Google到了一个网页，里面都是解决方法
https://askubuntu.com/questions/123072/ssh-automatically-accept-keys/553308
我觉得最简单的解决方法是：
With 18.04, there’s a new possibility: StrictHostKeyChecking=no. From man 5 ssh_config:
If this flag is set to “accept-new” then ssh will automatically
add new host keys to the user known hosts files, but will not
permit connections to hosts with changed host keys. If this flag
is set to “no” or “off”, ssh will automatically add new host keys
to the user known hosts files and allow connections to hosts with
changed hostkeys to proceed, subject to some restrictions.
(base) root@hadoop-master:~# locate ssh_config
/etc/ssh/ssh_config
/usr/share/man/man5/ssh_config.5.gz
在Dockerfile中：
echo "StrictHostKeyChecking=no" >> /etc/ssh/ssh_config
