You must have a Kubernetes cluster and make sure that the Kubernetes node has accessibility to the Docker Hub (https://hub.docker.com) in order to download Docker images.
If you are running minikube, use minikube ssh to log on to the minikube VM first, then run the docker pull command.
You can simulate downloading a Docker image by using the docker pull command as follows:
//this step only if you are using minikube
$ minikube ssh
_ _
_ _ ( ) ( )
___ ___ (_) ___ (_)| |/') _ _ | |_ __
/' _ ` _ `| |/' _ `| || , < ( ) ( )| '_` /'__`
| ( ) ( ) || || ( ) || || |` | (_) || |_) )( ___/
(_) (_) (_)(_)(_) (_)(_)(_) (_)`\___/'(_,__/'`\____)
//run docker pull to download CentOS docker image
$ docker pull centos
Using default tag: latest
latest: Pulling from library/centos
d9aaf4d82f24: Pull complete
Digest: sha256:4565fe2dd7f4770e825d4bd9c761a81b26e49cc9e3c9631c58cfc3188be9505a
Status: Downloaded newer image for centos:latest