AWS CDK - How to add multiple http methods to the same resource

Question

How can I have a standard endpoint of /spaces but different lambda functions for different HTTP methods?

I was hoping I'd be able to use a helper function

addResource(path: string, method: HttpMethods, lambda: lambda.Function) {
  const lambdaIntegration: LambdaIntegration = new LambdaIntegration(lambda, { proxy: true });
  const resource: Resource = this.restApi.root.addResource(path);

  resource.addMethod(method, lambdaIntegration, {
    authorizationType: AuthorizationType.IAM,
  });

  return resource;
}

And just call it for each resource I want to add

// POST - spaces
gateway.addResource('spaces', HttpMethods.POST, new Function(this, 'droppixel-space-post', {
    runtime: Runtime.NODEJS_12_X,
    code: Code.fromAsset(`${__dirname}/../lambda-fns/space-api/src`),
    handler: 'create.handler',
    environment: {
        TABLE: table.table.tableArn
    }
}))

// GET - spaces
gateway.addResource('spaces', HttpMethods.GET, new Function(this, 'droppixel-space-get', {
    runtime: Runtime.NODEJS_12_X,
    code: Code.fromAsset(`${__dirname}/../lambda-fns/space-api/src`),
    handler: 'list.handler',
    environment: {
        TABLE: table.table.tableArn
    }
}))

This works well with just one resource, but adding additional will fail with

There is already a Construct with name 'spaces' in RootResource [Default]

Is there a proper pattern for how to do this nicely?

Answer 1

Your method addResource is performing this.restApi.root.addResource(path) each time you invoke the method, in your case twice, hence the error about the duplicate.

If you need to keep existing shape of the custom addResource method, you can verify whether the resource is already defined on given path via https://docs.aws.amazon.com/cdk/api/latest/docs/@aws-cdk_aws-apigateway.Resource.html#getwbrresourcepathpart . If the resource exists you will skip duplicate addition of the resouce.