Understand Deployment Usecase

In this guide, we’ll walk through our CI/CD pipeline stages and demonstrate how to deploy a Dockerized application to Kubernetes clusters. You’ll learn how to:

Build and test your code
Containerize with Docker
Deploy to a development cluster
Run integration tests
Promote to production after manual approval

Deployment Pipeline Overview

We’ve already completed:

Stage	Purpose
Unit Testing	Validate code logic with `npm test`
Code Coverage	Measure test coverage using `npm run coverage`
Docker Containerization	Package the app into a Docker image

Next, the pipeline will:

Push the Docker image to a container registry
Deploy to a Kubernetes development environment
Execute integration tests against the dev cluster
Await manual approval
Promote the same deployment to the production environment

Local Development Commands

Before diving into Kubernetes, run these commands locally to verify your application:

Step	Command	Description
Install	`npm install`	Install project dependencies
Test	`npm test`	Execute unit tests
Coverage	`npm run coverage`	Generate code coverage report
Build Image	`docker build -t my-app:latest .`	Create a Docker image
Run Image	`docker run -p 3000:3000 my-app:latest`	Launch the container on port 3000
Push Image	`docker push my-app:latest`	Upload the image to your registry

# Example: Build and run locally
npm install
npm test
npm run coverage
docker build -t my-app:latest .
docker run -p 3000:3000 my-app:latest
docker push my-app:latest

Deploying to Kubernetes

To deploy the Docker image, prepare these Kubernetes manifests:

Deployment: Defines Pods and ReplicaSets in k8s/deployment.yaml
Service: Exposes Pods internally via k8s/service.yaml
Ingress: Routes external HTTP traffic using k8s/ingress.yaml

Apply them in sequence:

kubectl apply -f k8s/deployment.yaml
kubectl apply -f k8s/service.yaml
kubectl apply -f k8s/ingress.yaml

Integration Testing on Dev

Once the resources are live, validate the deployment:

curl http://dev.my-app.example.com/health

A 200 OK response confirms that the application is operating correctly in the development cluster.

Note

Ensure your Kubernetes context is set to the development cluster:

kubectl config use-context dev-cluster

Manual Approval Gate

Before proceeding to production, implement a manual approval step in your CI/CD workflow. This prevents unintentional releases.

Warning

An administrator must review the integration test results and approve the release.
Skipping this step can lead to unverified changes reaching production.

Production Deployment

After approval, deploy to the production cluster using the same manifests:

Switch to the production context:

kubectl config use-context prod-cluster

Apply the manifests:

kubectl apply -f k8s/deployment.yaml
kubectl apply -f k8s/service.yaml
kubectl apply -f k8s/ingress.yaml

Run production integration tests:
```
curl http://my-app.example.com/health
```

Optionally, configure post-deployment alerts or monitoring checks to ensure reliability.

Next Steps

In the next lesson, we’ll cover Kubernetes fundamentals in depth and build automated workflow files for our CI/CD pipeline.

Links and References

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