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z1/README.md

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+# NitheeshWork — Multi-Container Task Manager
+
+A web-based task management application deployed with Docker Compose across **5 isolated containers**, featuring persistent storage, a REST API with Redis caching, and a database management UI.
+
+---
+
+## What the Application Does
+
+NitheeshWork is a kanban-style task manager where you can:
+
+- Create, edit, and delete tasks
+- Assign each task a **status** (To Do / In Progress / Done) and **priority** (Low / Medium / High)
+- View live statistics showing task counts per status
+- Filter tasks by priority
+- Browse and manage the database directly via pgAdmin
+- Call the REST API directly from any HTTP client
+
+The backend caches the statistics endpoint in Redis (10-second TTL) to reduce database load. The frontend shows a ⚡ indicator when a response is served from cache.
+
+---
+
+## Required Software
+
+| Software | Minimum Version | Purpose |
+|---|---|---|
+| Docker Engine | 24.0+ | Container runtime |
+| Docker Compose plugin | v2.0+ | Multi-container orchestration |
+| Linux (Ubuntu/Debian recommended) | — | Host operating system |
+
+### Install Docker on Ubuntu/Debian
+
+```bash
+sudo apt update
+sudo apt install -y ca-certificates curl gnupg
+sudo install -m 0755 -d /etc/apt/keyrings
+curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo gpg --dearmor -o /etc/apt/keyrings/docker.gpg
+echo "deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.gpg] \
+  https://download.docker.com/linux/ubuntu $(. /etc/os-release && echo "$VERSION_CODENAME") stable" \
+  | sudo tee /etc/apt/sources.list.d/docker.list
+sudo apt update
+sudo apt install -y docker-ce docker-ce-cli containerd.io docker-compose-plugin
+sudo systemctl start docker && sudo systemctl enable docker
+sudo usermod -aG docker $USER && newgrp docker
+```
+
+---
+
+## Containers
+
+| Container | Image | Port | Role |
+|---|---|---|---|
+| `nitheeshwork-postgres` | postgres:16-alpine | 5432 (internal) | PostgreSQL relational database — stores all tasks |
+| `nitheeshwork-redis` | redis:7-alpine | 6379 (internal) | Redis in-memory cache — caches API stats responses |
+| `nitheeshwork-backend` | built locally | 4000 | Node.js/Express REST API — business logic layer |
+| `nitheeshwork-frontend` | nginx:1.25-alpine | 8080 | Serves the HTML/JS frontend and proxies /api/ to backend |
+| `nitheeshwork-pgadmin` | dpage/pgadmin4 | 5050 | Web UI for browsing and querying PostgreSQL |
+
+### Container Configuration Details
+
+**postgres** — configured via environment variables (`POSTGRES_DB`, `POSTGRES_USER`, `POSTGRES_PASSWORD`). Has a healthcheck using `pg_isready` so dependent containers wait until the DB is truly ready before starting.
+
+**redis** — started with `--appendonly yes` so data is persisted to disk (AOF mode) rather than lost on restart.
+
+**backend** — custom Node.js image built from `./backend/Dockerfile`. Receives database and cache connection details via environment variables. Automatically seeds 6 sample tasks on first startup if the table is empty. Configured with `restart: unless-stopped`.
+
+**frontend** — vanilla nginx serving `./frontend/index.html` as a static file. A custom `nginx/default.conf` adds a reverse proxy rule: any request to `/api/` is forwarded to the backend container on port 4000. This allows the browser to talk to one origin (port 8080) for both UI and API.
