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z1/README.md

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+# Docker Web Application Deployment (Without Docker Compose)
+
+## Overview
+This project deploys a multi-container Docker application consisting of:
+- **Flask Web App:** A Python Flask application that connects to a PostgreSQL database.
+- **PostgreSQL Database:** Uses the official PostgreSQL image with persistent storage via a named volume.
+
+Both containers communicate over a custom Docker network (`app_network`).
+
+## Required Software
+- **Operating System:** Linux (with Docker support)
+- **Docker:** Installed and configured
+- **Bash:** For running the provided scripts
+
+## Components
+
+### Flask Web Application
+- **Image:** Built locally from the Dockerfile in the `app/` folder.
+- **Container Name:** `flask_app`
+- **Port Mapping:** Host port `5000` mapped to container port `5000`.
+- **Environment Variables:** Set via the `docker run` command to point to the database.
+
+### PostgreSQL Database
+- **Image:** `postgres:13`
+- **Container Name:** `postgres_db`
+- **Environment Variables:**
+  - `POSTGRES_USER=user`
+  - `POSTGRES_PASSWORD=password`
+  - `POSTGRES_DB=sampledb`
+- **Volume:** Named volume `pgdata` is mounted at `/var/lib/postgresql/data` for persistent storage.
+
+### Virtual Network and Volume
+- **Network:** `app_network` – A custom Docker bridge network for inter-container communication.
+- **Volume:** `pgdata` – Persists PostgreSQL data between container restarts.
+
+## How to prepare, run, pause and delete the application
+# Step 1: Prepare the application
+# This will create the necessary volume, network, and build the Flask image.
+./prepare-app.sh
+
+# Step 2: Run the application
+# This will start the PostgreSQL database and Flask web application containers.
+./start-app.sh
+
+# Step 3: Stop the application
+# It will stop the containers
+./stop-app.sh
+
+# Step 5: Remove the application
+# This will stop and remove the containers, network, and volume.
+./remove-app.sh
+
+
+## How to view the application on the web
+
+# Step 1: Ensure that the Flask application is running
+# Make sure that the application has been started by running the ./start-app.sh script.
+# The Flask application should be accessible at http://localhost:5000.
+
+# Step 2: Open a web browser and enter the following URL:
+http://localhost:5000
+

z1/prepare-app.sh

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+#!/bin/bash
+echo "Preparing the application..."
+
+# Create the Docker volume for PostgreSQL data persistence if it doesn't exist.
+docker volume create pgdata
+
+# Create the custom Docker network (if it already exists, an error is suppressed).
+docker network create app_network 2>/dev/null || echo "Network app_network already exists."
+
+# Build the Flask application image from the Dockerfile in the ./app folder.
+docker build -t flask_app_image ./app
+
+echo "Preparation completed."

z1/remove-app.sh

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+#!/bin/bash
+echo "Removing the application..."
+
+# Remove the containers forcefully.
+docker rm -f flask_app postgres_db
+
+# Remove the custom network and volume if they exist.
+docker network rm app_network 2>/dev/null || echo "Network app_network already removed."
+docker volume rm pgdata 2>/dev/null || echo "Volume pgdata already removed."
+
+echo "Application removed."

z1/start-app.sh

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+#!/bin/bash
+echo "Starting the application"
+
+# Run PostgreSQL container
+docker run -d --name postgres_db \
+  --network app_network \
+  -e POSTGRES_USER=user \
+  -e POSTGRES_PASSWORD=password \
+  -e POSTGRES_DB=sampledb \
+  -v pgdata:/var/lib/postgresql/data \
+  --restart always \
+  postgres:13
+# Wait a few seconds to ensure PostgreSQL starts before the Flask app connects.
+sleep 10
+
+# Run Flask application container
+docker run -d --name flask_app \
+  --network app_network \
+  -p 5000:5000 \
+  --restart always \
+  -e DB_HOST=postgres_db \
+  -e POSTGRES_USER=user \
+  -e POSTGRES_PASSWORD=password \
+  -e POSTGRES_DB=sampledb \
+  flask_app_image
+
+echo "The application is available at http://localhost:5000"

z1/stop-app.sh

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+#!/bin/bash
+echo "Stopping the application"
+
+docker stop flask_app postgres_db
+
+echo "Application stopped."