Using Python Logging and the Halo Library to Create Friendly CLI Progress Indicators

Automation development teams often need to create test tools that communicate progress to users through standard output, such as showing "begin download", "downloading", and "download complete" messages for an HTTP download utility.

Below is a typical implementation using Python's logging module to emit debug, info, and error messages that indicate the download stages.

# -*- coding: utf-8 -*-
import time
import logging

logger = logging.getLogger()
logger.setLevel(logging.DEBUG)

fmt = logging.Formatter("[%(asctime)s] [%(levelname)s] %(message)s")

stream_handler = logging.StreamHandler()
stream_handler.setFormatter(fmt)
logger.addHandler(stream_handler)

"""
    Simulate downloading a file from the given URL
    using time.sleep as a placeholder for the actual download process
"""

def download(url):
    time.sleep(3)
    return True

def run():
    url = "http://xxx"
    logger.debug("begin download url %s" % url)
    logger.debug("downloading, plz wait...")
    if download(url):
        logger.info("download succeed")
    else:
        logger.error("download failed")

run()

The execution prints timestamped log entries that show the start, progress, and result of the simulated download.

To make the progress indication more user‑friendly, the halo library (inspired by Node.js's ora) can be used to display a spinner with success or failure messages.

# -*- coding: utf-8 -*-
import time
import logging
from halo import Halo

logger = logging.getLogger()
logger.setLevel(logging.DEBUG)

fmt = logging.Formatter("[%(asctime)s] [%(levelname)s] %(message)s")
stream_handler = logging.StreamHandler()
stream_handler.setFormatter(fmt)
logger.addHandler(stream_handler)

"""
    Simulate downloading a file from the given URL
    using time.sleep as a placeholder for the actual download process
"""

def download(url):
    time.sleep(3)
    return True

def run():
    url = "http://xxx"
    logger.debug("begin download url %s" % url)
    spinner = Halo("downloading, plz wait...", spinner="line")
    spinner.start()
    if download(url):
        spinner.succeed("download succeed")
        logger.info("download succeed")
    else:
        spinner.fail("download failed")
        logger.error("download failed")

run()

The spinner provides a dynamic, visually appealing indication while the download is simulated, and it reports success or failure with colored symbols.

Halo is inspired by the Node.js ora package; its source code is available at https://github.com/ManrajGrover/halo , and it can produce even more striking effects as shown in the accompanying GIFs.