Deploying Containerized Apps to AWS with Docker and CI/CD

Deploying applications consistently across different environments is one of the biggest challenges in software development. Docker containers solve this by packaging your application with all its dependencies. Here's how I set up a complete CI/CD pipeline for AWS deployments.

The Docker Setup

Every project starts with a well-crafted Dockerfile. For Node.js applications, I use multi-stage builds to keep the final image small:

The first stage installs all dependencies and builds the application. The second stage only copies the built artifacts, resulting in images that are 80% smaller.

AWS Architecture

For most applications, I use the following AWS services:

• **ECS Fargate**: Serverless container orchestration
• **ECR**: Private container registry
• **Application Load Balancer**: Traffic distribution and SSL termination
• **RDS**: Managed PostgreSQL database
• **ElastiCache**: Redis for caching and sessions

CI/CD Pipeline

Using GitHub Actions, the pipeline runs on every push:

1. **Test**: Run unit and integration tests
2. **Build**: Create Docker image with git SHA as tag
3. **Push**: Upload to Amazon ECR
4. **Deploy**: Update ECS service with new image

Zero-Downtime Deployments

ECS rolling deployments ensure zero downtime. The new containers must pass health checks before old containers are terminated. I configure minimum healthy percent at 100% and maximum at 200% for smooth transitions.

Monitoring and Alerts

CloudWatch collects logs and metrics. I set up alarms for: - CPU and memory utilization above 80% - Error rate exceeding 1% - Response time above 500ms

This setup has served me well across multiple projects, handling everything from startups to enterprise applications.