(apigateway): Imported RestAPIs do not have access to its methods due to casting

[peterwoodworth]

Describe the bug

Imported RestAPIs are returned by CDK as IRestAPI. However in the source code, the imports extend RestAPIBase which features additional helpful methods, such as the metric methods. The IRestAPI interface does not come with methods such as the metric methods, which prevents methods from being called without casting the imported RestAPI as a RestAPIBase.

Expected Behavior

I expect to be able to use methods that are okay to use on an imported RestAPI.

Current Behavior

I cannot use some methods that I should be able to

Reproduction Steps

You can successfully call the method using the following code. Note that removing the typecasting causes this to fail

export class TestingStack extends cdk.Stack {
  public restApi: apigw.RestApiBase;
  constructor(scope: Construct, id: string, props?: cdk.StackProps) {
    super(scope, id, props);

    this.restApi = apigw.RestApi.fromRestApiId(this,"MyGatewayApi","restApiId") as apigw.RestApiBase;
    
    const api = new cw.Alarm(this, `api-error-alarm`, {
      alarmName: 'api-error-alarm',
      threshold: 5,
      evaluationPeriods: 1,
      metric: this.restApi.metricServerError()
    });
  }
}

Possible Solution

Probably put these methods on IRestAPI interface, but I didn't dive too deep into this so that could have other side effects.

Additional Information/Context

No response

CDK CLI Version

latest

Framework Version

No response

Node.js Version

16

OS

mac

Language

Typescript

Language Version

No response

Other information

Sourced from this discussion