feat(event-handler): add resolution logic to base router

[svozza]

Summary

This PR implements the final resolution logic for the BaseRouter class. The resolve method is no longer abstract and has a concrete implementation where it looks up the route registry using the path and tries to retirve a resolver for the route. If not route is found, we throw a NotFoundErroe. If any exceptions are thrown from the handler, these are caught and handled by the already existing handleError method.

Changes

• Update BaseRouter to have. oncrete implementation of resolve method
• Added new conversion functions to produce the APIGatewayProxyResult type that lambda expects
• Updated the unit tests now that the resolve function is implemented in the base class
• Added tests to ensure this context is preserved when using decorators.

Issue number: closes #4142

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[dreamorosi]

I know we added this in a previous PR, but after testing the BaseRouter in a Lambda function behind API Gateway REST I think I found a bug in the proxyEventToWebRequest function.

Specifically, the headers parsing (below), is problematic as it concatenates values if the same header is present in both headers and multiValueHeaders - which seems to be always the case in my tests:

for (const [name, value] of Object.entries(event.headers ?? {})) {
  if (value != null) headers.append(name, value);
}

for (const [name, values] of Object.entries(event.multiValueHeaders ?? {})) {
  for (const value of values ?? []) {
    headers.append(name, value);
  }
}

For example this request payload (shortened for brevity):

{
  "resource": "/",
  "path": "/",
  "httpMethod": "GET",
  "headers": {
    "Host": "abcd1234.execute-api.eu-west-1.amazonaws.com",
    "X-Forwarded-Proto": "https"
  },
  "multiValueHeaders": {
    "Host": ["abcd1234.execute-api.eu-west-1.amazonaws.com"],
    "X-Forwarded-Proto": ["https"]
  },
  "queryStringParameters": null,
  "multiValueQueryStringParameters": null,
  "pathParameters": null,
  "stageVariables": null,
  "requestContext": { ... },
    "domainName": "abcd1234.execute-api.eu-west-1.amazonaws.com",
    "deploymentId": "abcd123",
    "apiId": "abcd1234"
  },
  "body": null,
  "isBase64Encoded": false
}

results in this:

console.log(headers.get('Host'));
// abcd1234.execute-api.eu-west-1.amazonaws.com, abcd1234.execute-api.eu-west-1.amazonaws.com 
console.log(headers.get('X-Forwarded-Proto'));
// https, https

making the URL parsing at L40 fail together with the request.

Additionally, like in this case, the proxyEventToWebRequest function is called and run twice both when first parsing the request and then again in the except block when trying to run the handleError - is there any way that we can run it only once?

Another thing I noticed is that when using API Gateway REST, the requestContext.path field includes the stage as path prefix, for example in a stage prod making a request to stuff would result in "path":"/prod/stuff".

Do we expect customers to have to set it in as prefix at the router level, or in their route handlers? Should we instead just use the top level path and resource fields which in this case would be respectively /stuff and /?

[svozza]

I know we added this in a previous PR, but after testing the BaseRouter in a Lambda function behind API Gateway REST I think I found a bug in the proxyEventToWebRequest function.

Specifically, the headers parsing (below), is problematic as it concatenates values if the same header is present in both headers and multiValueHeaders - which seems to be always the case in my tests:

I've added logic to check whether the header already includes a value before we append it.

Additionally, like in this case, the proxyEventToWebRequest function is called and run twice both when first parsing the request and then again in the except block when trying to run the handleError - is there any way that we can run it only once?

I've moved the creation of the Request object out of the try/catch handler so we now only do it once.

Another thing I noticed is that when using API Gateway REST, the requestContext.path field includes the stage as path prefix, for example in a stage prod making a request to stuff would result in "path":"/prod/stuff".

Do we expect customers to have to set it in as prefix at the router level, or in their route handlers? Should we instead just use the top level path and resource fields which in this case would be respectively /stuff and /?

Agreed, I've changed it to use the top level fields instead.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
8.1% Duplication on New Code

See analysis details on SonarQube Cloud