+
+**pgadmin** — configured in desktop mode (`SERVER_MODE=False`) so no extra login infrastructure is needed. Email and password set via environment variables.
+
+---
+
+## Virtual Networks
+
+| Network | Driver | Purpose |
+|---|---|---|
+| `nitheeshwork-net` | bridge | Private internal network connecting all 5 containers. Containers address each other by service name (e.g. `postgres`, `redis`). No external access except through published ports. |
+
+All inter-container communication happens over this network. The backend connects to `postgres:5432` and `redis:6379` using Docker's internal DNS — these hostnames are not reachable from outside the network.
+
+---
+
+## Named Volumes
+
+| Volume | Mounted In | What It Stores |
+|---|---|---|
+| `nitheeshwork-postgres-data` | `/var/lib/postgresql/data` | All PostgreSQL data files — tasks table and schema |
+| `nitheeshwork-redis-data` | `/data` | Redis AOF persistence file — survives restarts |
+| `nitheeshwork-pgadmin-data` | `/var/lib/pgadmin` | pgAdmin saved server connections and session data |
+
+Stopping the application with `stop-app.sh` does **not** remove these volumes. Data persists across restarts and even configuration changes. Only `remove-app.sh` deletes them.
+
+---
+
+## Instructions
+
+### Prepare (first time only)
+
+```bash
+chmod +x prepare-app.sh start-app.sh stop-app.sh remove-app.sh
+./prepare-app.sh
+```
+
+This builds the backend Docker image, creates the `nitheeshwork-net` network, and provisions all three named volumes.
+
+### Start
+
+```bash
+./start-app.sh
+```
+
+Starts all 5 containers. All containers are configured with `restart: unless-stopped` — they will automatically restart if they crash, and will start again after a system reboot (as long as the Docker daemon is running).
+
+### Pause (stop without losing data)
+
+```bash
+./stop-app.sh
+```
+
+Stops all containers. Named volumes and data are fully preserved. Resume any time with `./start-app.sh`.
+
+### Remove everything
+
+```bash
+./remove-app.sh
+```
+
+Asks for confirmation, then removes all containers, volumes, the network, and the built image. This is irreversible — all task data will be deleted.
+
+---
+
+## Viewing the Application in a Browser
+
+| URL | What you see |
+|---|---|
+| http://localhost:8080 | Main NitheeshWork task manager UI |
+| http://localhost:4000/api/tasks | Raw JSON API — list of all tasks |
+| http://localhost:4000/health | Service health check (JSON) |
+| http://localhost:5050 | pgAdmin database management UI |
+
+### Connecting pgAdmin to PostgreSQL
+
+1. Open http://localhost:5050
+2. Login: `admin@nitheeshwork.com` / `adminpass`
+3. Click **Add New Server**
+4. **General tab** → Name: `nitheeshwork`
+5. **Connection tab**:
+   - Host: `postgres`
+   - Port: `5432`
+   - Database: `taskdb`
+   - Username: `taskuser`
+   - Password: `taskpass`
+6. Click **Save**
+7. Browse to: `Servers → nitheeshwork → Databases → taskdb → Schemas → public → Tables → tasks`
+
+---
+
+## REST API Reference
+
+Base URL: `http://localhost:4000/api`
+
+| Method | Endpoint | Description |
+|---|---|---|
+| GET | `/tasks` | List all tasks |
+| GET | `/tasks?priority=high` | Filter by priority (low/medium/high) |
+| GET | `/tasks?status=todo` | Filter by status (todo/in-progress/done) |
