I am trying to set up a private cluster in the Google Kubernetes Engine, and as the nodes don't have access to the public internet, they cannot pull from Docker Hub.
As described here, the resolution is to configure the Docker daemon to fetch also from Google's internal mirror, but I have not found an option to do so when setting the cluster, and as the nodes are private, I don't expect to have access to do that manually.
What is the best way (if any) to configure the nodes to enable that?
Private cluster by default do not have access to public internet and it is not possible to configure your Docker daemon to fetch images from Container Registry's Docker Hub mirror while creating cluster. You can use either CLI or Docker UI, are the best way to configure Docker daemon.
As far as I am aware of, configuring Docker daemon is the only option.