How to Deploy a Containerized Application on AWS ECS Step by Step?

Introduction

In modern cloud-native development, deploying applications using containers has become a standard practice. Tools like Docker make it easy to package applications, and cloud platforms like AWS provide powerful services to run them.

One of the most popular services for running containers on AWS is Amazon Elastic Container Service (ECS).

In this article, we will learn how to deploy a containerized application on AWS ECS step by step, in simple words, with a real-world approach. This guide is perfect for beginners as well as developers preparing for cloud and DevOps interviews.

What is AWS ECS?

Amazon ECS (Elastic Container Service) is a fully managed container orchestration service.

👉 It helps you:

Run Docker containers in the cloud
Manage scaling and availability
Deploy applications easily

Why Use AWS ECS for Container Deployment?

1. Fully Managed Service

You don’t need to manage servers manually.

👉 AWS handles infrastructure, scaling, and availability.

2. Easy Integration with AWS Services

ECS works seamlessly with:

ECR (Elastic Container Registry)
IAM (Security)
CloudWatch (Monitoring)

3. Cost-Effective Deployment

You only pay for the resources you use.

4. Supports Fargate and EC2

Fargate → Serverless containers
EC2 → More control over infrastructure

Prerequisites Before Deployment

Before starting, make sure you have:

AWS Account
Docker installed
Basic knowledge of containers
Sample application (Node.js / .NET / Python)

Step-by-Step: Deploy Containerized Application on AWS ECS

Let’s go step by step.

Step 1: Create a Sample Application

You can use any application. Example: simple ASP.NET Core API.

app.MapGet("/", () => "Hello from ECS!");

👉 This will be our test application.

Step 2: Create a Dockerfile

A Dockerfile is used to build a container image.

FROM mcr.microsoft.com/dotnet/aspnet:8.0
WORKDIR /app
COPY . .
ENTRYPOINT ["dotnet", "YourApp.dll"]

👉 This defines how your app runs inside a container.

Step 3: Build Docker Image

Run the following command:

docker build -t myapp .

👉 This creates a Docker image locally.

Step 4: Create Amazon ECR Repository

Go to AWS Console → ECR → Create repository

👉 Example name: myapp-repo

Step 5: Push Image to ECR

aws ecr get-login-password --region your-region | docker login --username AWS --password-stdin your-account-id.dkr.ecr.region.amazonaws.com

Tag image:

docker tag myapp:latest your-ecr-url/myapp:latest

Push image:

docker push your-ecr-url/myapp:latest

👉 Now your image is stored in AWS.

Step 6: Create ECS Cluster

Go to ECS → Create Cluster

Choose:

Fargate (recommended for beginners)

👉 Give cluster name and create.

Step 7: Create Task Definition

Task Definition defines how your container runs.

Steps:

Choose Fargate
Add container
Provide image URL (from ECR)
Set CPU and memory
Configure port mapping (e.g., 80)

👉 This acts like a blueprint for your app.

Step 8: Create Service

Service keeps your application running.

Steps:

Select cluster
Choose task definition
Set number of tasks (e.g., 1)
Configure networking (VPC, subnets)

👉 Service ensures high availability.

Step 9: Configure Load Balancer (Optional but Recommended)

Use Application Load Balancer (ALB):

Distributes traffic
Provides public access

👉 Map ALB to your ECS service.

Step 10: Run and Access Application

After deployment:

Get public URL from Load Balancer
Open in browser

👉 You should see:

Hello from ECS!

Understanding ECS Components

1. Cluster

Logical group of resources.

2. Task Definition

Blueprint of container.

3. Task

Running instance of container.

4. Service

Maintains desired number of tasks.

Best Practices for AWS ECS Deployment

1. Use Fargate for Simplicity

No server management required.

2. Store Images in ECR

Secure and integrated with AWS.

3. Use Environment Variables

Avoid hardcoding configuration.

4. Enable Logging with CloudWatch

Track application logs easily.

5. Use Auto Scaling

Scale application based on traffic.

Common Mistakes to Avoid

❌ Not configuring security groups properly
❌ Using wrong image URL
❌ Ignoring logs
❌ Not exposing correct ports

Real-World Use Case

In production systems, ECS is used for:

Microservices deployment
API hosting
Background jobs

👉 Many companies use ECS for scalable cloud applications.

Summary

Deploying a containerized application on AWS ECS is a powerful way to run scalable and reliable applications in the cloud. By using Docker, ECR, and ECS together, you can easily build, store, and deploy your applications. Following best practices like using Fargate, enabling logging, and configuring load balancers ensures that your application is production-ready and performs efficiently.