Introduction

In this article, we will explore how to deploy a Node.js application using Kustomize on a Minikube cluster. We will cover the project structure, Dockerfile setup, Kubernetes manifests, and how to use Kustomize to manage different configurations for development, staging, and production environments. We will also discuss the advantages of using Kustomize over other alternatives.

Prerequisites

Before we begin, ensure you have the following installed on your machine:

Project Structure

Here is the structure of our project:

profile-app/ structure

profile-app/
├── config/
│   └── config.json
├── k8s/
│   ├── base/
│   │   ├── deployment.yaml
│   │   ├── service.yaml
│   │   ├── pvc.yaml
│   │   ├── namespace.yaml
│   │   └── kustomization.yaml
│   └── overlays/
│       ├── dev/
│       │   ├── config.json
│       │   └── kustomization.yaml
│       ├── prod/
│       │   ├── config.json
│       │   └── kustomization.yaml
│       └── staging/
│           ├── config.json
│           └── kustomization.yaml
├── app.js
├── package.json
├── Dockerfile
└── docs/
    └── readme.md

Application Code

`app.js`

app.js

1const express = require("express");
2const fs = require("fs");
3const app = express();
4const PORT = process.env.PORT || 3001;
5// Read the mounted config file
6const CONFIG_PATH = "./config/config.json";
7let config = { name: "Noel Bansikah", role: "DevOps Engineer", nameColor: "black", roleColor: "gray", environment: "development" };
8// Check if the config file exists
9if (fs.existsSync(CONFIG_PATH)) {
10  config = JSON.parse(fs.readFileSync(CONFIG_PATH, "utf-8"));
11}
12// Define a color map for meaningful colors
13const colorMap = {
14  black: "#000000",
15  gray: "#6c757d",
16  blue: "#007BFF",
17  yellow: "#FFC107",
18  red: "#DC3545",
19  green: "#28A745"
20};
21// Get the colors from the config or default to black and gray
22const nameColor = colorMap[config.nameColor] || colorMap.black;
23const roleColor = colorMap[config.roleColor] || colorMap.gray;
24app.get("/", (req, res) => {
25  res.send(`
26    <html>
27      <body style="background-color: white; text-align: center; padding: 50px;">
28        <h1 style="color: ${nameColor};">Hello, I am ${config.name} 🚀</h1>
29        <h2 style="color: ${roleColor};">Role: ${config.role}</h2>
30        <h3>Environment: ${config.environment}</h3>
31        <p>GitHub: <a href="https://github.com/bansikah22">bansikah22</a></p>
32        <p>GitLab: <a href="https://gitlab.com/tandapnoelbansikah">bansikah22</a></p>
33        <p>LinkedIn: <a href="https://linkedin.com/in/tandapnoelbansikah">bansikah22</a></p>
34      </body>
35    </html>
36  `);
37});
38app.listen(PORT, () => console.log(`Server running on port ${PORT}...`));

`Dockerfile`

Dockerfile

1# Stage 1: Build stage
2FROM node:18-alpine AS build
3WORKDIR /app
4COPY package.json package-lock.json ./
5RUN npm ci --production
6COPY app.js ./
7# Stage 2: Production stage
8FROM node:18-slim
9WORKDIR /app
10RUN apt-get update && apt-get install -y curl && rm -rf /var/lib/apt/lists/*
11COPY --from=build /app/node_modules /app/node_modules
12COPY --from=build /app/app.js /app/app.js
13CMD ["node", "app.js"]
14EXPOSE 3001

Building and Pushing the Docker Image

To build and push the Docker image to Docker Hub, follow these steps:

Build the Docker image:

Bash

docker build -t <your-dockerhub-username>/profile-app:latest .

2. Push the Docker image to Docker Hub:

Bash

docker push <your-dockerhub-username>/profile-app:latest

Replace <your-dockerhub-username> with your actual Docker Hub username.

Kubernetes Manifests

Base Manifests

The base directory contains the common configuration that is shared across all environments. This includes the deployment, service, PVC, and namespace definitions.

