Enabling service

gcloud services enable containerregistry.googleapis.com  

Initializing ProjectID

export PROJECT_ID=<PROJECT ID> # Replace this with your GCP Project
ID  

Getting Busybox

docker pull busybox  
docker images  

Creating code (using vim Dockerfile)

cat <<EOF >>Dockerfile  
from busybox:latest  
CMD ["date"]  
EOF

Building

docker build . -t mybusybox  

Tagging following GCP Container Registry convention

docker tag mybusybox gcr.io/$PROJECT_ID/mybusybox:latest  

Running

docker run gcr.io/$PROJECT_ID/mybusybox:latest  

Wiring credentials of GCP Container Registry with Docker

gcloud auth configure-docker  

Pushing image to container registry

docker push gcr.io/$PROJECT_ID/mybusybox:latest