Creating a simple Node.js/Express web application to use for our pipeline.
To build a CI/CD pipeline, we first need an application. For this project, we will create a minimal but functional web application using Node.js and the Express framework. This choice is ideal because it's lightweight, has a straightforward dependency management system (npm), and a simple testing framework (like Jest or Mocha), making it perfect for demonstrating CI/CD concepts without unnecessary complexity. The application will have a few basic API endpoints. For example, a root endpoint that returns a 'Hello World' message and a '/health' endpoint that returns a status of 'OK'. We will also write a few simple unit tests to verify the functionality of these endpoints. The code will be structured with a `package.json` file to manage dependencies and define scripts for starting the server and running tests. We will also include a `Dockerfile`. This file will contain the instructions to package our Node.js application into a standardized, portable container image. Having a containerized application simplifies the deployment process, as the same container image that was tested in the CI pipeline can be deployed to any environment, ensuring consistency from development to production. The entire application, including the source code, tests, and Dockerfile, will be checked into a Git repository on a platform like GitHub or GitLab.