`k8s/base/deployment.yaml`

k8s/base/deployment.yaml

1apiVersion: apps/v1
2kind: Deployment
3metadata:
4  name: profile-app
5spec:
6  replicas: 1
7  selector:
8    matchLabels:
9      app: profile-app
10  template:
11    metadata:
12      labels:
13        app: profile-app
14    spec:
15      containers:
16      - name: profile-app
17        image: <your-dockerhub-username>/profile-app:latest
18        imagePullPolicy: Always
19        ports:
20        - containerPort: 3001
21        volumeMounts:
22        - name: config-volume
23          mountPath: /app/config
24          subPath: config.json
25          readOnly: false
26      volumes:
27      - name: config-volume
28        configMap:
29          name: profile-app-config

`k8s/base/service.yaml`

k8s/base/service.yaml

1apiVersion: v1
2kind: Service
3metadata:
4  name: profile-service
5spec:
6  selector:
7    app: profile-app
8  ports:
9    - protocol: TCP
10      port: 80
11      targetPort: 3001
12  type: ClusterIP

`k8s/base/pvc.yaml`

k8s/base/pvc.yaml

1apiVersion: v1
2kind: PersistentVolumeClaim
3metadata:
4  name: profile-app-pvc
5spec:
6  accessModes:
7    - ReadWriteOnce
8  resources:
9    requests:
10      storage: 1Gi

`k8s/base/namespace.yaml`

k8s/base/namespace.yaml

1apiVersion: v1
2kind: Namespace
3metadata:
4  name: profile-app

`k8s/base/kustomization.yaml`

The kustomization.yaml file in the base directory defines the resources and images used in the base configuration.

k8s/base/kustomization.yaml

1resources:
2  - deployment.yaml
3  - service.yaml
4  - pvc.yaml
5  - namespace.yaml
6
7images:
8  - name: profile-app
9    newName: <your-dockerhub-username>/profile-app
10    newTag: latest

Overlays

The overlays directory contains environment-specific configurations. Each environment (dev, prod, staging) has its own directory with a config.json file and a kustomization.yaml file.

`k8s/overlays/dev/config.json`

k8s/overlays/dev/config.json

1{
2  "name": "Noel Bansikah",
3  "role": "DevOps Engineer and Software Developer",
4  "nameColor": "blue",
5  "roleColor": "green",
6  "environment": "development"
7}

`k8s/overlays/dev/kustomization.yaml`

k8s/overlays/dev/Kustomization.json

1namespace: dev
2resources:
3  - ../../base
4
5configMapGenerator:
6  - name: profile-app-config
7    files:
8      - config.json=config.json

`k8s/overlays/prod/config.json`

k8s/overlays/prod/config.json

1{
2  "name": "Noel Bansikah",
3  "role": "Senior DevOps Engineer",
4  "nameColor": "red",
5  "roleColor": "yellow",
6  "environment": "production"
7}

`k8s/overlays/prod/kustomization.yaml`

k8s/overlays/prod/kustomization.json

1namespace: prod
2resources:
3  - ../../base
4
5configMapGenerator:
6  - name: profile-app-config
7    files:
8      - config.json=config.json

`k8s/overlays/staging/config.json`

k8s/overlays/staging/config.json

1{
2  "name": "Noel Bansikah",
3  "role": "DevOps Engineer",
4  "nameColor": "green",
5  "roleColor": "blue",
6  "environment": "staging"
7}

`k8s/overlays/staging/kustomization.yaml`

k8s/overlays/staging/kustomization.json

1namespace: staging
2resources:
3  - ../../base
4
5configMapGenerator:
6  - name: profile-app-config
7    files:
8      - config.json=config.json

Using Kustomize

Kustomize is a tool that allows you to customize Kubernetes resource configurations. It provides a way to manage different configurations for different environments without duplicating YAML files. Kustomize is built into kubectl, making it easy to use.

Advantages of Kustomize

Declarative Management: Kustomize allows you to manage Kubernetes resources declaratively.
Environment-Specific Configurations: You can manage different configurations for different environments using overlays.
No Templating: Kustomize does not use templating, making it easier to understand and maintain.
Built into kubectl: Kustomize is integrated into kubectl, so you don't need to install any additional tools.

Alternatives to Kustomize

Helm: Helm is a package manager for Kubernetes that uses templating to manage configurations. While Helm is powerful and widely used, it can be more complex to manage compared to Kustomize.
Ksonnet: Ksonnet was another tool for managing Kubernetes configurations, but it has been deprecated in favor of Kustomize and Helm.

