53 lines
2.1 KiB
Markdown
53 lines
2.1 KiB
Markdown
---
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id: fccd4277-a253-4f7f-8065-7a9cffd64354
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type: fix
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title: "Fix: Prevent duplicate POSTs when audit update fails after successful delivery in outbound-event-handler"
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tags: [esb-monorepo, tac, outbound-event-handler, error-handling, fix, cloud-functions, idempotency, duplicate-prevention]
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importance: 0.7
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confidence: 0.8
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created: "2026-02-25T17:47:36.634745+00:00"
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updated: "2026-02-26T18:58:20.763237+00:00"
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relations:
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- target: ca8d0390-7ff9-4ca7-b033-3656d653c2be
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type: FOLLOWS
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direction: outgoing
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strength: 0.7
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edge_id: e5812091-5454-4f1b-ae62-23f2bec97f33
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---
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# Fix: Duplicate POST Prevention on Audit Failure
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## Project
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esb-monorepo — TAC `outbound-event-handler` (GCF)
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## Problem
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Bitbucket Rovo Dev flagged a code design issue: if `update_processed_events()` fails at Step 5 (after all POSTs to `outbound-object-router` succeeded), the function returned HTTP 500. Cloud Scheduler treats any 5xx as a failure and retries, causing duplicate POSTs to the downstream router for events that were already delivered.
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## Root Cause
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The final audit DB update call (`update_processed_events`) was not wrapped in error handling. A transient DB failure at that step caused the function to surface a 500, even though all delivery work was complete.
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## Fix
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Wrapped the final `update_processed_events` call in a `try/except` block:
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- Logs the audit error at ERROR level
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- Still returns **200** because all deliveries succeeded — the audit failure is non-fatal
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- Cloud Scheduler will NOT retry, preventing duplicate POSTs
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## Important Distinction
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The partial-progress flush in the POST failure path (~line 165) is intentionally **NOT** wrapped. In that case we DO want 500 returned so Cloud Scheduler retries the failed POST delivery.
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```python
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# Step 5 — audit update: non-fatal, deliveries already complete
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try:
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update_processed_events(processed_ids)
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except Exception as e:
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logger.error("Audit update failed after successful delivery: %s", e)
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return make_response("OK", 200)
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```
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## Test Added
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`test_audit_update_failure_after_all_posts_succeed_returns_200`
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## Commit
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`320b871` on `dev-object-handler` branch
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