zkt25/assignment2

Weather Web App - Kubernetes Deployment

This project deploys a full-stack weather web application to Kubernetes. It includes:

• A frontend website to search weather by city
• A backend PostgreSQL database for logging searches
• A Node.js API to connect the frontend to the database

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Application Description

• Frontend (weather.html): A responsive, modern web UI that shows current weather data using the OpenWeatherMap API.
• Backend (PostgreSQL): Stores weather search history via a weather_log table.
• API Server (Node.js): Receives weather data from the frontend and logs it to the PostgreSQL database.

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Containers Used

Container	Image	Description
weather-frontend	Custom Nginx-based	Serves the weather.html UI
postgres	postgres:15	Provides relational database backend
weather-api	Custom Node.js	API that logs weather data to PostgreSQL

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☸️ Kubernetes Objects

Object Type	File	Description
Namespace	(inside script)	Isolates resources under webapp-ns
Deployment	deployment.yaml	Manages frontend app
Deployment	deployment-api.yaml	Manages the Node.js API
StatefulSet	statefulset.yaml	Manages PostgreSQL instance with persistent volume
PersistentVolume	statefulset.yaml	Host-mounted volume for PostgreSQL data
PersistentVolumeClaim	statefulset.yaml	Requests storage for StatefulSet
Service	service.yaml	Exposes frontend via NodePort
Service	deployment-api.yaml	Exposes API via NodePort
Service	postgres-service.yaml	Internal ClusterIP service for PostgreSQL DNS resolution
ConfigMap	db-init-script	Stores the SQL init script for table creation

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Networking & Volumes

Virtual Networks:

• Kubernetes services provide internal DNS for postgres and weather-api-service.
• Frontend and API exposed externally using NodePort services.

Volumes:

• PersistentVolume and PersistentVolumeClaim ensure PostgreSQL data is retained.
• ConfigMap used to apply init-db.sql manually via psql.

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⚙️ Container Configurations

Frontend

• Dockerfile uses nginx:alpine
• Serves weather.html
• Exposed on port 80

Node.js API

• Built with Node.js 18
• Listens on port 3000
• Connects to PostgreSQL using service DNS postgres
• Accepts POST requests at /log

PostgreSQL

• postgres:15 with weatheruser, weatherpass, and weatherdb
• Table weather_log is created manually after StatefulSet starts

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How to Use the Application

1. Build Docker Images

./prepare-app.sh

2. Start the App (create namespace and apply all configs)

./start-app.sh

3. Manually Initialize the Database

kubectl exec -it -n webapp-ns statefulset/postgres -- psql -U weatheruser -d weatherdb

Paste this inside the prompt:

CREATE TABLE IF NOT EXISTS weather_log (
    id SERIAL PRIMARY KEY,
    city VARCHAR(100),
    temperature DECIMAL(5,2),
    description TEXT,
    timestamp TIMESTAMP DEFAULT CURRENT_TIMESTAMP
);

Exit with:

\q

4. View the App

minikube service weather-service -n webapp-ns

Or manually:

minikube ip
kubectl get svc -n webapp-ns

Then open:

http://<minikube-ip>:<frontend-nodeport>

5. Use the App

• Search for a city
• Weather appears
• Weather data is logged via API to PostgreSQL

6. View Logged Data

kubectl exec -it -n webapp-ns statefulset/postgres -- psql -U weatheruser -d weatherdb

SELECT * FROM weather_log ORDER BY timestamp DESC;

7. Stop and Clean Up

./stop-app.sh

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API Key Setup

• Register at OpenWeatherMap
• Replace the key in weather.html:

const apiKey = "YOUR_API_KEY";

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Conclusion

• Frontend fetches real-time weather from OpenWeatherMap
• Logs are POSTed to backend and stored in PostgreSQL

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