在用docker pull ubuntu:20.04时遇到如下错误：
$ docker pull ubuntu:20.04
Error response from daemon:Get "https://registry-1.docker.io/v2/": net/http: request canceled while waiting for connection (Client.Timeout exceeded while awaiting headers)
似乎是网络的问题，找了很多方法都解决不了，于是想绕过docker pull，直接下载image, 然后本地load.
python文件docker_pull_image.py放在这里
python docker_pull.py ubuntu:20.04 -o ubuntu_20_04.tar
Multi-architecture image detected. Selecting appropriate manifest...
Total uncompressed size of all layers: 24.77 MB
Layer 0 verified successfully.
ubuntu:20.04 image (arm64) downloaded and saved as ubuntu_20_04.tar
Compressed tar size: 24.79 MB
Load the image using: docker load -i ubuntu_20_04.tar
再试一下hello-world
$ python docker_pull_image.py hello-world
No tag specified, using latest tag: latest
Multi-architecture image detected. Selecting appropriate manifest...
Total uncompressed size of all layers: 0.00 MB
Layer 0 verified successfully.
hello-world:latest image (amd64) downloaded and saved as hello-world_latest.tar
Compressed tar size: 0.01 MB
Load the image using: docker load -i hello-world_latest.tar$ docker load -i hello-world_latest.tar
Loaded image: hello-world:latest$ docker run -it hello-worldHello from Docker!
This message shows that your installation appears to be working correctly.
