KubeConnect: Node.js and MongoDB

This project demonstrates how to deploy a Node.js application on Kubernetes and connect it to a MongoDB database.

Kubernetes-App-Deployment.mov

Prerequisites

• Docker
• Kubernetes cluster (Minikube for local development)
• kubectl
• Node.js
• npm

Project Structure

.
├── app/
│   ├── index.js
│   └── package.json
├── k8s/
│   ├── mongodb-configmap.yaml
│   ├── mongodb-secret.yaml
│   ├── mongodb-deployment.yaml
│   ├── nodejs-deployment.yaml
│   └── node-app-service.yaml
├── Dockerfile
└── README.md

Steps

1. Create Kubernetes Configuration Files

Create the following YAML files in the k8s/ directory:

• mongodb-configmap.yaml: ConfigMap for MongoDB connection string
• mongodb-secret.yaml: Secret for MongoDB credentials
• mongodb-deployment.yaml: Deployment and Service for MongoDB
• nodejs-deployment.yaml: Deployment for Node.js application
• node-app-service.yaml: Service for Node.js application

---

2. Deploy MongoDB

1. Apply the MongoDB Secret:

   kubectl apply -f k8s/mongodb-secret.yaml

2. Apply the MongoDB ConfigMap:

   kubectl apply -f k8s/mongodb-configmap.yaml

3. Deploy MongoDB:

   kubectl apply -f k8s/mongodb-deployment.yaml

---

3. Dockerize the Node.js Application

1. Update your index.js to use the MongoDB connection string from the environment:

   const mongoUri = process.env.database_url;
   
   mongoose
     .connect(mongoUri, { useNewUrlParser: true, useUnifiedTopology: true })
     .then(() => console.log('Connected to MongoDB'))
     .catch((err) => console.error('Failed to connect to MongoDB:', err));

2. Create a Dockerfile in the project root:

   FROM node:18-alpine
   
   WORKDIR /app
   
   COPY package*.json ./
   
   RUN npm install
   
   COPY . .
   
   EXPOSE 3000
   
   CMD ["node", "index.js"]

3. Build the Docker image:

   docker build -t your-username/node-web-app .

4. Push the image to Docker Hub:

   docker push your-username/node-web-app

---

4. Deploy Node.js Application

1. Update nodejs-deployment.yaml with your Docker image:

   spec:
     containers:
     - name: nodejs
       image: your-username/node-app:latest

2. Apply the Node.js Deployment:

   kubectl apply -f k8s/nodejs-deployment.yaml

3. Apply the Node.js Service:

   kubectl apply -f k8s/nodejs-service.yaml

---

5. Verify Deployment

Check the status of your deployments:

kubectl get deployments
kubectl get pods
kubectl get services

---

6. Access the Application

For Minikube, use the following command to get the service URL:

minikube service nodejs-service

---

File Contents

mongodb-configmap.yaml

apiVersion: v1
kind: ConfigMap
metadata:
  name: mongodb-configmap
data:
  database_url: mongodb://$(MONGO_USER):$(MONGO_PASSWORD)@mongodb-service:27017/?authSource=admin

mongodb-secret.yaml

apiVersion: v1
kind: Secret
metadata:
  name: mongodb-secret
type: Opaque
stringData:
  mongo-root-username: your_username_here
  mongo-root-password: your_password_here

mongodb-deployment.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: mongodb-deployment
  labels:
    app: mongodb
spec:
  replicas: 1
  selector:
    matchLabels:
      app: mongodb
  template:
    metadata:
      labels:
        app: mongodb
    spec:
      containers:
      - name: mongodb
        image: mongo
        ports:
        - containerPort: 27017
        env:
        - name: MONGO_INITDB_ROOT_USERNAME
          valueFrom:
            secretKeyRef:
              name: mongodb-secret
              key: mongo-root-username
        - name: MONGO_INITDB_ROOT_PASSWORD
          valueFrom:
            secretKeyRef:
              name: mongodb-secret
              key: mongo-root-password
---
apiVersion: v1
kind: Service
metadata:
  name: mongodb-service
spec:
  selector:
    app: mongodb
  ports:
    - protocol: TCP
      port: 27017
      targetPort: 27017

nodejs-deployment.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nodejs-deployment
spec:
  replicas: 1
  selector:
    matchLabels:
      app: nodejs
  template:
    metadata:
      labels:
        app: nodejs
    spec:
      containers:
      - name: nodejs
        image: your-username/node-app:latest
        ports:
        - containerPort: 3000
        envFrom:
        - configMapRef:
            name: mongodb-configmap
        env:
        - name: MONGO_USER
          valueFrom:
            secretKeyRef:
              name: mongodb-secret
              key: mongo-root-username
        - name: MONGO_PASSWORD
          valueFrom:
            secretKeyRef:
              name: mongodb-secret
              key: mongo-root-password

node-app-service.yaml

apiVersion: v1
kind: Service
metadata:
  name: node-app-service
spec:
  selector:
    app: nodejs
  type: LoadBalancer
  ports:
    - protocol: TCP
      port: 80
      targetPort: 3000

---

Conclusion

This project demonstrates how to set up Kubernetes configurations, deploy MongoDB, containerize a Node.js application, and deploy it on Kubernetes with a connection to the MongoDB database. By following these steps, you can create a scalable and manageable deployment of your Node.js application.

This README provides clear instructions and a detailed walkthrough for deploying a Node.js application with MongoDB on Kubernetes.