A Template for Effortless CDK Pipeline Integration

Introduction #

For those developing with CDK and TypeScript, you’re likely familiar with the power and efficiency of Continuous Integration and Continuous Deployment (CI/CD) pipelines. However we typically encounter two problems: 1) integrating these pipelines during the initial stages of development can sometimes slow down the process more than we’d like and isn’t necessary and 2) refactoring the application to integrate a CDK pipeline can be a time-consuming and error-prone process.

That’s where the cdk-pipeline-app-template comes in. It’s a simple, yet effective, solution I’ve created to help you focus on building your application first without the constraints of a pipeline, then when you’re ready to deploy this template allows you to integrate a CDK pipeline with minimal effort and no refactoring.

Understanding the Problem #

As developers, we understand the importance of Continuous Integration and Continuous Deployment (CI/CD) in the software development lifecycle. CI/CD pipelines are a robust solution for automating the tasks of software delivery - from integrating new features to deploying updates. Yet, incorporating these pipelines early in the development process can sometimes feel like placing the cart before the horse.

In the initial stages of development, our focus is primarily on crafting the application’s logic and testing its functionality. The continuous integration of a CI/CD pipeline during this phase can create a cycle of continuous interruptions. Each code push triggers a cascade of pipeline executions, which can lead to delays, especially if we’re faced with debugging the pipeline itself in addition to the application.

On the other hand, once the logic is ready and it’s finally time for CI/CD, refactoring the application to integrate a CDK pipeline can be a time-consuming and error-prone process.

The thing is, you don’t even need CI/CD until you’re ready to ship your application!

This is where the need for a quick, flexible solution becomes apparent - a development process that allows us to build and test the application first, without any pipeline-related overhead. And once we’re confident about the application, we should be able to make only a few minor changes to integrate it into a CI/CD pipeline with as little friction as possible.

The CDK App and Pipeline Project Template is designed to provide just that - a seamless transition from non-pipeline development to pipeline-integrated deployments. It provides a CDK Pipeline-ready template that can be applied by simply uncommenting a few lines and defining the deployment stages. The upside is that you get to focus more on the application, business or testing logic, and less on pipeline configuration, debugging, and refactoring.

Overview of the Template #

Let’s first take a look at the overall structure of the project to familiarize ourselves with it.

.
├── README.md
├── bin
│   ├── app.ts              # Develop the app with no pipeline
│   └── pipeline.ts         # Pipeline to deploy the app (disabled by default)
├── cdk.json                # Update the app entry point to bin/pipeline.ts to enable pipeline
├── config.json             # App specific configuration
├── jest.config.js
├── lib
│   ├── app                 # App modules go here
│   ├── app-stack.ts        # App modules are imported and defined here
│   ├── app-stage.ts        # Pipeline app stage (disabled by default)
│   └── pipeline-stack.ts   # Pipeline stack (disabled by default)
├── package.json
├── .gitignore              # Comment or uncomment the appropriate lines to avoid committing secrets
├── test
│   └── app.test.ts
└── tsconfig.json

The bin/app.ts file is where you import your application under development without the pipeline. The bin/pipeline.ts file, initially disabled, is what you’ll engage when you’re ready to deploy your app via a CDK pipeline. Simply uncomment its code, define the application stage in lib/app-stage.ts and the deployment stages in lib/pipeline-stack.ts, and voila - you’re ready to redeploy using the pipeline structure.

Diving Deeper: The App Without the Pipeline #

In the first part of the processed, you’ll be focused on the bin/app.ts and lib/app-stack.ts files. These two files are the core of your application’s development without the pipeline. You will be deploying the resources directly to your AWS account using the CDK CLI commands.

The bin/app.ts file is the entry point of the application. Here, you’ll initialize your app and its stack, import configurations from config.json, and apply any necessary tags to your stack.

The lib/app-stack.ts file is where you’ll define your application’s AWS resources. This is essentially your workspace where you’ll build and test your app. A good practice, although not demonstrated here is to separate your resources into modules, which you can then import into your stack. This will help you keep your code clean and organized.

...
├── lib
│   ├── app                 # App modules go here
│   ├── app-stack.ts        # Import app modules and define your stack here
│   ├── app-stage.ts
│   └── pipeline-stack.ts
...

The config.json file serves as the initial declaration of your app’s and future pipeline’s configuration values. It’s used to manage aspects such as the app’s name, stage, and tags. You’ll find this particularly helpful for maintaining consistency across different parts of your application. It has two top-level fields, cdk_app for values used by the application and cdk_pipeline for values used by the CDK Pipeline once integrated.

Once you’ve developed your app, deploying it is straightforward using the AWS CDK commands. Just run cdk deploy from your terminal, and the CDK will take care of the rest, deploying your stack to your default AWS account and region. From there you can test it and continue the development cycle.

Integrating the CDK Pipeline #

When you’re ready to integrate your app into a CDK pipeline, you’ll primarily be working with bin/pipeline.ts, lib/app-stage.ts, and lib/pipeline-stack.ts.

The pipeline.ts file, located in the bin directory, is the gateway to deploying your app via a pipeline. It’s initially disabled to allow for pipeline-free development. To enable it, you simply uncomment the code in the file.

lib/app-stage.ts and lib/pipeline-stack.ts are also part of the pipeline mechanism. They are initially disabled like pipeline.ts and need to be uncommented when you’re ready to engage the pipeline.

The app-stage.ts file encapsulates the app and its stack into a stage, which can then be deployed using the pipeline, while pipeline-stack.ts is where the pipeline and its stages are declared.

Switching from a non-pipeline to a pipeline deployment involves a simple modification in the cdk.json file. You’ll change the “app” value from "npx ts-node --prefer-ts-exts bin/app.ts" (which points to the non-pipeline app) to "npx ts-node --prefer-ts-exts bin/pipeline.ts" (which points to the pipeline-enabled app). This is important because it tells the CDK CLI which app to deploy.

// change this:
{
  "app": "npx ts-node --prefer-ts-exts bin/pipeline.ts",
  ...
}

// to this:
{
  "app": "npx ts-node --prefer-ts-exts bin/app.ts",
  ...
}

Lastly you will need to update package.json:

{
    "name": "app", // Change the name of the app
    "version": "0.1.0",
    "bin": {
    "app": "bin/app.js" // change to bin/pipeline.js
    }
}

And that’s it! With a few tweaks, you’ve transitioned your app into a CDK pipeline, ready for streamlined deployments.

Conclusion #

To conclude, the CDK app and pipeline project template offers a streamlined approach to building AWS CDK applications. It presents a clear pathway for developing an app without the complexity of a pipeline, and then, when ready, effortlessly transitioning into a pipeline-integrated deployment.

This template aims to eliminate the hurdles that often come with premature pipeline integration, giving you the flexibility and efficiency you need during the initial development and prototyping stages.

If you’re planning your next AWS CDK project, I encourage you to try this template. Navigate its structure, use it as a base for your app, and experience the benefits of a simplified, yet effective, development-to-deployment process. If you find it useful, please give it a star on GitHub and feel free to fork it or contribute your own improvements.

Additional Resources #

• CDK App and Pipeline Project Template GitHub Repository: Familiarize yourself with the repository and access the code here.

• AWS CDK Documentation: For a deep dive into AWS CDK, its constructs, and various use-cases, you can refer to the official AWS CDK documentation.

• AWS CDK Pipelines: For a focused look at AWS CDK Pipelines and how they can be utilized for continuous integration and continuous delivery, check out this developer guide.

Feel free to dive into these resources, and happy coding!