Docker build ubuntu 沒法執行 apt-get update

之前的Dockerfile從新build時出現沒法執行 apt-get update，在宿主機是能夠的。

找到個攻略，docker build加上--network=host參數，臨時解決！

第二種方法：

the problem was with Internet connection, as mine connection is at enterprise level and because of that It was unable to execute apt-get update command. Solution worked for me is :

    find your DNS server address using cat /etc/resolv.conf

    Open Docker confg file and uncomment DOCKER_OPTS and add your DNS server over there

Docker config file : sudo gedit /etc/default/docker

參考：

• https://www.v2ex.com/t/575898
• https://askubuntu.com/questions/1167080/unable-to-update-ubuntu-docker-container-using-apt-get-update
• https://www.cnblogs.com/surplus/p/11580707.html