Docker check if tag exists

docker-check-tag-exists.sh

export DOCKER_TAG=test

if [[ $( docker pull hello-world:$DOCKER_TAG 2>&1 | head -1 )  == *"not found"* ]] ;
then
    echo "Create image for hello world repro"
    docker pull hello-world:develop
    docker tag hello-world:develop hello-world:$DOCKER_TAG
    docker push hello-world:$DOCKER_TAG
else
    echo "Image already exists"
fi

This script checks if a specific tag exists.
If the tag was found the pull will be canceled and not downloaded!