+| GET | `/tasks/:id` | Get a single task |
+| POST | `/tasks` | Create a new task |
+| PUT | `/tasks/:id` | Update a task |
+| DELETE | `/tasks/:id` | Delete a task |
+| GET | `/stats` | Task counts by status (Redis cached) |
+| GET | `/health` | Returns postgres + redis health status |
+
+Example — create a task:
+```bash
+curl -X POST http://localhost:4000/api/tasks \
+  -H "Content-Type: application/json" \
+  -d '{"title":"My task","description":"Details here","status":"todo","priority":"high"}'
+```
+
+---
+
+## File Structure
+
+```
+nitheeshwork/
+├── backend/
+│   ├── Dockerfile          ← Node.js image definition
+│   ├── package.json        ← Dependencies (express, pg, redis, cors)
+│   └── server.js           ← Express REST API with all endpoints
+├── frontend/
+│   └── index.html          ← Single-page task manager UI (HTML/CSS/JS)
+├── nginx/
+│   └── default.conf        ← Nginx config: static files + /api/ proxy
+├── docker-compose.yaml     ← All 5 service definitions
+├── prepare-app.sh          ← Build image, create network and volumes
+├── start-app.sh            ← Start all containers
+├── stop-app.sh             ← Stop containers, preserve data
+├── remove-app.sh           ← Full teardown including volumes
+└── README.md               ← This file
+```
+
+---
+
+## Resources Used
+
+| Resource | URL |
+|---|---|
+| Docker Engine documentation | https://docs.docker.com/engine/ |
+| Docker Compose documentation | https://docs.docker.com/compose/ |
+| PostgreSQL 16 Docker image | https://hub.docker.com/_/postgres |
+| Redis 7 Docker image | https://hub.docker.com/_/redis |
+| Nginx Docker image | https://hub.docker.com/_/nginx |
+| pgAdmin 4 Docker image | https://hub.docker.com/r/dpage/pgadmin4 |
+| Node.js 20 Alpine image | https://hub.docker.com/_/node |
+| Express.js documentation | https://expressjs.com/ |
+| node-postgres (pg) library | https://node-postgres.com/ |
+| node-redis library | https://github.com/redis/node-redis |
+
+---
+
+## Use of Artificial Intelligence
+
+This project was designed and implemented with the assistance of **Claude** (claude.ai), an AI assistant made by Anthropic.
+
+### AI Agent Used
+
+| Agent | Model | Role |
+|---|---|---|
+| Claude (claude.ai) | Claude Sonnet 4.6 | Full application design and code generation |
+
+### How AI Was Used
+
+- **Application architecture** — Claude designed the 5-service Docker Compose architecture, selecting appropriate images and deciding how services should communicate.
+- **Backend code** — The entire `server.js` Express API (endpoints, PostgreSQL queries, Redis caching logic, health checks, seed data) was written by Claude.
+- **Frontend code** — The complete `index.html` single-page application (UI layout, CSS styling, JavaScript fetch calls, live health indicators) was generated by Claude.
+- **Docker configuration** — All Dockerfiles, `docker-compose.yaml`, and nginx configuration were created by Claude.
+- **Shell scripts** — All four bash scripts (`prepare-app.sh`, `start-app.sh`, `stop-app.sh`, `remove-app.sh`) were written by Claude.
+- **Debugging** — Claude diagnosed and fixed issues encountered during deployment (network label conflict, pgAdmin email validation error).
+- **Documentation** — This README was written by Claude based on the actual implementation.
+
+All code was verified by running it on an Ubuntu Linux system inside a VMware virtual machine.

