Wired in a simple callback to handle SNS notifications from S3

S3 will send a message when a file lands - which will trigger processing of DVLA responses.

app/__init__.py

@@ -95,6 +95,7 @@ def register_blueprint(application):
     from app.notifications.receive_notifications import receive_notifications_blueprint
     from app.notifications.notifications_ses_callback import ses_callback_blueprint
     from app.notifications.notifications_sms_callback import sms_callback_blueprint
+    from app.notifications.notifications_letter_callback import letter_callback_blueprint
     from app.authentication.auth import requires_admin_auth, requires_auth, requires_no_auth
     from app.letters.send_letter_jobs import letter_job
 
@@ -155,6 +156,9 @@ def register_blueprint(application):
     letter_job.before_request(requires_admin_auth)
     application.register_blueprint(letter_job)
 
+    letter_callback_blueprint.before_request(requires_no_auth)
+    application.register_blueprint(letter_callback_blueprint)
+
 
 def register_v2_blueprints(application):
     from app.v2.notifications.post_notifications import v2_notification_blueprint as post_notifications

app/notifications/notifications_letter_callback.py

@@ -0,0 +1,39 @@
+from datetime import datetime
+
+from flask import (
+    Blueprint,
+    jsonify,
+    request,
+    current_app,
+    json
+)
+
+from app import statsd_client
+from app.clients.email.aws_ses import get_aws_responses
+from app.dao import (
+    notifications_dao
+)
+
+from app.notifications.process_client_response import validate_callback_data
+
+letter_callback_blueprint = Blueprint('notifications_letter_callback', __name__)
+
+from app.errors import (
+    register_errors,
+    InvalidRequest
+)
+
+register_errors(letter_callback_blueprint)
+
+
+@letter_callback_blueprint.route('/notifications/letter/dvla', methods=['POST'])
+def process_letter_response():
+    try:
+        dvla_request = json.loads(request.data)
+        current_app.logger.info(dvla_request)
+        return jsonify(
+            result="success", message="DVLA callback succeeded"
+        ), 200
+    except ValueError:
+        error = "DVLA callback failed: invalid json"
+        raise InvalidRequest(error, status_code=400)

tests/app/notifications/rest/test_callbacks.py

@@ -13,6 +13,16 @@ from app.models import NotificationStatistics
 from tests.app.conftest import sample_notification as create_sample_notification
 
 
+def test_dvla_callback_should_not_need_auth(client):
+    data = json.dumps({"somekey": "somevalue"})
+    response = client.post(
+        path='/notifications/letter/dvla',
+        data=data,
+        headers=[('Content-Type', 'application/json')])
+
+    assert response.status_code == 200
+
+
 def test_firetext_callback_should_not_need_auth(client, mocker):
     mocker.patch('app.statsd_client.incr')
     response = client.post(