def outline_gcp_project(project_index, project, zone, key_file_path):
    """Return a summary of a GCP project for logging purpose.

    Arguments:
        project_index (int): Project index.
        project (Resource): GCP Resource object of the project.
        zone (str): Name of the zone for the project.
        key_file_path (str): Path of the service account key file
            for a project.

    Returns:
        str: Return a string that can be used in log messages.

    """
    zone_log = '' if zone is None else 'zone: {}; '.format(zone)
    return ('project #{}: {} ({}) ({}); {}key_file_path: {}'
            .format(project_index, project.get('projectId'),
                    project.get('name'), project.get('lifecycleState'),
                    zone_log, key_file_path))