In the world of modern software development, containerization has become a cornerstone of efficient deployment and scalability. Docker makes it easy to package applications and their dependencies into portable containers. In this blog, we’ll walk you through creating a multi-container PHP and MySQL application using Docker Compose.
Consistency: Run your app in the same environment across all stages of development and production.
Isolation: Keep services like PHP and MySQL in separate containers for modular and maintainable setups.
Ease of Scaling: Add or remove containers easily as the app grows.
Your project directory should look like this:
project/ │ ├── php-app/ │ ├── Dockerfile │ └── index.php │ └── docker-compose.yml
Here’s the docker-compose.yml file:
version: '3.8' services: php-app: build: ./php-app # Builds the PHP app Docker image from the ./php-app directory ports: - "8080:80" # Maps port 8080 on the host to port 80 in the container depends_on: - mysql # Ensures MySQL starts before the PHP app mysql: image: mysql:8.0 # Uses the official MySQL image ports: - "3306:3306" # Maps port 3306 on the host to port 3306 in the container environment: MYSQL_ROOT_PASSWORD: root # Root password for MySQL MYSQL_DATABASE: mydb # Initial database to create volumes: - mysql-data:/var/lib/mysql # Persists MySQL data in a named volume volumes: mysql-data: # Declares a named volume for MySQL data persistence
The index.php file connects to the MySQL container:
<?php $servername = "mysql"; // Service name defined in docker-compose.yml $username = "root"; $password = "root"; $database = "mydb"; try { // Create connection $conn = new PDO("mysql:host=$servername;dbname=$database", $username, $password); // Set PDO error mode to exception $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION); echo "Connected to MySQL successfully!"; } catch (PDOException $e) { echo "Connection failed: " . $e->getMessage(); } ?>
The Dockerfile builds the PHP container with required dependencies:
# Use the official PHP image FROM php:8.2-apache # Install PDO MySQL extension RUN docker-php-ext-install pdo pdo_mysql # Set the working directory WORKDIR /var/www/html # Copy the application code COPY index.php . # Expose port 80 EXPOSE 80
Create the Directory Structure
Build and Start the Containers Open a terminal in the project directory and run:
docker-compose up --build
Access the PHP Application Visit http://localhost:8080 in your browser. If everything is set up correctly, you should see:
Connected to MySQL successfully!
Use a MySQL client or MySQL Workbench.
Connect to localhost:3306 with:
Username: root
Password: root
Verify the database mydb is created.
Service Dependency Management: depends_on ensures MySQL starts before the PHP application.
Data Persistence: The mysql-data volume stores MySQL data, preventing loss across container restarts.
Port Mapping: Easily access services through ports mapped to the host machine.
Add more services like Nginx or Redis to the Compose file.
Use .env files to manage sensitive configurations.
Scale services using Docker Compose’s scale option for horizontal scaling.
With this setup, you've built a scalable, modular PHP and MySQL application using Docker Compose. Containerization simplifies environment management and prepares your app for cloud deployments. Whether you’re a beginner or a seasoned developer, Docker is an indispensable tool for modern application development.
Ready to take your setup to the next level? Try integrating this with CI/CD pipelines or Kubernetes for a production-grade environment.
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