Docker image name regular expression

docker-image-name-regexp.sh

#!/bin/bash

cat <<EOT | grep -nP '^(?:([a-zA-Z0-9.-]+(?:\.[a-zA-Z0-9-]+)+)(?::(\d+))?\/)?((?:[^/:\r\n]*\/)*?)([^/:\r\n]+)(?::([^/:\r\n]+))?$'
hostname.example.com:80/some/path-to/image_name-1.0:with_tag-1.0.0
hostname.example.com/some/path-to/image_name-1.0:with_tag-1.0.0
some/path-to/image_name-1.0:with_tag-1.0.0
image_name-1.0:with_tag-1.0.0
hostname.example.com:80/some/path-to/image_name-1.0
hostname.example.com/some/path-to/image_name-1.0
some/path-to/image_name-1.0
image_name-1.0
EOT