Deploying multiple Serverless Framework apis to the same AWS API Gateway

By default, each Serverless project you deploy will create a new API Gateway. In most cases this works fine, but for larger projects you may need to split your apis across multiple smaller Serverless projects, each with their own serverless.yml that can be deployed independently.

The Serverless docs describe how to do this here. In each additional Serverless project where you want to add additional apis to an existing API Gateway, you need to specify 2 additional properties in your Serverless.yml, apiGateway and restApiRootResourceId:

provider:
  name: aws
  apiGateway:
    restApiId: xxxxxxxxxx # REST API resource ID. Default is generated by the framework
    restApiRootResourceId: xxxxxxxxxx # Root resource, represent as / path

apiGateway – this is the 11 character id for your API Gateway that you want to add resources to. You can get this from the console and it’s the prefix in your api gw url, e.g. https://aaaaaaaaaaa.execute-api.us-west-1.amazonaws.com/dev

The id for the root resource is where in your api path structure you want to add your new resource to, either the id of the root / or one of the existing paths beneath the root.

This id value I don’t think is visible in the console, but you can get it a list of all the resources in your API Gateway including the ids of each of the existing resources, with:

aws apigateway get-resources --rest-api-id aaaaaaaaaaa --region us-west-2

It will give a response that looks like:

{
    "items": [
        {
            "id": "bbbbbb",
            "parentId": "aaaaaaaaaa",
            "pathPart": "example1",
            "path": "/example1",
            "resourceMethods": {
                "GET": {}
            }
        },
        {
            "id": "aaaaaaaaaa",
            "path": "/"
        }
    ]
}

In this example I have a root / with id = aaaaaaaaa and a resource bbbbbb for /example1.

In this case if I pass aaaaaaaaaa as the value for restApiRootResourceId then my new resource will be added to /, or passing bbbbbb it will be added as a resource under /example1

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