Why I did it
The docker storage driver vfs is not a good option for build, it uses the “deep copy” when building a new layer, leads to lower performance and more space used on disk than other storage drivers.
A better docker storage driver is the default one overlay2, it is a modern union filesystem.
Why I did it
docker hub will limit the pull rate.
Use ACR instead to pull debian related docker image.
How I did it
Set DEFAULT_CONTAINER_REGISTRY in pipeline.