Best Practices for Managing AWS CDK - TypeScript Code

Introduction

The AWS Cloud Development Kit (AWS CDK) is an open-source software development framework that allows developers to define cloud infrastructure using familiar programming languages. AWS CDK simplifies the process of provisioning AWS resources by enabling the use of high-level constructs and reusable components.

What is the need for AWS CDK?

The need for programming language-based Infrastructure as Code (IaC) emerged from the limitations of traditional declarative IaC tools like AWS CloudFormation. While effective, these tools required extensive configuration files written in JSON or YAML, which could become unwieldy and difficult to manage, especially in large-scale applications. The complexity and verbosity of these configurations often led to errors and reduced productivity.

AWS CDK was created to address these challenges by allowing developers to use general-purpose programming languages such as TypeScript, Python, Java, and C#. This approach provides several key advantages:

1. Improved Abstraction and Reusability: By using programming constructs, developers can create higher-level abstractions and reusable components, making infrastructure definitions more modular and maintainable.
2. Enhanced Productivity: Familiar programming languages allow developers to leverage existing skills, libraries, and tools, reducing the learning curve and increasing development speed.
3. Increased Flexibility: AWS CDK enables the use of logic and loops, providing greater flexibility and expressiveness compared to traditional declarative templates.
4. Strong Typing and IDE Support: Using typed languages offers better error checking and autocompletion in Integrated Development Environments (IDEs), leading to fewer errors and faster development cycles.

Why AWS CDK Matters

AWS CDK represents a significant shift in how infrastructure is defined and managed in the cloud. By combining the power of programming languages with the robustness of AWS CloudFormation, AWS CDK provides a more developer-friendly approach to IaC. This not only enhances productivity and maintainability but also fosters best practices in infrastructure management, making it easier for teams to build, deploy, and manage cloud applications at scale.

In summary, AWS CDK is a game-changer for cloud infrastructure management, addressing the shortcomings of traditional IaC tools and providing a more efficient, flexible, and developer-friendly way to define and manage cloud resources.

Explore AWS CDK further by building a simple application and experimenting with its features. Check out the official AWS CDK documentation to get started.

Other similar technologies are Pulumi and CDKTF

Context setting for this Article

Typescript is one of widely used technology stack in AWSCDK.

It's important to organize your codebase clearly when structuring an AWS CDK project for TypeScript in GitHub, and ensure you include all necessary files while excluding sensitive or unnecessary files.

In this article, we will see how to structure AWSCDK Typescript code and it's best practices.

Directory Structure

Your project directory should look something like this:

my-cdk-project/
|-- bin/
|   |-- my-cdk-project.ts        # Entry point of the CDK app
|-- lib/
|   |-- my-cdk-project-stack.ts  # Defines a stack
|-- environments/            # Custom folder for environment-specific configurations
|       |-- dev.ts
|       |-- prod.ts
|-- node_modules/                # Node.js modules (excluded from Git)
|-- test/
|   |-- my-cdk-project.test.ts   # Unit tests
|-- .gitignore                   # Git ignore file
|-- cdk.json                     # CDK configuration
|-- package.json                 # Node.js dependencies
|-- tsconfig.json                # TypeScript configuration
|-- README.md                    # Project documentation        

Files to Push to GitHub

Source Code:

• bin/: Contains the entry point of your CDK application.
• lib/: Contains your stack definitions.
• environments/: environment configurations.
• test/: Contains your unit tests.

Configuration Files:

• cdk.json: Configuration file for CDK.
• package.json: Lists your Node.js dependencies.
• tsconfig.json: TypeScript compiler configuration.
• README.md: Documentation for your project.

Hidden Files:

• .gitignore: Specifies files and directories to ignore in Git.

Files to Exclude (Using .gitignore)

Your .gitignore file should include the following entries to exclude unnecessary files:

node_modules/
cdk.out/
.env
*.js
*.d.ts
*.js.map
.vscode/
.idea/
.DS_Store
*.log        

Best Practices

1. Environment Variables: Use environment variables to manage sensitive information like AWS credentials. Store these in a .env file and make sure to add this file to .gitignore.
2. Documentation: Keep your README.md file up-to-date with instructions on how to set up and deploy the project.
3. Branching Strategy: Use a branching strategy such as Git Flow or GitHub Flow to manage feature development and releases.
4. CI/CD Integration: Set up CI/CD pipelines using GitHub Actions or another CI/CD tool to automate testing and deployment.
5. Code Reviews: Implement a code review process to ensure code quality and consistency across the team.
6. Separate Git Repositories: Use separate repositories if you have distinct teams managing network and application components, otherwise use a monorepo.
7. Monorepo could be useful for most of the projects.
8. CDK Stack Grouping:

• Network Stack: VPC, subnets, route tables, gateways.
• Security Stack: Security groups, IAM roles/policies.
• Compute Stack: EC2 instances, auto-scaling groups, load balancers.
• Storage Stack: S3 buckets, EFS.
• Database Stack: RDS instances, database clusters.
• Security Groups: Include security groups in the stack where they are most relevant. Application-specific security groups can be included with the compute resources, while reusable security groups can be in a separate security stack.

To know more about the AWSCDK for Typescript file organisation and Best practices refer to my Github repo here.

Also check this AWS Samples repo for more implementation examples.

Reach out to me for developing IaC in AWSCDK, Pulumi or CDKTF.

Saravanan Gnanaguru