---
id: T02
parent: S03
milestone: M001
provides:
  - "ingest_from_s3: async S3 ingestion with prefix scan, gzip decompression, dedup"
requires: []
affects: []
key_files: []
key_decisions: []
patterns_established: []
observability_surfaces: []
drill_down_paths: []
duration: 6min
verification_result: passed
completed_at: 2026-03-08
blocker_discovered: false
---
# T02: 03-log-ingestion 02

**# Phase 3 Plan 2: S3 Ingestion Summary**

## What Happened

# Phase 3 Plan 2: S3 Ingestion Summary

**S3 VPC Flow Log ingestion with prefix scanning, transparent gzip decompression, and cross-object deduplication using boto3**

## Performance

- **Duration:** 6 min
- **Started:** 2026-03-09T05:41:40Z
- **Completed:** 2026-03-09T05:48:03Z
- **Tasks:** 1
- **Files modified:** 5

## Accomplishments
- S3 prefix scanning via boto3 paginator discovers all VPC Flow Log objects under a given prefix
- Transparent gzip decompression for .gz extension objects with BadGzipFile error handling
- Cross-object deduplication using shared seen-hashes set within a single ingestion run
- Graceful S3 access error handling: bucket not found and permission denied produce warnings, never crash
- aws_profile forwarded to boto3.Session for AWS credential chain support
- 12 new moto-based S3 tests, 132 total tests passing, pyright strict clean, ruff clean

## Task Commits

Each task was committed atomically:

1. **Task 1: S3 ingestion with prefix scan, gzip decompression, and moto tests**
   - `663378e` (test: RED -- failing tests for S3 ingestion)
   - `bba8ad9` (feat: GREEN -- S3 ingestion implementation)

_TDD task has RED + GREEN commits._

## Files Created/Modified
- `src/policyfoundry/ingestion/s3.py` - Async S3 ingestion with prefix scan, streaming, gzip support
- `tests/test_ingestion/test_s3.py` - 12 moto-based tests covering all S3 ingestion behaviors
- `src/policyfoundry/ingestion/__init__.py` - Added ingest_from_s3 export
- `pyproject.toml` - Added boto3, moto[s3], boto3-stubs[s3] dependencies

## Decisions Made
- Used boto3 + asyncio.to_thread instead of aioboto3 due to moto/aiobotocore version incompatibility (aiobotocore 2.25.1 fails with moto 5.1.22 on async response body handling). boto3 wrapped in asyncio.to_thread provides the same async public API with full moto test compatibility.
- S3 access errors at both bucket and object level caught separately -- bucket-level errors abort the run with warning, object-level errors skip the problematic object and continue with remaining objects.
- Source files tracked as s3://bucket/key URI format for consistent provenance with local file paths.

## Deviations from Plan

### Auto-fixed Issues

**1. [Rule 3 - Blocking] Switched from aioboto3 to boto3 + asyncio.to_thread**
- **Found during:** Task 1 (TDD RED/GREEN)
- **Issue:** moto 5.1.22 and aiobotocore 2.25.1 are incompatible -- aiobotocore's async endpoint handler tries to `await` on synchronous bytes returned by moto's response mock, causing `TypeError: object bytes can't be used in 'await' expression`
- **Fix:** Replaced aioboto3 with boto3, wrapped S3 I/O calls in `asyncio.to_thread()` to maintain async public API. Removed aioboto3 dependency, added boto3 as direct dependency, added boto3-stubs[s3] for pyright typing.
- **Files modified:** src/policyfoundry/ingestion/s3.py, pyproject.toml, uv.lock
- **Verification:** All 12 S3 tests pass with moto mock_aws, pyright strict clean
- **Committed in:** bba8ad9 (GREEN commit)

---

**Total deviations:** 1 auto-fixed (1 blocking)
**Impact on plan:** Necessary change for test infrastructure compatibility. Public API identical (async function returning IngestionResult). No scope creep.

## Issues Encountered
- moto + aiobotocore compatibility: aiobotocore 2.25.1 cannot be used with moto 5.1.22 for testing. Resolved by using boto3 (sync) with asyncio.to_thread wrapper.

## User Setup Required
None - no external service configuration required. AWS credentials resolved via boto3 default chain at runtime.

## Next Phase Readiness
- Full ingestion pipeline complete: local files (Plan 01) and S3 (Plan 02)
- Both produce identical IngestionResult format -- downstream consumers don't need to know the source
- All 4 phase requirements (INGEST-01 through INGEST-04) covered across Plans 01 and 02
- Parser, dedup, result, and both ingestion functions exported from ingestion __init__.py

## Self-Check: PASSED
