CDK, or Amazon Web Services Cloud Development Kit, is a CLI tool and a set of libraries that generate CloudFormation. Thus it is one way that you can define your AWS infrastructure in code.
An example of what this means:
Request a DynamoDB table, an AppSync API, three lambdas, and a fargate service from AWS. Deploy these three lambdas with access to the DynamoDB table and attach the lambdas as resolvers to the AppSync API. Include an environment variable specifying this as
production in all the lambdas and allow one of them to read the Stripe secret key using AWS Secrets Manager. Create an EC2 VPC, an ECS cluster and ask for 6 instances of the
application image in it. Diff this against production to see what's going to change and then deploy the changes.