from typing import Optional


def runner_to_image(runner_name: str) -> Optional[str]:
    """
    Determine docker image based on runner name

    Args:
        runner_name: Type of test runner

    Returns:
        Docker image for runner
    """
    if runner_name == "rest-runner":
        return "cicadatesting/cicada-2-rest-runner"
    elif runner_name == "sql-runner":
        return "cicadatesting/cicada-2-sql-runner"
    elif runner_name == "kafka-runner":
        return "cicadatesting/cicada-2-kafka-runner"
    elif runner_name == "s3-runner":
        return "cicadatesting/cicada-2-s3-runner"
    elif runner_name == "grpc-runner":
        return "cicadatesting/cicada-2-grpc-runner"

    return None