Docker中Debian9安装Keepalived

在学习数据库集群的负载均衡时，有需要通过Docker镜像安装一个Haproxy的容器，然后再在这个容器中安装Keepalived，于是就遇到了下面这样一个坑。

正常部署是走如下两步：

apt-get update
apt-get install keepalived

但由于一些特殊原因，apt-get update这个命令执行起来速度特别慢，于是需要切换源。步骤是这样的：

1、找到需要配置的内容：

deb http://mirrors.aliyun.com/debian stretch main contrib non-free
deb-src http://mirrors.aliyun.com/debian stretch main contrib non-free
deb http://mirrors.aliyun.com/debian stretch-updates main contrib non-free
deb-src http://mirrors.aliyun.com/debian stretch-updates main contrib non-free
deb http://mirrors.aliyun.com/debian-security stretch/updates main contrib non-free
deb-src http://mirrors.aliyun.com/debian-security stretch/updates main contrib non-free

2、/etc/apt/sources.list 的内容换成步骤1中找到的内容。

问题就出在这儿，因为是Debian系统，里面既没有vi，也没有vim，修改不了sources.list文件内容。在网上找了一下解决办法，有的回答说，先安装vim，可当我输入apt-get install vim，终端上显示：

Reading package lists... Done
Building dependency tree       
Reading state information... Done
E: Unable to locate package

相当于要先执行一下apt-get update，才能执行apt-get install，坑爹。。

继续在网上找解决方法，发现可以用echo命令解决这个问题。

#先备份sources.list
mv /etc/apt/sources.list /etc/apt/sources.list.bak
#再编辑sources.list
echo "deb http://mirrors.aliyun.com/debian stretch main contrib non-free" >> /etc/apt/sources.list
echo "deb-src http://mirrors.aliyun.com/debian stretch main contrib non-free" >> /etc/apt/sources.list
echo "deb http://mirrors.aliyun.com/debian stretch-updates main contrib non-free" >> /etc/apt/sources.list
echo "deb-src http://mirrors.aliyun.com/debian stretch-updates main contrib non-free" >> /etc/apt/sources.list
echo "deb http://mirrors.aliyun.com/debian-security stretch/updates main contrib non-free" >> /etc/apt/sources.list
echo "deb-src http://mirrors.aliyun.com/debian-security stretch/updates main contrib non-free" >> /etc/apt/sources.list

然后我再执行apt-get update，问题解决~