Why We Prefer Kustomize

We prefer Kustomize for our application because it provides a simple and declarative way to manage configurations for different environments. It is easy to use, integrated into kubectl, and does not require templating, making it easier to maintain.

Deploying the Application

1. Start Minikube

Bash

minikube start

2. Deploy to Kubernetes

// title: Bash // copy: true // lines: False // maxLines: 10 kubectl apply -k k8s/overlays/dev kubectl apply -k k8s/overlays/prod kubectl apply -k k8s/overlays/staging

3. Test the App

Port Forwarding

// title: Bash // copy: true // lines: False // maxLines: 10 kubectl port-forward -n dev svc/profile-service 8080:80 kubectl port-forward -n staging svc/profile-service 8081:80 kubectl port-forward -n prod svc/profile-service 8082:80

Access the App

Open your browser and navigate to:

Development: http://localhost:8080

Staging: http://localhost:8081
Production: http://localhost:8082

4. Verify Deployments

Bash

kubectl get pods -n dev
kubectl get pods -n staging
kubectl get pods -n prod

kubectl get services -n dev
kubectl get services -n staging
kubectl get services -n prod

5. Check Logs to Confirm Colors

Bash

kubectl logs -n dev deployment/profile-app
kubectl logs -n staging deployment/profile-app
kubectl logs -n prod deployment/profile-app

6. Test Persistent Storage

Check the Volume Mount

Bash

kubectl exec -n dev -it $(kubectl get pod -n dev -l app=profile-app -o jsonpath='{.items[0].metadata.name}') -- ls /app/config

Restart the Pod & Check if Config Persists

Bash

kubectl delete pod -n dev -l app=profile-app
kubectl get pods -n dev -w

7. Verify the Updated Config

Bash

kubectl exec -n dev -it $(kubectl get pod -n dev -l app=profile-app -o jsonpath='{.items[0].metadata.name}') -- curl profile-service

Open http://localhost:8080 in your browser to see the updated configuration! 🎉

Conclusion

In this article, we explored how to deploy a Node.js application using Kustomize on a Minikube cluster. We covered the project structure, Dockerfile setup, Kubernetes manifests, and how to use Kustomize to manage different configurations for development, staging, and production environments. We also discussed the advantages of using Kustomize over other alternatives. LInk to the Code

If you have any questions or face any challenges, feel free to ask in the comments section below. Happy coding!

References

Happy coding! 🎉

Introduction

Prerequisites

Project Structure

Application Code

app.js

Dockerfile

Building and Pushing the Docker Image

Build the Docker image:

2. Push the Docker image to Docker Hub:

Kubernetes Manifests

Base Manifests

k8s/base/deployment.yaml

k8s/base/service.yaml

k8s/base/pvc.yaml

k8s/base/namespace.yaml

k8s/base/kustomization.yaml

Overlays

k8s/overlays/dev/config.json

k8s/overlays/dev/kustomization.yaml

k8s/overlays/prod/config.json

k8s/overlays/prod/kustomization.yaml

k8s/overlays/staging/config.json

k8s/overlays/staging/kustomization.yaml

Using Kustomize

Advantages of Kustomize

Alternatives to Kustomize

Why We Prefer Kustomize

Deploying the Application

1. Start Minikube

2. Deploy to Kubernetes

3. Test the App

Port Forwarding

Access the App

4. Verify Deployments

5. Check Logs to Confirm Colors

6. Test Persistent Storage

Check the Volume Mount

Restart the Pod & Check if Config Persists

7. Verify the Updated Config

Conclusion

References

`app.js`

`Dockerfile`

`k8s/base/deployment.yaml`

`k8s/base/service.yaml`

`k8s/base/pvc.yaml`

`k8s/base/namespace.yaml`

`k8s/base/kustomization.yaml`

`k8s/overlays/dev/config.json`

`k8s/overlays/dev/kustomization.yaml`

`k8s/overlays/prod/config.json`

`k8s/overlays/prod/kustomization.yaml`

`k8s/overlays/staging/config.json`

`k8s/overlays/staging/kustomization.yaml`