Add new DAG pull_image with PythonOperator pull_docker_image
Add a new dag which allows to pull an image with a certain tag from a repository. The dag can be triggered using the airflow REST API via command line. Example:
airflow trigger_dag 'pull_image' --conf '{"repository": "harbor.pht.medic.uni-tuebingen.de/library/busybox", "tag": "latest"}'