Let's assume you have a super/sql:experimental image with a SQL database in it. You want to use it as a base image for your job because you want to execute some tests with this database binary. Let's also assume that this image is configured with /usr/bin/super-sql run as an entrypoint. When the container starts without additional options, it runs the database's process. The runner expects that the image has no entrypoint or that the entrypoint is prepared to start a shell command.