#  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

---

##  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.

---

##  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     |

---

## ☸️ 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                        |

---

##  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`.

---

## ⚙️ 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

---

##  How to Use the Application

### 1. Build Docker Images

```bash
./prepare-app.sh
```

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

```bash
./start-app.sh
```

### 3. Manually Initialize the Database

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

Paste this inside the prompt:

```sql
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:
```sql
\q
```

### 4. View the App

```bash
minikube service weather-service -n webapp-ns
```

Or manually:

```bash
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

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

```sql
SELECT * FROM weather_log ORDER BY timestamp DESC;
```

### 7. Stop and Clean Up

```bash
./stop-app.sh
```

---

##  API Key Setup

- Register at [OpenWeatherMap](https://openweathermap.org/api)
- Replace the key in `weather.html`:

```js
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

---