def METHOD_NAME(cluster_name):
    """
    Build the payload needed to create an authenticated datasource in Grafana for `cluster_name`.
    Args:
        cluster_name: name of the cluster
    Returns:
        dict object: req payload to be consumed by Grafana
    """
    # Get the prometheus address for cluster_name
    datasource_url = get_cluster_prometheus_address(cluster_name)
    # Get the credentials of this prometheus instance
    prometheus_creds = get_cluster_prometheus_creds(cluster_name)
    datasource_details = {
        "name": cluster_name,
        "type": "prometheus",
        "access": "proxy",
        "url": f"https://{datasource_url}",
        "basicAuth": True,
        "basicAuthUser": prometheus_creds["username"],
        "secureJsonData": {"basicAuthPassword": prometheus_creds["password"]},
    }
    return datasource_details