Upload file(s) to S3 Bucket on Deploy

In my serverless handler.js file I need to know the name of the S3 bucket and key that was created and synched in my npm script using the aws cli. I want this config info for the S3 bucket and key in only one location (my-config.js, my-config.json, package.json or other).

What ways would you recommend so that the config is defined once and can be used in my build/deploy scripts as well as the Lambda function code?