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Level 4 / Project 14 - Configurable Batch Runner

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— This project — — Flashcards — Browser

Estimated time: 75 minutes

Focus

  • batch jobs driven by config files

Why this project exists

This project gives you level-appropriate practice in a realistic operations context. Goal: run the baseline, alter behavior, break one assumption, recover safely, and explain the fix.

Run (copy/paste)

Use <repo-root> as the folder containing this repository's README.md.

cd <repo-root>/projects/level-4/14-configurable-batch-runner
python project.py --config data/batch_config.json --output data/batch_report.json
pytest -q

Expected terminal output

{
  "total_jobs": 4,
  "succeeded": 4,
  "failed": 0
}
6 passed

Expected artifacts

  • data/batch_report.json — per-job results with status
  • Passing tests
  • Updated notes.md

Checkpoint: Baseline code runs and all tests pass. Commit your work before continuing.

Alter it (required) — Extension

  1. Add a new action: search_pattern that counts regex matches in a file.
  2. Add a --dry-run flag that validates the config without executing jobs.
  3. Re-run script and tests — add a test for the new action.

Break it (required) — Core

  1. Reference a non-existent file in the config and verify the error is logged per-job.
  2. Add a job with an unknown action name and confirm it is skipped.
  3. Create a config with zero jobs and verify the runner handles it.

Fix it (required) — Core

  1. Add config schema validation (each job must have name, action, input).
  2. Add timing to each job result (duration_ms).
  3. Re-run until all tests pass.

Checkpoint: All modifications done, tests still pass. Good time to review your changes.

Explain it (teach-back)

  1. Why does the batch runner use an ACTIONS registry instead of if/elif chains?
  2. What is the advantage of running jobs sequentially with individual error handling vs. stopping at first failure?
  3. Why does run_batch resolve input paths relative to the config file's directory?
  4. How would you extend this to support job dependencies (job B runs only if job A succeeds)?

Mastery check

You can move on when you can: - run baseline without docs, - explain one core function line-by-line, - break and recover in one session, - keep tests passing after your change.

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