[@types/aws-lambda] Support API Gateway websocket integration

[loikg]

• I tried using the @types/aws-lambda package and had problems.
• I tried using the latest stable version of tsc. https://www.npmjs.com/package/typescript
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• Mention the authors (see Definitions by: in index.d.ts) so they can respond.
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WebSocket APIs in Amazon API Gateway have been announce recently (see here) and the documentation can be found here

I am new to Typescript and AWS thus why i am not making a pull request directly but i am willing to prepare one. From my understanding the documentation reference for the field in the API Gateway event can be found here.

For testing purpose i simply added connectionId and routeKey field to APIGatewayEventRequestContext interface like so:

export interface APIGatewayEventRequestContext {
    ...
    identity: {
        ...
    };
    connectionId ?: string;
    routeKey ?: string;
    ...
}

If i was to make a pull request is it the correct modification i should be doing and thus just add the remaining new fields to APIGatewayEventRequestContext as optional fields ?

[simonbuchan]

Thanks for the offer, and welcome! Your suggested code seems fine, not having seen the event myself, and shouldn't be any trouble to get in, but be aware that DefinitelyTyped PRs are expected to do a couple more things, The "Contributing" section in the DefinitelyTyped readme goes into the steps to take, but fortunately you have a lot of examples to look at to get an idea of what's involved in updating aws-lambda in particular. Essentially you will just need to add some level of testing (I don't really expect exhaustive testing for aws-lambda, the existing tests are largely just read and write the fields)

Pedantically (which is our job 😉) that last link is to the mapping template, in VTL, not the received event. This lets you send somewhat arbitrary content to your API gateway backend, using the custom integration. The event type in @types/aws-lambda is for the proxy integration, which should look very similar though.

For some reason AWS is terrible at documenting their lambda events, at best you get an example like this, but I couldn't see an example specifically for WebSocket. Ideally you would capture (in cloudwatch or whatever) the actual event(s) received to get an idea of what you could receive, it sounds like that's effectively what you did?

[loikg]

Hi, thanks for the answer ! I will look into the required steps and tests for the PR and submit one when i have time.

Yes i do find the AWS documentation terrible regarding events. Thank for pointing out that the last link is not the event documentation.

Yes currently i use a combination of the websocket developer guide and and output of the event in cloudwatch to see what's in the event.