Docker Blog

Designing for Containerization

Understanding how to refactor monolithic applications into microservices-based architectures for efficient containerization.

By Docker Engineering Team

Published August 30, 2025

Containerization has changed how we design applications. This guide explores architectural considerations for building container-native applications, with practical examples and best practices.

Key Architecture Principles

Single Responsibility

Each container should handle one task or service

Statelessness

Design containers to minimize persistent state needs

1. Service Decomposition

Break monolithic applications into microservices. Use domain-driven design to identify natural service boundaries.


// Example: Service boundaries
Authentication Service
    - User management
    - Token generation
Payments Service
    - Credit card processing
    - Payment history

2. Container Networking Best Practices

Create logical service networks to enable communication between containers while maintaining isolation.


# Create overlay network
docker network create service-api

# Run services on the network
docker run --name user-service --network service-api ...
docker run --name payment-service --network service-api ...

3. Configuration Patterns

Use environment variables and Docker secrets to manage configuration instead of baking values into images.

Example docker-compose.yml

services: web: image: my-web-app environment: PORT: 8080 DB_HOST: db-service secrets: - api_key secrets: api_key: file: ./secrets/api-key.txt

4. Horizontal Scaling

Design services for horizontal scaling. Use stateless architecture patterns and load balancing for scalability.

Use Kubernetes deployments with horizontal pod autoscaling or Docker Swarm services with scale features.

Conclusion

Containerization requires rethinking application architecture. By following these principles, you can build scalable, maintainable systems that leverage container advantages.

Ready to Optimize?

Start by containerizing a single service and gradually refactor legacy applications.

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