Error resolving path in Api Gateway event handler

Suppose one has two routes to delete resources like the following:

Use Case 1:

Route in handler

@app.delete("/accounts/<account_id>")
def delete_account(account_id: str) -> None:

Request

{
        "path": "/accounts/123",
        "httpMethod": "DELETE",
        "requestContext": {"requestId": "c6af9ac6-7b61-11e6-9a41-93e8deadbeef"},  # correlation ID
}

Use Case 2:

@app.delete("/accounts/<account_id>/source_networks")
def delete_source_networks(account_id: str) -> Account:

Request

{
        "path": "/accounts/123/source_networks"
        "httpMethod": "DELETE",
        "requestContext": {"requestId": "c6af9ac6-7b61-11e6-9a41-93e8deadbeef"},  # correlation ID
}

Expected Behavior

Expected behavior is that account_id equals 123 in both use cases

Current Behavior

For use case 1 resolver calls the right function and sets account_id = 123
For use case 2, resolver calls the function of use case 1 and sets accound_id = 123/source_networks

Possible Solution

Not sure if this is actually the expected behavior of proxy integration with its greedy regexp or a bug in Lambda Power Tools

Environment

Power Tools version 1.17.1

delete_source_networks_event = {'body': '{"networks": ["172.217.0.0/16", "8.8.8.8"]}', 'httpMethod': 'DELETE', 'path': **'/accounts/123/source_networks'**, ...}
{"level":"INFO","location":"delete:209","message":"Account deleted","timestamp":"2021-07-11 15:12:42,205-0300","service":"admin_api","cold_start":false,"function_name":"FUNCTION_NAME","function_memory_size":1024,"function_arn":"INVOKED_FUNCTION_ARN","function_request_id":"AWS_REQUEST_ID","correlation_id":"c6af9ac6-7b61-11e6-9a41-93e8deadbeef",**"account_id":"123/source_networks"**,"tax_id":"123","service_id":3}

@marcioemiranda

Hey @marcioemiranda , thanks for raising it! Could you share how you're configuring API Gateway?

At a first glance this looks like API GW route matching, so I've created this additional test for use case 2 and it works as expected --- I'm creating an API Gateway with the same path to be on the safe side and report back with a repro repo.

def test_nested_dynamic_routes():
    # GIVEN
    app = ApiGatewayResolver()
    event = deepcopy(LOAD_GW_EVENT)

    @app.get("/accounts/<account_id>/source_networks")
    def get_lambda(account_id: str):
        assert account_id == "123"
        return {"message": "okay"}

    event["resource"] = "/accounts/{account_id}/source_networks"
    event["path"] = "/accounts/123/source_networks"
    # WHEN calling the event handler
    result = app(event, {})

    # THEN
    assert result["statusCode"] == 200

Yup, confirmed, it's a bug --- I can replicate that locally with SAM CLI start-api too: https://github.com/heitorlessa/pt-issue-520

Test to reproduce the issue - If I define both functions with similar path in the tests it fails exactly as described

def test_nested_dynamic_routes():
    # GIVEN
    app = ApiGatewayResolver()
    event = deepcopy(LOAD_GW_EVENT)
    event["resource"] = "/accounts/{account_id}/source_networks"
    event["path"] = "/accounts/12345/source_networks"

    # first rule will be a match, hence not calling the right function
    # re.compile('^/accounts/(?P<account_id>.+)$')
    @app.get("/accounts/<account_id>")
    def get_lambda(account_id: str):
        assert account_id == "12345"
        return {"message": f"{account_id}"}

    # re.compile('^/accounts/(?P<account_id>.+)/source_networks$')
    @app.get("/accounts/<account_id>/source_networks")
    def get_lambda(account_id: str):
        assert account_id == "12345"
        return {"message": f"{account_id}"}

    # WHEN calling the event handler
    result = app(event, {})

    # THEN
    assert result["statusCode"] == 200

@michaelbrewer

@michaelbrewer could you look into it as discussed?

@marcioemiranda as a workaround until we fix it, you could change the order of the function definition for the longest/nested being the first one.

For example:

@app.get("/accounts/<account_id>/source_networks")
def account_nested(account_id: str):
    print(f"[ACCOUNT NESTED] Account ID received: --> {account_id}")
    return {"account": f"{account_id}"}

@app.get("/accounts/<account_id>")
def account(account_id: str):
    print(f"[ACCOUNT SINGLE] Account ID received: --> {account_id}")
    return {"account": f"{account_id}"}

@heitorlessa

@heitorlessa thanks for the workaround.
API gateway was provisioned by CDK => construct LambdaRestApi in '@aws-cdk/aws-apigateway'
BTW, on a different subject, I wonder when #506 will be released.

We're working on some MyPy fixes and as soon as I complete #517 we'll release it OR the documentation for the new Feature Toggles utility ##494

ETA next Friday if all goes well

fix(api-gateway): route pattern regex aws-powertools#520

@marcioemiranda

We've got a fix and will ping back once released this week @marcioemiranda ;)

If you're curious: #533

@marcioemiranda

Opa @marcioemiranda - This is now available in 1.18.0

More details in the release notes: https://github.com/awslabs/aws-lambda-powertools-python/releases/tag/v1.18.0

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Error resolving path in Api Gateway event handler #520

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Error resolving path in Api Gateway event handler #520

Description

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Current Behavior

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heitorlessa commented on Jul 16, 2021

heitorlessa commented on Jul 16, 2021

heitorlessa commented on Jul 16, 2021

marcioemiranda commented on Jul 16, 2021

heitorlessa commented on Jul 16, 2021

heitorlessa commented on Jul 18, 2021

heitorlessa commented on Jul 20, 2021

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