Evaluate AWS CDK Stack output to another Stack in different account - amazon-web-services

Question

I am creating two Stack using AWS CDK. I use the first Stack to create an S3 bucket and upload lambda Zip file to the bucket using BucketDeployment construct, like this.
//FirstStack
const deployments = new BucketDeployment(this, 'LambdaDeployments', {
destinationBucket: bucket,
destinationKeyPrefix: '',
sources: [
Source.asset(path)
],
retainOnDelete: true,
extract: false,
accessControl: BucketAccessControl.PUBLIC_READ,
});
I use the second Stack just to generate CloudFormation template to my clients. In the second Stack, I want to create a Lambda function with parameters S3 bucket name and key name of the Lambda zip I uploaded in the 1st stack.
//SecondStack
const lambdaS3Bucket = "??"; //TODO
const lambdaS3Key = "??"; //TODO
const bucket = Bucket.fromBucketName(this, "Bucket", lambdaS3Bucket);
const lambda = new Function(this, "LambdaFunction", {
handler: 'index.handler',
runtime: Runtime.NODEJS_16_X,
code: Code.fromBucket(
bucket,
lambdaS3Key
),
});
How do I refer the parameters automatically from 2nd Lambda?
In addition to that, the lambdaS3Bucket need to have AWS::Region parameters so that my clients can deploy it in any region (I just need to run the first Stack in the region they require).
How do I do that?

Answer 1

I had a similar usecase to this one.
The very simple answer is to hardcode the values. The bucketName is obvious.
The lambdaS3Key You can look up in the synthesized template of the first stack.
More complex answer is to use pipelines for this. I've did this and in the build step of the pipeline I extracted all lambdaS3Keys and exported them as environment variable, so in the second stack I could reuse these in the code, like:
code: Code.fromBucket(
bucket,
process.env.MY_LAMBDA_KEY
),
I see You are aware of this PR, because You are using the extract flag.
Knowing that You can probably reuse this property for Lambda Key.
The problem of sharing the names between the stacks in different accounts remains nevertheless. My suggestion is to use pipelines and the exported constans there in the different steps, but also a local build script would do the job.
Do not forget to update the BucketPolicy and KeyPolicy if You use encryption, otherwise the customer account won't have the access to the file.
You could also read about the AWS Service Catalog. Probably this would be a esier way to share Your CDK products to Your customers (CDK team is going to support the out of the box lambda sharing next on)