HTTP Proxy using APIGateway with CDK

Last week at work I had to integrate an ALB with APIGateway as a proxy. While its pretty straight forward with Console, Unfortunately, it was not using CDK. This is due to my lack of complete knowledge, and their docs. Both suck 😁.

Let’s look at the code on how to integrate APIGateway with an URL

import * as cdk from "aws-cdk-lib";
import { Construct } from "constructs";
import { HttpIntegration, RestApi } from "aws-cdk-lib/aws-apigateway";
// import * as sqs from 'aws-cdk-lib/aws-sqs';

export class ApiGwHttpProxyStack extends cdk.Stack {
  constructor(scope: Construct, id: string, props?: cdk.StackProps) {
    super(scope, id, props);

    // 👉 👉  ALB URL
    const albUrl = "http://example.com";

    // 👉 👉 first create a REST API Gateway
    const restAPI = new RestApi(this, "httpProxyAPIGateway", {
      restApiName: "httpProxyAPIGateway",
    });

    // 👉 👉 https://docs.aws.amazon.com/apigateway/latest/developerguide/setup-http-integrations.html
    const proxyIntegration = new HttpIntegration(`${albUrl}/{proxy}`, {
      httpMethod: "ANY",
      options: {
        requestParameters: {
          "integration.request.path.proxy": "method.request.path.proxy",
        },
      },
      proxy: true,
    });

    // 👉 👉 https://docs.aws.amazon.com/apigateway/latest/developerguide/setup-http-integrations.html
    const proxyMethodOptions = {
      requestParameters: {
        "method.request.path.proxy": true,
      },
    };

    // 👉 👉 top level empty route
    // for some reason API Gateway doesn't attach single `/` path so attaching it here
    restAPI.root.addMethod(
      "ANY",
      new HttpIntegration(albUrl, {
        httpMethod: "ANY",
      }),
    );

    // this could be an empty resource too
    const resource = restAPI.root.addResource(`some-resource`);

    // proxy
    resource
      .addResource("{proxy+}")
      .addMethod("ANY", proxyIntegration, proxyMethodOptions);
  }
}

The above code deploys APIGateway and Integrates Proxy. Let’s deploy it with following command

cdk deploy

CDK outputs APIGateway URL as follows