The gcloud command has a wrapper function to run a docker command to push and pull. For example, if you want to push the image gcr.io/kubernetes-cookbook/my-nginx, use the gcloud command:
$ gcloud docker -- push gcr.io/kubernetes-cookbook/my-nginx
It is sufficient to push the image from your machine, however, it is not ideal if you integrate with Kubernetes. This is because it is not easy to wrap the gcloud command on the Kubernetes node.
Fortunately, there is a solution that creates a GCP service account and grants a permission (role) to it.