[apigateway] ability to add methods and resources to an imported RestApi

[tjsteinhaus]

I currently have a Stack for both my Lambda's and API Gateway methods, but I'm now hitting my resource limit. By creating a new Stack I currently don't see the ability to access/use an existing api gateway, but instead it creates a new api instead.

Is there a way to access these gateways from other stacks?

[rix0rrr]

You should be able to use the export/import mechanism

const restApiImportProps = restApi.export();

// ...

const api = apigw.RestApi.import(stack2, 'APIGW', restApiImportProps);

[tjsteinhaus]

So I just tried this approach this morning and this is the error that I receive.

UnhandledPromiseRejectionWarning: TypeError: Cannot read property 'addResource' of undefined

I was looking through the source code and I see that they do not exist in the ImportedRestApi class, only in the RestAPI class. Is this by design? If so, I'm assuming this means that it's a readonly state so I can't continue to add routes from another stack? Or is this portion incomplete?

Just seems to be an inconvenience, not really with the CDK but more with CloudFormation's limit of 200 resources.

[rix0rrr]

Thanks for trying, I'll classify this as a bug for now until we can get around to fixing it.

[eladb]

@tjsteinhaus indeed it is currently impossible to modify the model of a RestApi resource that was defined in another stack. This is why import returns an IRestApi, which doesn't have any of the addXxx methods. This is indeed a limitation of the current CDK implementation, which we should consider to revisit.

I am wondering, though, how did the typescript compiler let you use the api object returned from import in such a way that resulted in the above error? Can you share your code?

[tjsteinhaus]

@eladb I'm not using Typescript but just good ol' plain Javascript.

But I can show you an abbreviated version of what we're doing.

Stack 2

var api = new apigw.RestApi(this, 'myacctapi');
this.apiexport = api.export();

Stack 6

class MyStack6 extends cdk.Stack {
	constructor(parent, id, props) {
		super(parent, id, props);
		var api = apigw.RestApi.import(this, 'myacctapi', props.apiexports );
...

MyApp CDK Main Class

...
// API-gw and the backend lambda's
		var dev2 = new MyStack2(this, 'myaccount-p2', {
			...
		});

...
var dev6 = new MyStack6(this, 'myaccount-p6', {
			apiexports: dev2.apiexport,
			stack2: dev2,
			auth: dev2.auth
		});

Stack 6 is where we are trying to extend the api gateway instead of creating a new one.

[danielfariati]

This feature would be really useful for me as well.

I'm basically trying to use the same API Gateway for multiple microservices.
So, it would be nice if I could make a CDK stack register itself on an existing API Gateway, instead of manually configuring it every time a new microservice is added.