z1/docker-compose.yaml

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+services:
+
+  # ── 1. PostgreSQL Database ──────────────────────────────────────────────────
+  postgres:
+    image: postgres:16-alpine
+    container_name: nitheeshwork-postgres
+    restart: unless-stopped
+    environment:
+      POSTGRES_DB: taskdb
+      POSTGRES_USER: taskuser
+      POSTGRES_PASSWORD: taskpass
+    volumes:
+      - postgres_data:/var/lib/postgresql/data
+    networks:
+      - nitheeshwork-net
+    healthcheck:
+      test: ["CMD-SHELL", "pg_isready -U taskuser -d taskdb"]
+      interval: 10s
+      timeout: 5s
+      retries: 5
+
+  # ── 2. Redis Cache ──────────────────────────────────────────────────────────
+  redis:
+    image: redis:7-alpine
+    container_name: nitheeshwork-redis
+    restart: unless-stopped
+    command: redis-server --appendonly yes
+    volumes:
+      - redis_data:/data
+    networks:
+      - nitheeshwork-net
+    healthcheck:
+      test: ["CMD", "redis-cli", "ping"]
+      interval: 10s
+      timeout: 5s
+      retries: 5
+
+  # ── 3. Node.js/Express Backend API ─────────────────────────────────────────
+  backend:
+    build:
+      context: ./backend
+      dockerfile: Dockerfile
+    container_name: nitheeshwork-backend
+    restart: unless-stopped
+    environment:
+      POSTGRES_HOST: postgres
+      POSTGRES_DB: taskdb
+      POSTGRES_USER: taskuser
+      POSTGRES_PASSWORD: taskpass
+      REDIS_HOST: redis
+      PORT: 4000
+    ports:
+      - "4000:4000"
+    depends_on:
+      postgres:
+        condition: service_healthy
+      redis:
+        condition: service_healthy
+    networks:
+      - nitheeshwork-net
+
+  # ── 4. Nginx – Frontend + Reverse Proxy ────────────────────────────────────
+  frontend:
+    image: nginx:1.25-alpine
+    container_name: nitheeshwork-frontend
+    restart: unless-stopped
+    ports:
+      - "8080:80"
+    volumes:
+      - ./frontend:/usr/share/nginx/html:ro
+      - ./nginx/default.conf:/etc/nginx/conf.d/default.conf:ro
+    depends_on:
+      - backend
+    networks:
+      - nitheeshwork-net
+
+  # ── 5. pgAdmin – Database Web UI ───────────────────────────────────────────
+  pgadmin:
+    image: dpage/pgadmin4:latest
+    container_name: nitheeshwork-pgadmin
+    restart: unless-stopped
+    environment:
+      PGADMIN_DEFAULT_EMAIL: admin@nitheeshwork.com
+      PGADMIN_DEFAULT_PASSWORD: adminpass
+      PGADMIN_CONFIG_SERVER_MODE: "False"
+      PGADMIN_CONFIG_MASTER_PASSWORD_REQUIRED: "False"
+    volumes:
+      - pgadmin_data:/var/lib/pgadmin
+    ports:
+      - "5050:80"
+    depends_on:
+      - postgres
+    networks:
+      - nitheeshwork-net
+
+volumes:
+  postgres_data:
+    name: nitheeshwork-postgres-data
+  redis_data:
+    name: nitheeshwork-redis-data
+  pgadmin_data:
+    name: nitheeshwork-pgadmin-data
+
+networks:
+  nitheeshwork-net:
+    driver: bridge

z1/prepare-app.sh

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+#!/usr/bin/env bash
+# ============================================================
+# prepare-app.sh – Build images, create network & volumes
+# ============================================================
+set -euo pipefail
+
+echo "╔══════════════════════════════════════════════╗"
+echo "║      NitheeshWork – Prepare Application      ║"
+echo "╚══════════════════════════════════════════════╝"
+
+cd "$(dirname "$0")"
+
+# ── 1. Docker network ────────────────────────────────────────
+echo ""
+echo "▸ Creating Docker network: nitheeshwork-net"
+docker network inspect nitheeshwork-net >/dev/null 2>&1 \
+  && echo "  Network already exists, skipping." \
+  || docker network create nitheeshwork-net
+
+# ── 2. Named volumes ─────────────────────────────────────────
+echo ""
+echo "▸ Creating named volumes…"
+for vol in nitheeshwork-postgres-data nitheeshwork-redis-data nitheeshwork-pgadmin-data; do
+  docker volume inspect "$vol" >/dev/null 2>&1 \
+    && echo "  Volume $vol already exists, skipping." \
+    || docker volume create "$vol" && echo "  Created: $vol"
+done
+
+# ── 3. Build backend image ───────────────────────────────────
+echo ""
+echo "▸ Building backend Docker image…"
+docker build -t nitheeshwork-backend:latest ./backend
+
+echo ""
+echo "✔  Preparation complete."
+echo "   Run ./start-app.sh to start all services."

