cfg
    在数据库上创建haproxy账号，以便haproxy进行检查：
    create user ‘haproxy’@’%’ identified by ‘ ‘;