[@aws-cdk/aws-apigatewayv2-integrations] support parameter mapping in Http Integrations

[Nowax]

I would like to have a possibility to configure parameter mapping to e.g. append or remove specific parameter in forwarded request.

Use Case

Currently there is no possibility to configure it, specifically in context of HttpAlbIntegration. These are only possible props:

 const integration = new HttpAlbIntegration({
            listener: httpApiListener,
            vpcLink: httpVpcLink,
            method: HttpMethod.ANY
        })

This functionality is available in AWS console and it's missing in aws cdk. It can be very helpful to e.g. pass some authorizer context parameters down to the backend.

Proposed Solution

It would be nice to have some additional field where proper mapping can be configured e.g.:

        const integration = new HttpAlbIntegration({
            listener: httpApiListener,
            vpcLink: httpVpcLink,
            method: HttpMethod.ANY,
            mapping: {
                request: {
                    {
                        parameter: "header.requestHeaderAppend",
                        modification: APPEND,
                        value: "$context.authorizer.PrincipalId"
                    },
                                        {
                        parameter: "header.requestHeaderRemove",
                        modification: REMOVE,
                    }
                    },
                                        {
                        parameter: "header.requestHeaderOverwrite",
                        modification: OVERWRITE,
                        value: "request overwrite value"
                    }
                }
                response: {
                    {
                        parameter: "header.responseTest",
                        modification: APPEND,
                        value: "custom response value"
                    }
                }
            }
        })

Same interface can be applied to rest of Integration classes.

Other

• 👋 I may be able to implement this feature request
• ⚠️ This feature might incur a breaking change

---

This is a 🚀 Feature Request

[dan-lind]

@nija-at I might be able to implement this. Wanted to know if someone would be available to discuss design before I get started?

[nija-at]

@Nowax, @dan-lind - could you provide links to the documentation for this feature and how it can be set up via CloudFormation?

[dan-lind]

Sure, it's here.

https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-apigatewayv2-integration.html#cfn-apigatewayv2-integration-requestparameters

Which refers to this page:

https://docs.aws.amazon.com/apigateway/latest/developerguide/http-api-parameter-mapping.html

I have a proposal that is a bit different to what Novax proposed above. Can share its later tonight.

[nija-at]

Thanks @dan-lind.

Sounds good. I would suggest that you start by opening a PR containing just the changes to the README of the aws-apigatewayv2-integrations module to describe what the user experience looks like.

Once we're happy there, you could then move to implementation.

To keep the changes manageable, I recommend focusing on the experience of HTTP APIs without an integration subtype.

[dan-lind]

@nija-at Was wondering if README changes shouldn't be in @aws-cdk/aws-apigatewayv2 rather than aws-apigatewayv2-integrations? Looks like all lower level stuff like this is kept in that main module.

[nija-at]

Perhaps. Where it goes would depend on your design.

[Nowax]

@dan-lind any idea when the Pull Request could be merged? It seems like the work is done here and only thing is missing is the merge itself.

[dan-lind]

Don't know, it's waiting for a review from someone on the CDK team

[github-actions]

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