py-cookiecutter-templates/docker-compose/hooks/pre_gen_project.py

import sys

service_slug = "{{ cookiecutter.__service_slug }}"
component_list_slug = "{{ cookiecutter.__component_list_slug }}"
for v in (service_slug, component_list_slug):
    if not v:
        print(f"Please answer all prompts with a non-empty string. Aborting and exiting 3 ...")
        sys.exit(3)