z1/remove-app.sh

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+#!/usr/bin/env bash
+# ============================================================
+# remove-app.sh – Remove ALL NitheeshWork containers, images,
+#                  volumes, and network (full cleanup)
+# ============================================================
+set -euo pipefail
+
+echo "╔══════════════════════════════════════════════╗"
+echo "║      NitheeshWork – Remove Application       ║"
+echo "╚══════════════════════════════════════════════╝"
+echo ""
+echo "⚠  WARNING: This will delete all data, including"
+echo "   the PostgreSQL database and Redis cache."
+echo ""
+read -rp "   Are you sure? Type 'yes' to confirm: " confirm
+[[ "$confirm" == "yes" ]] || { echo "Aborted."; exit 0; }
+
+cd "$(dirname "$0")"
+
+echo ""
+echo "▸ Stopping and removing containers…"
+docker compose down --remove-orphans 2>/dev/null || true
+
+echo ""
+echo "▸ Removing named volumes…"
+for vol in nitheeshwork-postgres-data nitheeshwork-redis-data nitheeshwork-pgadmin-data; do
+  docker volume rm "$vol" 2>/dev/null && echo "  Removed: $vol" || echo "  Volume $vol not found, skipping."
+done
+
+echo ""
+echo "▸ Removing Docker network…"
+docker network rm nitheeshwork-net 2>/dev/null && echo "  Removed: nitheeshwork-net" || echo "  Network not found, skipping."
+
+echo ""
+echo "▸ Removing built images…"
+docker rmi nitheeshwork-backend:latest 2>/dev/null && echo "  Removed: nitheeshwork-backend:latest" || echo "  Image not found, skipping."
+
+echo ""
+echo "✔  All NitheeshWork resources have been removed."

z1/start-app.sh

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+#!/usr/bin/env bash
+# ============================================================
+# start-app.sh – Start all NitheeshWork services
+# ============================================================
+set -euo pipefail
+
+echo "╔══════════════════════════════════════════════╗"
+echo "║       NitheeshWork – Start Application       ║"
+echo "╚══════════════════════════════════════════════╝"
+
+cd "$(dirname "$0")"
+
+echo ""
+echo "▸ Starting services with docker compose…"
+docker compose up -d --remove-orphans
+
+echo ""
+echo "▸ Waiting for services to become healthy…"
+sleep 6
+
+docker compose ps
+
+echo ""
+echo "╔══════════════════════════════════════════════════════╗"
+echo "║              NitheeshWork is ready!                  ║"
+echo "╠══════════════════════════════════════════════════════╣"
+echo "║  🌐 Web App (frontend)   →  http://localhost:8080    ║"
+echo "║  🔌 REST API (backend)   →  http://localhost:4000    ║"
+echo "║  🗄️  pgAdmin (DB UI)     →  http://localhost:5050    ║"
+echo "║                                                      ║"
+echo "║  pgAdmin login: admin@nitheeshwork.com / adminpass   ║"
+echo "║  PostgreSQL:    host=postgres  db=taskdb             ║"
+echo "║                 user=taskuser  pass=taskpass         ║"
+echo "╚══════════════════════════════════════════════════════╝"

z1/stop-app.sh

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+#!/usr/bin/env bash
+# ============================================================
+# stop-app.sh – Stop all NitheeshWork services (data preserved)
+# ============================================================
+set -euo pipefail
+
+echo "╔══════════════════════════════════════════════╗"
+echo "║       NitheeshWork – Stop Application        ║"
+echo "╚══════════════════════════════════════════════╝"
+
+cd "$(dirname "$0")"
+
+echo ""
+echo "▸ Stopping all services (volumes and data are preserved)…"
+docker compose stop
+
+echo ""
+echo "✔  All services stopped."
+echo "   Data in volumes is preserved."
+echo "   Run ./start-app.sh to resume."