Feature request: Add Event handler for AWS Lambda Function URLs

[gwlester]

Use case

With the general availability of AWS Lambda Function URLs to implement microservices AWS Lambda Powertools for Python should support handling this event type.

This should support the routes being specified in a separate file just like for other event handlers.

Solution/User Experience

from aws_lambda_powertools import Logger, Tracer
from aws_lambda_powertools.logging import correlation_paths
from aws_lambda_powertools.event_handler import FunctionUrl

tracer = Tracer()
logger = Logger()
app = FunctionUrl()

@app.get("/hello")
@tracer.capture_method
def get_hello_universe():
    return {"message": "hello universe"}

# You can continue to use other utilities just as before
@logger.inject_lambda_context(correlation_id_path=correlation_paths.FUNCTION_URL)
@tracer.capture_lambda_handler
def lambda_handler(event, context):
    return app.resolve(event, context)

Alternative solutions

No response

Acknowledgment

• This feature request meets Lambda Powertools Tenets
• Should this be considered in other Lambda Powertools languages? i.e. Java, TypeScript

[gwlester]

It would be nice if when specifying the route an optional "authorizer function" could be passed. Such a function would have the same signature as a handler and whose result could be a boolean indicating if access is allowed or not. If no "authorizer function" then all access would be allowed for that route.

[heitorlessa]

Thank you @gwlester for showing interest in having support for Lambda Function URL. We'll look into it after we return from our pause.

We built support during beta, so it should be technically a days job to revisit and consider maintenance aspects.

As for authorisers, we'd prefer to create a middleware support for event handler (in-flight, after the pause) so that we don't recommend non-function URL customers to disregard API GW/ALB/AppSync Authorizer capabilities.

Thank you!

[michaelbrewer]

@gwlester this already works via the http api handler

[michaelbrewer]

This code works fine

from aws_lambda_powertools import Logger, Tracer
from aws_lambda_powertools.logging import correlation_paths
from aws_lambda_powertools.event_handler import APIGatewayHttpResolver

tracer = Tracer()
logger = Logger()
app = APIGatewayHttpResolver()

@app.get("/hello")
@tracer.capture_method
def get_hello_universe():
    return {"message": "hello universe"}

# You can continue to use other utilities just as before
@logger.inject_lambda_context(correlation_id_path=correlation_paths.API_GATEWAY_HTTP)
@tracer.capture_lambda_handler
def lambda_handler(event, context):
    return app.resolve(event, context)

Also the sample projects works ok too:

from aws_lambda_powertools import Logger, Metrics, Tracer
from aws_lambda_powertools.event_handler.api_gateway import APIGatewayHttpResolver
from aws_lambda_powertools.logging import correlation_paths
from aws_lambda_powertools.metrics import MetricUnit

logger = Logger(service="APP")
tracer = Tracer(service="APP")
metrics = Metrics(namespace="MyApp", service="APP")
app = APIGatewayHttpResolver()


@app.get("/hello/<name>")
@tracer.capture_method
def hello_name(name):
    tracer.put_annotation(key="User", value=name)
    logger.info(f"Request from {name} received")
    metrics.add_metric(name="SuccessfulGreetings", unit=MetricUnit.Count, value=1)
    return {"message": f"hello {name}!"}


@app.get("/hello")
@tracer.capture_method
def hello():
    tracer.put_annotation(key="User", value="unknown")
    logger.info("Request from unknown received")
    metrics.add_metric(name="SuccessfulGreetings", unit=MetricUnit.Count, value=1)
    return {"message": "hello unknown!"}


@tracer.capture_lambda_handler
@logger.inject_lambda_context(
    correlation_id_path=correlation_paths.API_GATEWAY_HTTP, log_event=True
)
@metrics.log_metrics(capture_cold_start_metric=True)
def lambda_handler(event, context):
    try:
        return app.resolve(event, context)
    except Exception as e:
        logger.exception(e)
        raise

{
    "level": "INFO",
    "location": "decorate:352",
    "message": {
        "version": "2.0",
        "routeKey": "$default",
        "rawPath": "/hello/foo",
        "rawQueryString": "",
        "headers": {
            "sec-fetch-mode": "navigate",
            "sec-fetch-site": "none",
            "accept-language": "en-US,en;q=0.9",
            "x-forwarded-proto": "https",
            "x-forwarded-port": "443",
            "x-forwarded-for": "24.25.211.231",
            "sec-fetch-user": "?1",
            "accept": "text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.9",
            "sec-gpc": "1",
            "x-amzn-trace-id": "Root=1-6260fcf5-4cf3d34a732581c86e1a7e0e",
            "host": "bg6wooanpk5l6pte7d73k2flmy0pmkms.lambda-url.us-east-2.on.aws",
            "upgrade-insecure-requests": "1",
            "cache-control": "max-age=0",
            "accept-encoding": "gzip, deflate, br",
            "sec-fetch-dest": "document",
            "user-agent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/100.0.4896.127 Safari/537.36"
        },
        "requestContext": {
            "accountId": "anonymous",
            "apiId": "bg6wooanpk5l6pte7d73k2flmy0pmkms",
            "domainName": "bg6wooanpk5l6pte7d73k2flmy0pmkms.lambda-url.us-east-2.on.aws",
            "domainPrefix": "bg6wooanpk5l6pte7d73k2flmy0pmkms",
            "http": {
                "method": "GET",
                "path": "/hello/foo",
                "protocol": "HTTP/1.1",
                "sourceIp": "24.25.211.231",
                "userAgent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/100.0.4896.127 Safari/537.36"
            },
            "requestId": "ed9f2d37-4585-479b-98c0-3dea09aaecaf",
            "routeKey": "$default",
            "stage": "$default",
            "time": "21/Apr/2022:06:43:01 +0000",
            "timeEpoch": 1650523381869
        },
        "isBase64Encoded": false
    },
    "timestamp": "2022-04-21 06:43:01,874+0000",
    "service": "APP",
    "sampling_rate": "0.1",
    "cold_start": false,
    "function_name": "sam-app-HelloWorldFunction-jNNQamivEruW",
    "function_memory_size": "256",
    "function_arn": "arn:aws:lambda:us-east-2:254688924456:function:sam-app-HelloWorldFunction-jNNQamivEruW",
    "function_request_id": "ed9f2d37-4585-479b-98c0-3dea09aaecaf",
    "correlation_id": "ed9f2d37-4585-479b-98c0-3dea09aaecaf",
    "xray_trace_id": "1-6260fcf5-4cf3d34a732581c86e1a7e0e"
}

[gwlester]

@michaelbrewer -- after looking at the code last night it looked like it would "just work". It would still be nice to have an explicit class for it.

I know ya'll did some work on this already -- would you mind/like if I took a crack and submitted a Pull Request with it (assuming that I have time before August)?

[michaelbrewer]

Go for it. But to save you time and frustration, I would suggest waiting for an official green light from the maintainers, otherwise your PR will most likely be closed.

Also for Function Url we should probably have some disclaimers and warnings around security.

[gwlester]

Ok, I will just wait for a status change on this or to hear back from ya'll.

[heitorlessa]

Hey @gwlester we'll be looking in implementing official support for Lambda Function URL as soon as our pause ends.

[rubenfonseca]

Hi @gwlester! We're looking to start implementing this feature for release at the end of the next week. We would love if you had the change to contribute the necessary changes yourself. Otherwise, we will also be happy to take a look and ask you for a review. What would be the best for you?