---
id: T02
parent: S05
milestone: M001
provides:
  - AwsSgClient wrapping boto3 describe_security_group_rules with async and error handling
  - AwsSgTranslator converting AWS SecurityGroupRule dicts to UniversalRule objects
  - AwsSecurityGroupAdapter implementing FirewallAdapter ABC (get_rules, validate, capabilities)
  - Constraint validation for AWS SG limits (allow-only, 60-rule limit, CIDR validation)
requires: []
affects: []
key_files: []
key_decisions: []
patterns_established: []
observability_surfaces: []
drill_down_paths: []
duration: 5min
verification_result: passed
completed_at: 2026-03-10
blocker_discovered: false
---
# T02: 05-firewall-adapter 02

**# Phase 5 Plan 02: AWS SG Adapter Summary**

## What Happened

# Phase 5 Plan 02: AWS SG Adapter Summary

**AWS Security Group adapter with boto3 client, stateless rule translator, and 6-check constraint validation against allow-only/60-rule AWS limits**

## Performance

- **Duration:** 5 min
- **Started:** 2026-03-10T15:55:38Z
- **Completed:** 2026-03-10T16:00:59Z
- **Tasks:** 2
- **Files modified:** 10

## Accomplishments
- AwsSgClient wraps boto3 describe_security_group_rules with async (asyncio.to_thread) and structured error handling (AdapterError/AdapterAuthenticationError)
- AwsSgTranslator.from_sg_rule correctly converts all AWS SG rule types: CidrIpv4, CidrIpv6, security group references, all-traffic (-1), and ICMP
- AwsSecurityGroupAdapter implements FirewallAdapter ABC with get_rules(), validate(), and capabilities()
- Validation catches 6 constraint violations: DENY action, wide-open source, rule limit exceeded, invalid protocol, invalid port range, invalid CIDR
- 235 total tests pass (38 new adapter tests), pyright and ruff clean

## Task Commits

Each task was committed atomically (TDD: RED then GREEN):

1. **Task 1: AWS SG client, translator, and dev dependency update** - `00d6d13` (feat)
2. **Task 2: AWS SG adapter with validation and integration tests** - `b9b81c7` (feat)

## Files Created/Modified
- `src/policyfoundry/adapters/aws_sg/__init__.py` - Package exports AwsSecurityGroupAdapter
- `src/policyfoundry/adapters/aws_sg/client.py` - Thin boto3 EC2 wrapper with async describe_rules
- `src/policyfoundry/adapters/aws_sg/translator.py` - Stateless AWS SecurityGroupRule to UniversalRule translator
- `src/policyfoundry/adapters/aws_sg/adapter.py` - AwsSecurityGroupAdapter implementing FirewallAdapter ABC with validation
- `pyproject.toml` - Updated moto[ec2,s3] and boto3-stubs[s3,ec2] dev dependencies
- `tests/test_adapters/conftest.py` - Shared moto fixtures and sample AWS SG rule dicts
- `tests/test_adapters/test_aws_sg_translator.py` - 13 translator unit tests
- `tests/test_adapters/test_aws_sg_adapter.py` - 7 integration tests with moto mock_aws
- `tests/test_adapters/test_validation.py` - 18 constraint validation tests
- `tests/test_adapters/test_registry.py` - Updated fallback test (aws_sg module now exists)

## Decisions Made
- Stateless translator pattern: AwsSgTranslator uses only static methods with no instance state, making it pure and easy to test
- ICMP type/code values (FromPort/ToPort) mapped to port_range=None since they are ICMP semantics, not TCP/UDP ports
- Used frozenset for auth error codes, valid protocols, and wide-open CIDRs for O(1) membership checks
- Validation collects all errors rather than short-circuiting, so users see every issue in a single call

## Deviations from Plan

### Auto-fixed Issues

**1. [Rule 1 - Bug] Fixed registry fallback test for existing aws_sg module**
- **Found during:** Task 2 (full test suite verification)
- **Issue:** test_get_adapter_fallback_aws_sg expected AdapterNotFoundError because aws_sg module didn't exist in Plan 01; now that the module exists, the import succeeds but adapter requires security_group_id
- **Fix:** Updated test to pass security_group_id kwarg and assert successful AwsSecurityGroupAdapter instantiation
- **Files modified:** tests/test_adapters/test_registry.py
- **Verification:** Full test suite passes (235 tests)
- **Committed in:** b9b81c7 (Task 2 commit)

**2. [Rule 1 - Bug] Fixed adapter integration test for malformed SG ID**
- **Found during:** Task 2 (GREEN phase)
- **Issue:** test_get_rules_invalid_sg_id expected empty list, but moto raises ClientError for malformed SG IDs which our client correctly wraps in AdapterError
- **Fix:** Updated test to expect AdapterError with correct sg_id in details
- **Files modified:** tests/test_adapters/test_aws_sg_adapter.py
- **Verification:** Test passes, verifying error wrapping works correctly
- **Committed in:** b9b81c7 (Task 2 commit)

---

**Total deviations:** 2 auto-fixed (2 bugs in test expectations)
**Impact on plan:** Both fixes corrected test expectations to match actual moto behavior. No scope creep.

## Issues Encountered
None

## User Setup Required
None - no external service configuration required. All tests use moto mock_aws and run offline.

## Next Phase Readiness
- AwsSecurityGroupAdapter is fully operational with get_rules(), validate(), and capabilities()
- AdapterRegistry.get_adapter("aws_sg", security_group_id="sg-xxx") works via both entry_points and fallback import
- Phase 7 pipeline stages can call get_rules() to fetch real SG rules and validate() to check proposed changes
- Phase 9 CLI can instantiate the adapter via the registry

## Self-Check: PASSED

All 10 files verified present. Both task commits verified in git log (00d6d13, b9b81c7).

---
*Phase: 05-firewall-adapter*
*Completed: 2026-03-10*
