Error resolving path in Api Gateway event handler

[marcioemiranda]

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}

[heitorlessa]

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

[heitorlessa]

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

[heitorlessa]

@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}"}

[marcioemiranda]

@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.

[heitorlessa]

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

[heitorlessa]

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

If you're curious: #533

[heitorlessa]

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