docker pull twice from remote registry

Question

In the latest Docker, I encountered an issue like this.

docker pull mongo:4.0.10
4.0.10: Pulling from library/mongo
f7277927d38a: Pull complete
8d3eac894db4: Downloading
edf72af6d627: Download complete
3e4f86211d23: Download complete
5747135f14d2: Download complete
f56f2c3793f6: Download complete
f8b941527f3a: Download complete
4000e5ef59f4: Download complete
ad518e2379cf: Download complete
919225fc3685: Download complete
45ff8d51e53a: Download complete
4d3342ddfd7b: Download complete
26002f176fca: Download complete
4.0.10: Pulling from library/mongo
f7277927d38a: Pulling fs layer
8d3eac894db4: Pulling fs layer
edf72af6d627: Pulling fs layer

When I pull an image, it will pull it from my registry-mirrors firstly(quickly), then the official hub( I guess, very slow).

but I do not have this problem before.

The docker version I used at the moment(Docker for Windows).

docker -v
Docker version 19.03.13-beta2, build ff3fbc9d55

Update : Occurred again today. Not sure somewhat changed its config then affected Docker. I played Minikube and Kind in these days.

Update: , create an issue moby/moby#41547) , please vote it if you are encountering the same problem.

Answer 1

I have the same issue with you(from china). After my researching, below is the reason why docker will pull twice.

8d3eac894db4: Downloading

This means this file can not get download from your registry-mirrors.

So after time out, docker will pull this mongo image from official docker hub.