feat(P04): nova-idp-jwks Lambda — JWKS endpoint (REQ-338, D-230, backend-engineer)

---ci--- project: acdl phase: 4 milestone: v1.28 status: execute persona: backend-engineer ---
2026-08-19 23:08:32 +00:00
parent cd3418a75e
commit 0662ed26a3
2 changed files with 186 additions and 0 deletions
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+"""Nova IdP JWKS endpoint Lambda (REQ-338, D-230).
+
+Serves the KMS public key as a JWK in a standard JWKS response. The
+endpoint is a Lambda function URL with ``AuthType: NONE`` (JWKS is
+public-key only — configured in CloudFormation, not in code).
+
+Response:
+  * ``Content-Type: application/json``
+  * ``Cache-Control: public, max-age=3600`` (1h — clients cache the JWKS)
+  * ``Access-Control-Allow-Origin: *`` (JWKS is public)
+  * ``body: {"keys": [<jwk>]}``
+
+The JWK is built via :func:`core.kms_signing.get_jwk` from the KMS
+public key (DER SPKI → ``cryptography`` → JWK).
+
+Dual-use (REQ-329): ``__main__`` CLI block for local testing
+(``--print-jwks``).
+"""
+
+from __future__ import annotations
+
+import json
+import os
+import sys
+
+OIDC_KMS_KEY_ID = os.environ.get("NOVA_OIDC_KMS_KEY_ID", "alias/nova-oidc-signing")
+
+
+def lambda_handler(event, context):
+    """AWS Lambda handler — serve the JWKS response (REQ-338)."""
+    try:
+        from core.kms_signing import get_jwk
+        jwk = get_jwk(key_id=OIDC_KMS_KEY_ID)
+        return {
+            "statusCode": 200,
+            "headers": {
+                "Content-Type": "application/json",
+                "Cache-Control": "public, max-age=3600",
+                "Access-Control-Allow-Origin": "*",
+            },
+            "body": json.dumps({"keys": [jwk]}),
+        }
+    except Exception as e:
+        return {
+            "statusCode": 500,
+            "headers": {"Content-Type": "application/json"},
+            "body": json.dumps({"error": str(e)}),
+        }
+
+
+def cli_main(argv=None):
+    """CLI entry point (REQ-329 dual-use). ``--print-jwks`` → stdout."""
+    raw = argv if argv is not None else sys.argv[1:]
+    if "--print-jwks" in raw:
+        resp = lambda_handler({}, None)
+        sys.stdout.write(resp["body"] + "\n")
+        return resp.get("statusCode", 200) - 200
+    print("Usage: python3 -m core.lambda.nova_idp_jwks --print-jwks", file=sys.stderr)
+    return 2
+
+
+if __name__ == "__main__":  # pragma: no cover - CLI entry
+    sys.exit(cli_main())