进入docker相应容器

sudo docker exec -it ID bash

vim打开配置文件（位置与ubuntu相同）

vim /etc/apt/sources.list

注释掉所有有效内容，然后加入如下内容（参考 https://mirrors.tuna.tsinghua.edu.cn/help/ubuntu/?spm=a2c4e.10696291.0.0.51fa19a4N1S6az）

# 默认注释了源码镜像以提高 apt update 速度，如有需要可自行取消注释

deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic main restricted universe multiverse

# deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic main restricted universe multiverse

deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-updates main restricted universe multiverse

# deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-updates main restricted universe multiverse

deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-backports main restricted universe multiverse

# deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-backports main restricted universe multiverse

deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-security main restricted universe multiverse

# deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-security main restricted universe multiverse

更新看看速度：

sudo apt-get update

sudo apt-get upgrade   (慎用，我的系统因为安装了docker-nvidia,中断了升级)