Adding support for APIGatewayV2 (Web Sockets)

[TimGustafson]

Issue #, if available:
N/A

Description of changes:
Added support for APIGatewayV2 events.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[bmoffatt]

Can provide a link to the relevant AWS documentation and sample data?

[TimGustafson]

The basic AWS documentation about WebSocket APIs is available at:

https://docs.aws.amazon.com/apigateway/latest/developerguide/apigateway-websocket-api.html

Documentation specific to the Lambda Proxy integration can be found at:

https://docs.aws.amazon.com/apigateway/latest/developerguide/api-gateway-create-api-as-simple-proxy-for-lambda.html

Is that what you're looking for?

[bmoffatt]

Going to use aws/aws-lambda-go#159 as a sample data reference

[bmoffatt]

Having 'V2' in the name may be confusing for future readers. Putting Websocket in the type name will be clearer

[mukhtar]

Thanks for the change.

The runtime currently fails to be deserialize the request into APIGatewayV2ProxyRequestEvent. I believe the two inner classes need to be declared static. See APIGatewayProxyRequestEvent.

[mukhtar]

Can you also add the remaining fields to APIGatewayV2ProxyRequestEvent? See aws/aws-lambda-go#159.

[TimGustafson]

I've added the static declaration for the inner classes, and also added the missing properties.

[mukhtar]

I'm facing an issue with the authorizer field which is an object in the sample from the aws-lambda-go repo. It seems it can be either a string or an object according to the aws-lambda-go pr. Any reason you selected String?

[TimGustafson]

I have changed the authorizer field to be a Map<String,Object> so that it will take just about anything that comes in a map format. I've tested this against an APIGatewayV2 deployment that have an authorizer configured, and one that does not. It appears to work in both cases.

In investigating this, I realized that we also don't have classes for APIGatewayV2Authorizer(Request|Response) objects and started creating these to make authorizers easier to author in Java, but ran into a problem where Java serialization lower-cases the first letter of each property by default, but the policyDocument returned by the custom authorizer needs to have "Effect", "Action" and "Resources" all begin with a capital letter. I'm going to spend a bit more time to see if I can get that to work, as I believe that will provide a superior experience for users, and then I'll also supply some demo code (including a CloudFormation template) to demonstrate how to use these, as doing so right now is non-trivial, and required me to spend quite a bit of time doing trial-and-error until I got it just right.

If I do create those APIGatewayV2Authorizer(Request|Response) classes, should I include them in this fork, or should we close this (since technically they're not required for the APIGatewayV2Proxy(Request|Response)Event objects) and open a new fork for the authorizer classes?

[mukhtar]

Thanks! I think it would be great to get the APIGatewayV2Proxy(Request|Response) merged in so if we remove APIGatewayV2Authorizer(Request|Response) we're good to go. I tested this too and LGTM.

[TimGustafson]

I have removed the custom authorizer classes. (Sorry, I didn't realize I had added them to the master branch!)

[mukhtar]

LGTM. Added serialVersionUID to the serializable classes and updated the multivalue header and params value type to List<String> to be consistent with APIGatewayProxyRequestEvent.

[adamnfish]

Is there any reason the new APIGatewayV2ProxyResponseEvent class lacks withX methods? The non-v2 version does include withX methods and I think that's the common pattern for the AWS SDKs?

Here's an example of an existing with method on the original APIGatewayProxyResponseEvent class:
https://github.com/aws/aws-lambda-java-libs/blob/master/aws-lambda-java-events/src/main/java/com/amazonaws/services/lambda/runtime/events/APIGatewayProxyResponseEvent.java#L44

Thanks very much this contribution, this will be a great help. Any idea when it will be available in a public release?