from astropy import time
import numpy as np
import string


def gen_dag_run_id(digits=6):
    """
    Generate a unique run_id for a dag.
    """
    now = time.Time.now()
    dag_run_id = now.strftime("%Y%m%d-%H%M%S-")

    n = len(string.ascii_lowercase)
    for i in range(digits):
        dag_run_id += string.ascii_lowercase[np.random.randint(low=0, high=n)]
    return dag_run_id