Benzene

Hosting on AWS Lambda (API Gateway + SQS + SNS)

Host one set of Benzene handlers on AWS Lambda across three event sources — API Gateway, SQS, and SNS — and publish events back out over SNS. One function, one pipeline, the handlers unchanged.

Prerequisites

Build the host and entry point

The domain wiring (router + registry) is shared with every other cloud; only the host is AWS-specific:

# main.py
from benzene.aws import AwsLambdaApp, SnsMessageSender, to_lambda_handler
from orders_domain import OrderService, build_orders

wiring = build_orders(OrderService(), SnsMessageSender("arn:aws:sns:...:orders"))
app = AwsLambdaApp(http_router=wiring.router, registry=wiring.registry)
handler = to_lambda_handler(app)     # point your Lambda at main.handler

The single handler dispatches by event shape:

Test every source in memory (dogfooded)

from benzene.aws.testing import AwsLambdaTestHost, SqsEventBuilder
from benzene.testing import FakeMessageSender

sender = FakeMessageSender()
host = AwsLambdaTestHost(build_app(sender=sender))

# API Gateway ingress -> handler -> SNS egress
resp = host.send_http("POST", "/orders", body={"sku": "ABC"})
assert resp.status_code == 201 and sender.last_topic == "orders.created"

# SQS + SNS ingress
assert host.send_sqs("orders.created", {"id": "1", "sku": "A"}) == {"batchItemFailures": []}
host.send_sns("orders.created", {"id": "2", "sku": "B"})

# SQS partial-batch failure: only the bad record is reported
event = (SqsEventBuilder()
         .with_message("orders.created", {"id": "3", "sku": "C"}, message_id="m1")
         .with_message("orders.unknown", {}, message_id="m2")
         .build())
assert host.send_sqs_event(event) == {"batchItemFailures": [{"itemIdentifier": "m2"}]}

Deploy (sketch)

Package examples/ with the benzene-* dependencies, set the handler to main.handler and BENZENE_SNS_TOPIC_ARN, then attach the triggers: an API Gateway proxy integration, an SQS event-source mapping, and an SNS subscription. All three flow into the same handler.

See also