A simple script for moving your entire registry to other.

migrate_docker_registry.sh

#!/bin/bash

# You must be logged in both registries before.

SOURCE_REGISTRY_IMAGES=( 
your.source.registry/namespace1/subnamespace1/image1:tag 
your.source.registry/namespace1/subnamespace1/image2:tag  
)

DESTINATION_REGISTRY_NAMESPACE="your.destination.registry/namespace/subnamespace"

for i in ${SOURCE_REGISTRY_IMAGES[*]}; do 
    image=$(echo -n $i | rev | cut -d "/" -f1 | rev )
    docker pull $i
    docker tag $i $DESTINATION_REGISTRY_NAMESPACE/$image
    docker push $DESTINATION_REGISTRY_NAMESPACE/$image
done