Deploying Flask/Django Apps

Deploying a web application involves making it accessible to users over the internet. Flask and Django apps can be deployed on various platforms, including Heroku, AWS, DigitalOcean, and PythonAnywhere. This guide covers step-by-step deployment for both Flask and Django.

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1. Deployment Preparation

Before deploying, ensure:

Your application runs locally without errors
You have a requirements.txt file listing dependencies
You use a virtual environment to manage dependencies
You have configured environment variables correctly

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2. Deployment of Flask Apps

Flask applications can be deployed using Gunicorn (for running production servers) and Nginx or Apache (for reverse proxy).

2.1 Creating a Flask App

from flask import Flask

app = Flask(__name__)

@app.route("/")
def home():
    return "Hello, Flask Deployment!"

if __name__ == "__main__":
    app.run(debug=True)

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2.2 Install Dependencies

Create a virtual environment and install dependencies:

python -m venv venv
source venv/bin/activate  # On Windows, use venv\Scripts\activate
pip install flask gunicorn

Freeze dependencies into a requirements.txt file:

pip freeze > requirements.txt

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2.3 Deploy Flask App on Heroku

Step 1: Install Heroku CLI

Download and install Heroku CLI from Heroku Official Site.

Step 2: Login to Heroku

heroku login

Step 3: Create a Procfile

Heroku needs a Procfile to define the entry point:

web: gunicorn app:app

Step 4: Initialize Git and Deploy

git init
heroku create flask-app-name
git add .
git commit -m "Initial commit"
git push heroku main

Step 5: Open the App

heroku open

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2.4 Deploy Flask App on AWS EC2

1. Launch an EC2 instance (Ubuntu)
2. Install Python, Flask, and Gunicorn: sudo apt update && sudo apt install python3-pip pip install flask gunicorn
3. Run the Flask App: gunicorn --bind 0.0.0.0:8000 app:app
4. Use Nginx as a Reverse Proxy (Optional for production).

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3. Deployment of Django Apps

Django apps require Gunicorn and Nginx for production deployment.

3.1 Creating a Django App

Install Django and create a project:

pip install django gunicorn
django-admin startproject myproject
cd myproject

Run migrations:

python manage.py migrate

Run the server:

python manage.py runserver

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3.2 Deploy Django on Heroku

Step 1: Install Heroku CLI

pip install django-heroku gunicorn

Step 2: Modify settings.py

Add:

import django_heroku
django_heroku.settings(locals())

Step 3: Create Procfile

web: gunicorn myproject.wsgi

Step 4: Initialize Git and Deploy

git init
heroku create django-app-name
git add .
git commit -m "Initial commit"
git push heroku main

Step 5: Open the App

bashCopyEditheroku open

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3.3 Deploy Django on AWS EC2

1. Launch EC2 instance
2. Install dependencies: sudo apt update && sudo apt install python3-pip pip install django gunicorn
3. Run Gunicorn: gunicorn --bind 0.0.0.0:8000 myproject.wsgi
4. Configure Nginx as a Reverse Proxy.

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4. Using Docker for Deployment

Both Flask and Django apps can be deployed using Docker.

4.1 Create a Dockerfile

For Flask:

FROM python:3.9
WORKDIR /app
COPY . .
RUN pip install -r requirements.txt
CMD ["gunicorn", "-b", "0.0.0.0:8000", "app:app"]

For Django:

FROM python:3.9
WORKDIR /app
COPY . .
RUN pip install -r requirements.txt
CMD ["gunicorn", "-b", "0.0.0.0:8000", "myproject.wsgi"]

4.2 Build and Run the Docker Container

docker build -t myapp .
docker run -p 8000:8000 myapp