Network timed out while trying to connect to

あるDockerfileをPULLするところでエラーを吐いていた。

Network timed out while trying to connect to ....

詳細は以下。

$ kohey% docker build -t kohey/kangol .                                                                                             
Sending build context to Docker daemon 15.36 kB
Step 0 : FROM ubuntu
Pulling repository docker.io/library/ubuntu
Network timed out while trying to connect to https://index.docker.io/v1/repositories/library/ubuntu/images. You may want to check your internet connection or if you are behind a proxy.

直した方法としては

docker-machine restart 〇〇
eval "$(docker-machine env ◯◯)"

で直った。。。。