Flask Calculator - Dockerized

Overview

This is a simple Flask-based web application that performs basic arithmetic operations (addition, subtraction, multiplication, division). The application is containerized using Docker and deployed on an AWS EC2 instance.

Features

• Web-based calculator UI (HTML, JavaScript, and Flask backend)
• Dockerized for easy deployment
• Hosted on an AWS EC2 instance
• Publicly available on Docker Hub

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Prerequisites

Before you begin, ensure you have the following:

• An AWS EC2 instance (Amazon Linux 2 or Ubuntu)
• Docker installed on the EC2 instance
• A Docker Hub account
• Git installed on the EC2 instance

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Step 1: Launch an EC2 Instance

1. Go to the AWS Console, navigate to EC2, and launch an instance.
2. Select Amazon Linux 2 or Ubuntu as your OS.
3. Choose an instance type (t2.micro for free-tier eligibility).
4. Configure security group:
   • Allow port 22 (SSH) for remote access.
   • Allow port 5000 (Flask app) for HTTP access.
5. Launch the instance and connect via SSH:

   ssh -i your-key.pem ec2-user@your-ec2-ip

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Step 2: Install Docker on EC2

For Amazon Linux 2:

sudo yum update -y
sudo yum install docker -y
sudo systemctl start docker
sudo systemctl enable docker
sudo usermod -aG docker ec2-user

Then, reconnect to apply changes.

For Ubuntu:

sudo apt update -y
sudo apt install docker.io -y
sudo systemctl start docker
sudo systemctl enable docker
sudo usermod -aG docker ubuntu

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Step 3: Install Python and Flask

If your EC2 instance does not have Python installed:

sudo yum install python3 -y  # Amazon Linux
sudo apt install python3 -y  # Ubuntu

Then, install Flask:

pip3 install flask

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Step 4: Clone the Repository from GitHub

On your EC2 instance, clone the repository:

git clone https://github.com/your-github-username/FlaskCalculator.git
cd FlaskCalculator

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Step 5: Create the Dockerfile

Inside your FlaskCalculator directory, create a file named Dockerfile:

nano Dockerfile

Paste the following content:

# Use an official Python runtime as the base image
FROM python:3.9-slim

# Set the working directory inside the container
WORKDIR /app

# Copy application files to the container
COPY . /app

# Install dependencies
RUN pip install --no-cache-dir flask

# Expose the application port
EXPOSE 5000

# Command to run the application
CMD ["python", "app.py"]

Save and exit (CTRL + X, then Y, then Enter).

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Step 6: Build and Run the Docker Container

1. Build the Docker Image

docker build -t flask-calculator .

2. Run the Container

docker run -d -p 5000:5000 flask-calculator

3. Verify the Running Container

docker ps

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Step 7: Access Flask App

• Open a browser and visit:

  http://your-ec2-ip:5000
  

• If it's not accessible, update your EC2 security group:
  • Allow port 5000 for 0.0.0.0/0 (for testing, restrict later).

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Step 8: Push Image to Docker Hub

1. Login to Docker Hub

docker login

Enter your Docker Hub username and password.

2. Tag the Image

Replace your-docker-username with your actual Docker Hub username.

docker tag flask-calculator your-docker-username/flask-calculator

3. Push the Image

docker push your-docker-username/flask-calculator

Your image is now publicly available on Docker Hub!

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Step 9: Pull & Run the Image on Another Machine (Optional)

To run the container on another machine or EC2 instance:

docker pull your-docker-username/flask-calculator
docker run -d -p 5000:5000 your-docker-username/flask-calculator

Now, your app is running from Docker Hub! 🚀

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