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Manuals / Python / Ch 10

D · HTTPIntermediate40 min read

10. Errors, logging & CLI glue

Python · 52 pages source format

try/except specific exceptions. logging module over print. argparse for CLI tools. ruff for lint/format.

What you'll learn

  • try/except/else/finally
  • logging levels
  • argparse basics
  • ruff format

Specific exceptions

Catch FileNotFoundError, httpx.HTTPStatusError — not bare except. Re-raise when you cannot handle.

try:
    resp = httpx.get(url, timeout=5.0)
    resp.raise_for_status()
except httpx.TimeoutException:
    logging.error("Timeout fetching %s", url)
except httpx.HTTPStatusError as e:
    logging.error("HTTP %s for %s", e.response.status_code, url)

Do this now

Wrap httpx call: catch timeout and HTTP errors with clear messages.

Clear?

logging over print

logging.info/warning/error with format. Control level via LOG_LEVEL env or flag.

Do this now

Replace prints in glue script with logging.

Clear?

argparse CLI

argparse.ArgumentParser for --url, --verbose. Entry point if __name__ == "__main__".

Do this now

Add CLI to health check: python -m src.health_check --file urls.txt -v

Clear?

Checklist