Use event.pathParameters.proxy instead of event.path

[hfhchan-plb]

Prerequisites

• I have written a descriptive issue title
• I have searched existing issues to ensure the bug has not already been reported

Fastify version

3.3.1

Plugin version

No response

Node.js version

18.x

Operating system

macOS

Operating system version (i.e. 20.04, 11.3, 10)

13.5

Description

While migrating from serverless-express, I noticed that paths are being processed differently by aws-lambda-fastify. It seems that serverless-express will use event.pathParameters.proxy instead of event.path, which means if on API Gateway I have it configured 'v2/{proxy+}' and I am accessing /v2/token, it will call the express router with the path /token instead of /v2/token.

I wonder if an additional flag can be added to replicate that behaviour?

Steps to Reproduce

I'm using this with NestJS:

      const expressApp = express();
      const adapter = new ExpressAdapter(expressApp);
      await initApp(adapter, appModule);
      const server = configure({
        app: expressApp,
        binarySettings: { contentTypes: ['application/pdf', 'application/x-gzip'] },
      });
      return server;

vs

      const adapter = new FastifyAdapter();
      await initApp(adapter, appModule);
      const server = awsLambdaFastify(adapter.getInstance() as FastifyInstance, {
        binaryMimeTypes: ['application/pdf', 'application/x-gzip'],
        decorateRequest: true,
      });
      return server;

and NestJS with express gives me req.route.path = '/token' while NestJS with fastify gives me req.routerPath = '/v2/token'.

Expected Behavior

Matching serverless-express or providing a flag to toggle that behaviour.

[hfhchan-plb]

Looks like that behaviour was added to serverless-express in 2021:
CodeGenieApp/serverless-express#86

[adrai]

How does the configured route look in your code? similar to https://github.com/fastify/aws-lambda-fastify/blob/master/test/basic.test.js#L23 ?
Can you create a PR with a failing test?

[adrai]

I did not test it, but it might be it would work by changing this line like this:

- let url = event.path || event.rawPath || '/' // seen rawPath for HTTP-API
+ let url = (event.pathParameters && event.pathParameters.proxy && `/${event.pathParameters.proxy}`) || event.path || event.rawPath || '/' // seen rawPath for HTTP-API

Can you test this?

[hfhchan-plb]

Yes that works, but I'm not sure how it should interact with retainStage.

[adrai]

Can you please provide a new test case based on your example?
How does your event look like?

[adrai]

Just released v3.4.1 that should work.

pass the pathParameterUsedAsPath option like this:

      const adapter = new FastifyAdapter();
      await initApp(adapter, appModule);
      const server = awsLambdaFastify(adapter.getInstance() as FastifyInstance, {
        binaryMimeTypes: ['application/pdf', 'application/x-gzip'],
        decorateRequest: true,
        pathParameterUsedAsPath: 'proxy'
      });
      return server;

In case this does not work for you, please provide a new test case.

[hfhchan-plb]

How does your event look like?

{
  "body": null,
  "headers": {},
  "httpMethod": "GET",
  "isBase64Encoded": false,
  "multiValueHeaders": {},
  "multiValueQueryStringParameters": null,
  "path": "/data/token",
  "pathParameters": { "proxy": "data/token" },
  "queryStringParameters": null,
  "requestContext": {
    "path": "/v2/data/token",
    "protocol": "HTTP/1.1",
    "resourcePath": "/prod/v2/{proxy*}",
    "stage": "prod"
  },
  "resource": "/v2/{proxy+}",
  "stageVariables": null
}

(This is using serverless-offline with API gateway path: 'v2/{proxy+}' specified, with sensitive fields stripped)

[adrai]

Oh, yes I forgot the types...
v3.4.2 should address this