Whether you're building microservices or deploying modern applications at scale, Docker and Amazon ECS (Elastic Container Service) are tools you’ll want in your DevOps toolbox. This guide will help you understand both — from container basics to orchestration.
🐳 What is Docker?
Docker is a platform used to package and deploy applications into containers — standardized, lightweight, and portable units.
A container includes
- Application code
- Dependencies (libraries, runtimes, etc.)
- OS libraries & environment
✅ Benefits of using containers
- Isolated from other containers
- Independently deployable
- Easily scalable
Docker is especially powerful in microservice architectures, as it enables clean decoupling of services.
📦 Docker Images & Dockerfile
- Docker images are blueprints of containers.
- Docker containers are running instances of those images.
🛠️ Images are created from a Dockerfile
A Dockerfile contains step-by-step instructions to build your image.
With Docker, you can:
- Run containers locally for testing
- Push images to repositories (like DockerHub or Amazon ECR)
- Deploy the same image across environments (dev, staging, prod)
🏗️ What is Amazon ECS?
Amazon Elastic Container Service (ECS) is a fully-managed container orchestration platform by AWS. It natively supports Docker and integrates deeply with AWS services.
You can run containers using two launch types
- EC2 (you manage the servers)
- Fargate (serverless — AWS manages it)
📄 ECS Task Definition
A Task Definition is a JSON file that defines how containers should run.
It includes:
- Docker image
- Port mappings
- CPU & memory
- IAM role
- Logging configuration
You can define up to 10 containers per task, but use multiple containers only if tightly coupled.
🔁 Running ECS Tasks
You can run tasks in multiple ways:
➤ Standalone Tasks
- Manually run using AWS CLI or Console
- Stops when complete or failed
➤ Scheduled Tasks
- Triggered by Amazon EventBridge
- Run at intervals or in response to events
⚙️ ECS Services
An ECS Service maintains a desired number of running tasks.
Features:
- Auto-replace failed tasks
- Auto-scaling via Application Auto Scaling
- Supports Application Load Balancer (ALB) for traffic routing
📌 ECS Clusters
An ECS Cluster is a logical grouping of:
- Tasks
- Services
- Infrastructure (EC2 or Fargate)
Clusters are scoped per AWS Region.
🖥️ EC2 Launch Type
With EC2, you provision your own servers to run containers.
Each EC2 instance must run
- ECS Agent
- Docker Engine
AWS provides ECS-Optimized AMIs to simplify setup.
🛠️ You are responsible for
- Scaling EC2 instances
- Patching & security
- Monitoring and updates
☁️ AWS Fargate Launch Type
Fargate is AWS’s serverless option to run containers without managing any infrastructure.
AWS handles
- Underlying compute
- Security
- Reliability
- Scaling
You only manage
- Your containerized application
- Task definitions and services
📊 Capacity Providers (CP)
A Capacity Provider determines where ECS runs your tasks.
🔹 Fargate Capacity Providers
- FARGATE: Default option
- FARGATE_SPOT: Up to 70% cheaper, but tasks may be interrupted
🔹 EC2 Capacity Providers
- Linked to EC2 Auto Scaling Groups
- ECS can automatically scale EC2 capacity
You can create a strategy that mixes multiple providers for
- ECS Services
- Standalone Tasks
✅ Final Thoughts
If you're starting with containers or looking to scale your cloud-native apps, Docker + ECS is a powerful combo. Fargate lets you forget about servers. EC2 gives you full control. And together, they let you focus on what matters most — building great applications.
✍️ Have questions or tips about running ECS in production? Drop them in the comments!
Top comments (2)
That was great, I almost didn't know about most of them.😍💪🏻
ECS too most widely used containerization technology!