MIL-007 Lecture step 9: resilience against network failures
Metadata
| Key |
Value |
| ID |
MIL-007 |
| CrossReference |
BC-001 |
| Language |
en |
| Domain |
it |
Version History
| Date |
Status |
Author |
Reviewer |
Change |
Commit |
| 2026-10-28 |
Accepted |
Jens Tirsvad Nielsen |
AI as stand-in for S02 |
Initial version |
50e8331 |
Purpose
Decide whether the bot completes a full run when the site fails half of its requests, which completes lecture step 9.
Deliverable
A retry(func, retries=7, description=None) wrapper, login(), book_class() and get_my_bookings() made resilient with it, unit tests with a failing fake, and the screenshot for lecture step 9.
Go / No-Go Criteria
| # |
Criterion (objectively checkable) |
Go |
No-Go |
| 1 |
Unit tests show that retry returns on success, repeats on failure and raises after the last attempt |
0 failures |
A test fails |
| 2 |
Booking is only counted when the page confirms it (the button changes state) |
Confirmed in tests and in a run |
A click is counted without confirmation |
| 3 |
Container runs with 50% simulated failures reach the verification result in 3 of 3 attempts |
3 of 3 |
Fewer than 3 |
| 4 |
docs/images/step-9.png exists |
The file exists |
The file is missing |
| 5 |
The code review against qc-programming-python.md is Go |
RC-* is Go |
No-Go |
Dependencies
| Depends on |
Reason |
| MIL-006 |
Needs login, booking and verification to wrap |
Traceability
| Business Case objective / KPI / user story |
Reference |
| O6, success criteria 4, 5 |
BC-001 |
| CN-003 |
SA-001 |
Ownership
| Role |
Stakeholder ID (SA) |
| Owner |
S01 |
| Approving reviewer |
S02 (AI as stand-in, autonomous mode, not independent) |
Target Date
2026-11-04 — inside the planned window 2026-10-28 to 2026-11-06 of PP-001; the Business Case sets no deadline.
Tasks
| # |
Task |
Summary |
Needs its own Use Case/User Story? |
Reference |
| 1 |
Write the retry wrapper |
Implement retry(func, retries=7, description=None) that calls the function, logs each failed attempt with the description and re-raises after the last one. Unit-test it with a fake that fails n times. |
No |
O6 |
| 2 |
Wrap the login in retry |
Move all login steps into login() and call it through retry, so a failed page load is repeated. |
No |
O6 |
| 3 |
Make booking confirm its result |
Put the booking steps in book_class() and treat the click as done only when the button reads "Booked" or "Waitlisted"; call it through retry. |
No |
O6 |
| 4 |
Make the bookings read resilient |
Put the My Bookings retrieval in get_my_bookings() and call it through retry. |
No |
O6 |
| 5 |
Run the chaos test in a container |
Clear the bookings in the admin panel, enable the network simulation at 50%, run the bot three times and keep the output. Save the screenshot step-9.png. |
No |
O6 |
