Add support for AppSync events.

[DwayneCoussement]

Add support for AppSync.

Motivation:

AppSync is a common AWS Service, so it might be nice to support OOB support.

Modifications:

This is a purely additive change to support AWS AppSync. An AppSync.Request and AppSync.Response was added.

Result:

You'll be able to listen to AppSync requests as follows:

let myHandler = { (context: Lambda.Context, event: AppSync.Request, callback: (Result<AppSync.Response<MyCodableModel>, Error>) -> Void) in

}

let myHandler = { (context: Lambda.Context, event: AppSync.Request, callback: (Result<JSONStringResponse, Error>) -> Void) in

}

[swift-server-bot]

Can one of the admins verify this patch?

[swift-server-bot]

Can one of the admins verify this patch?

[swift-server-bot]

Can one of the admins verify this patch?

[swift-server-bot]

Can one of the admins verify this patch?

[fabianfett]

Thanks @DwayneCoussement for the pr and thanks @lgaches for the first round of reviews!

@DwayneCoussement would you mind running swiftformat . once on your code (please make sure you are in the project directory before you run it)? This should make the soundness check succeed.

Further I left a small number of comments. Do you know of any documentation of the AppSync Lambda Event types that we can link in the top of the file? Comparable to what we have done here:

swift-aws-lambda-runtime/Sources/AWSLambdaEvents/DynamoDB.swift

Lines 17 to 20 in bfdeb75

	// https://docs.aws.amazon.com/lambda/latest/dg/with-ddb.html
	public struct DynamoDB {
	public struct Event: Decodable {
	public let records: [EventRecord]

[DwayneCoussement]

Thanks @DwayneCoussement for the pr and thanks @lgaches for the first round of reviews!

@DwayneCoussement would you mind running swiftformat . once on your code (please make sure you are in the project directory before you run it)? This should make the soundness check succeed.

Further I left a small number of comments. Do you know of any documentation of the AppSync Lambda Event types that we can link in the top of the file? Comparable to what we have done here:

swift-aws-lambda-runtime/Sources/AWSLambdaEvents/DynamoDB.swift

Lines 17 to 20 in bfdeb75

	// https://docs.aws.amazon.com/lambda/latest/dg/with-ddb.html
	public struct DynamoDB {
	public struct Event: Decodable {
	public let records: [EventRecord]

@lgaches also thanks for the suggestions and first code review. @fabianfett, thank you for the second review, I've applied the requested changes as well! :)

[fabianfett]

@swift-server-bot test this please

[tomerd]

@swift-server-bot test this please

[tomerd]

@swift-server-bot test this please

[tomerd]

The documentation in https://docs.aws.amazon.com/appsync/latest/devguide/resolver-context-reference.html#aws-appsync-resolver-context-reference-identity says:

Identity

The identity section contains information about the caller. The shape of this section depends on the authorization type of your AWS AppSync API.

For more information about this section and how it can be used, see Security.

API_KEY authorization
The identity field isn’t populated.

AWS_IAM authorization
The identity has the following shape:

{
    "accountId" : "string",
    "cognitoIdentityPoolId" : "string",
    "cognitoIdentityId" : "string",
    "sourceIp" : ["string"],
    "username" : "string", // IAM user principal
    "userArn" : "string",
    "cognitoIdentityAuthType" : "string", // authenticated/unauthenticated based on the identity type
    "cognitoIdentityAuthProvider" : "string" // the auth provider that was used to obtain the credentials
}

AMAZON_COGNITO_USER_POOLS authorization
The identity has the following shape:

{
    "sub" : "uuid",
    "issuer" : "string",
    "username" : "string"
    "claims" : { ... },
    "sourceIp" : ["x.x.x.x"],
    "defaultAuthStrategy" : "string"
}

Should we model this differently?

[DwayneCoussement]

This is a good point! I've updated the model slightly here to take this all into account. Some updates were needed for AWS_IAM authorization. Please see the latest commit

[fabianfett]

@swift-server-bot test this please

[tomerd]

@swift-server-bot test this please

[tomerd]

lgtm @fabianfett ?

[fabianfett]

LGTM