docker: Cannot find a valid baseurl for repo: base/7/x86_64

$ cat Dockerfile
FROM centos:7
USER root
RUN yum -y install wget
...

执行docker build -t gerrylon/vflow:0.1 .

报错:

…
Cannot find a valid baseurl for repo: base/7/x86_64
…

后来这样:docker build --network=host -t gerrylon/vflow:0.1 .就可以了.

不知道有没有别的方法呢?

欢迎补充指正!