Running Flask + MySQL with Docker Compose

Flask + MySQL with Docker Compose

This guide shows how to set up a Flask application with MySQL database using Docker Compose.

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1. Project Structure

flask-mysql-app/
│── docker-compose.yml
│── flask-app/
│   ├── Dockerfile
│   ├── requirements.txt
│   ├── app.py

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2. docker-compose.yml

version: "3.9"

services:
  flask-web:
    build: ./flask-app
    container_name: flask-web
    ports:
      - "5000:5000"
    environment:
      - DB_HOST=mysql-db
      - DB_USER=root
      - DB_PASSWORD=rootpassword
      - DB_NAME=testdb
    depends_on:
      - mysql-db
    networks:
      - app-network

  mysql-db:
    image: mysql:8.0
    container_name: mysql-db
    restart: always
    environment:
      MYSQL_ROOT_PASSWORD: rootpassword
      MYSQL_DATABASE: testdb
    ports:
      - "3306:3306"
    volumes:
      - mysql_data:/var/lib/mysql
    networks:
      - app-network

volumes:
  mysql_data:

networks:
  app-network:
    driver: bridge

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3. flask-app/Dockerfile

# Use official Python image
FROM python:3.11-slim

# Set working directory
WORKDIR /app

# Install dependencies
COPY requirements.txt .
RUN pip install --no-cache-dir -r requirements.txt

# Copy app code
COPY . .

# Expose port 5000
EXPOSE 5000

# Run the application
CMD ["python", "app.py"]

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4. flask-app/requirements.txt

flask
mysql-connector-python

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5. flask-app/app.py

from flask import Flask, jsonify
import mysql.connector
import os

app = Flask(__name__)

# Read DB configs from environment variables
db_config = {
    'host': os.getenv("DB_HOST", "localhost"),
    'user': os.getenv("DB_USER", "root"),
    'password': os.getenv("DB_PASSWORD", "rootpassword"),
    'database': os.getenv("DB_NAME", "testdb")
}

@app.route('/')
def hello_world():
    return "Hello from Flask + MySQL in Docker!"

@app.route('/users')
def get_users():
    try:
        conn = mysql.connector.connect(**db_config)
        cursor = conn.cursor()
        cursor.execute("CREATE TABLE IF NOT EXISTS users (id INT AUTO_INCREMENT PRIMARY KEY, name VARCHAR(50))")
        cursor.execute("INSERT INTO users (name) VALUES ('Santosh'), ('Amit'), ('Priya')")
        conn.commit()
        cursor.execute("SELECT * FROM users")
        result = cursor.fetchall()
        cursor.close()
        conn.close()
        return jsonify(result)
    except Exception as e:
        return jsonify({"error": str(e)})

if __name__ == "__main__":
    app.run(host="0.0.0.0", port=5000)

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6. Run the Setup

Build and start services:

docker-compose up --build

Access Flask app:

• Open: http://localhost:5000 → "Hello from Flask + MySQL in Docker!"
• Open: http://localhost:5000/users → returns user list from MySQL DB.

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👉 This setup proves portability:

• You can run it on any system with Docker & Docker Compose.
• It ships Flask + MySQL together, fully isolated in containers.
• No manual installation of Python/MySQL needed.