云服务器使用sudo apt-get update 失败的原因及解决方法（unubtu下）

今天在使用云服务器安装东西的时候，更新软件包，突然发现失败了，出现了以下情况：

苦苦寻找原因，各种答案，都没能成功解决问题，后来把出错的英语翻译了一下，大概的意思就是，获取包返回失败，后来想想是不是DNS的问题,然后重点来了

我输入：cat /etc/resolv.conf

root@whcckj:~# cat /etc/resolv.conf

# This file is managed by man:systemd-resolved(8). Do not edit.

#

# This is a dynamic resolv.conf file for connecting local clients to the

# internal DNS stub resolver of systemd-resolved. This file lists all

# configured search domains.

#

# Run "systemd-resolve --status" to see details about the uplink DNS servers

# currently in use.

#

# Third party programs must not access this file directly, but only through the

# symlink at /etc/resolv.conf. To manage man:resolv.conf(5) in a different way,

# replace this symlink by a static file or a different symlink.

#

# See man:systemd-resolved.service(8) for details about the supported modes of

# operation for /etc/resolv.conf.

nameserver 127.0.0.53

search openstacklocal

标蓝的地方就是问题所在，于是我们修改这个标蓝的地方

vi /etc/resolv.conf

改成 namesever 8.8.8.8 

保存退出（先按下ESC,在输入：wq，回车搞定），然后使用sudo apt-get update