Fix endpoint, permissions and throttling for aws-py-apigateway-serverless.

[holocronweaver]

This PR fixes some issues with the API Gateway REST and HTTP endpoints in the aws-py-apigateway-serverless example. It also updates the README to including testing the endpoints.

Changes

• Proxy API Gateway REST endpoints require the {proxy+} on the address. Without this a missing token error occurs.
• Add a trailing forward slash ('/') to the API Gateway HTTP endpoint so it can be directly invoked. Without this slash a 404 error occurs.
• Add same lambda invoke permissions for HTTP endpoint that REST endpoint has.
• API Gateway HTTP endpoints throttle all requests if no throttling config is provided, so set a reasonably low (but non-zero) throttling config.
• Update README with how to test the endpoints.

Testing

I used httpie (pip3 install httpie) for testing the V2 endpoint, but curl works just as well in this case.

Setup:

$ cd pulumi-examples/aws-py-apigateway-lambda-serverless
... do your regular AWS Pulumi config, like setting AWS region and profile ...
$ pulumi up

Before changes:

$ http $(pulumi stack output apigatewayv2-http-endpoint)
HTTP/1.1 429 Too Many Requests
Connection: keep-alive
Content-Length: 31
Content-Type: application/json
Date: Wed, 14 Sep 2022 17:35:27 GMT
apigw-requestid: YdeS4jKHPHcEPsw=

{
    "message": "Too Many Requests"
}

After adding the throttling config:

$ pulumi up
$ http $(pulumi stack output apigatewayv2-http-endpoint)
HTTP/1.1 500 Internal Server Error
Apigw-Requestid: YdeWEgzPPHcEPdQ=
Connection: keep-alive
Content-Length: 35
Content-Type: application/json
Date: Wed, 14 Sep 2022 17:35:47 GMT

{
    "message": "Internal Server Error"
}

API Gateway access logs revealed it was indeed a IAM permission issue when invoking the lambda.

After adding the invoke permission to the lambda:

$ pulumi up
$ http $(pulumi stack output apigatewayv2-http-endpoint)
HTTP/1.1 200 OK
Apigw-Requestid: YdeYKidLPHcEPEw=
Connection: keep-alive
Content-Length: 26
Content-Type: text/plain; charset=utf-8
Date: Wed, 14 Sep 2022 17:36:01 GMT

"Cheers from AWS Lambda!!"

Similar before and after for the REST endpoint:

$ http $(pulumi stack output apigateway-rest-endpoint)
HTTP/1.1 403 Forbidden
...

{
    "message": "Missing Authentication Token"
}

... change the REST endpoint export to include /{proxy+} suffix ...
$ pulumi up
$ http $(pulumi stack output apigateway-rest-endpoint)
HTTP/1.1 200 OK
...

"Cheers from AWS Lambda!!"

[github-actions]

PR is now waiting for a maintainer to run the acceptance tests.

Note for the maintainer: To run the acceptance tests, please comment /run-example-tests on the PR

[dixler]

LGTM. Thanks!