ECR – Elastic Container Registry and ECS -Elastic Container Service

Back ECR – Elastic Container Registry and ECS -Elastic Container Service 04 Nov, 2025

ABHISHEK AGNIHOTRI

🌊 ECR – Elastic Container Registry

🧱 Think of ECR as your “Private Container Warehouse.”

Whenever you build a Docker Image, it needs a place to live before deployment —
👉 That’s where ECR comes in!

🎨 ECR Explained Visually:

📦 Docker Image → 🚚 Pushed to ECR (Storage) → 🚀 Pulled by ECS for Deployment

🧩 Key Features of ECR:

💡 Feature	🌈 Description
🏠 Image Storage	Stores Docker images securely in AWS Cloud.
🔒 Private or Public	You can keep your images private (for internal apps) or public.
⚡ Integration with ECS & EKS	Works seamlessly with ECS (Containers) or EKS (Kubernetes).
🧰 Version Control	Maintains different versions of your images.
🧼 Automated Cleanup	Can automatically delete old, unused images.

🧠 Example:

When you build your app:

docker build -t myapp .

You tag it:

docker tag myapp:latest <aws_account_id>.dkr.ecr.us-east-1.amazonaws.com/myapp:latest

Then push it to ECR:

docker push <aws_account_id>.dkr.ecr.us-east-1.amazonaws.com/myapp:latest

Now your image is safely stored in ECR, ready to be deployed 🚀

🛳️ ECS – Elastic Container Service

ECS is like a Captain that runs and manages your containers across servers ⛴️

🎨 ECS Explained Visually:

🧱 Docker Image (from ECR) → 🧠 ECS Task Definition → ⚙️ ECS Service → 🖥️ Running Containers on EC2 or Fargate

🧩 Key Concepts in ECS:

💡 Concept	🌈 Description
🧱 Task Definition	A blueprint — tells ECS what image to run, CPU/RAM needed, ports, and environment variables.
⚙️ Service	Ensures a specific number of containers (tasks) are always running.
🖥️ Cluster	A logical group of servers (EC2 instances or Fargate).
☁️ Launch Types	Two ways to run containers: • EC2 – You manage servers.• Fargate – AWS manages servers (serverless).
🌐 Load Balancer	Distributes traffic evenly to all running containers.

🧠 Simple Example Flow:

You store your Docker image in ECR 🏠
You create a Task Definition in ECS ⚙️
ECS pulls the image from ECR 📦
ECS runs your container on Fargate or EC2 🚀
A Load Balancer directs user traffic to it 🌍

🔄 How ECR & ECS Work Together

Step	Process	Description
1️⃣	🧱 Build Image	Create Docker image locally or via CI/CD.
2️⃣	☁️ Push to ECR	Upload the image to AWS ECR.
3️⃣	⚙️ Configure ECS	Create a task definition that refers to your ECR image.
4️⃣	🚀 Run Service	ECS launches containers using that image.
5️⃣	🔁 Auto Scaling	ECS scales containers up/down based on demand.

💬 In One Line:

🧱 ECR stores your Docker images,
🛳️ ECS runs your Docker containers — easily, securely, and at scale.

🌟 Analogy:

Real Life	AWS
🏭 Factory Warehouse	🧱 ECR (stores your products/images)
🚚 Factory Machines Running	🛳️ ECS (runs your production/containers)

🚀 Quick Visual Summary

[ Developer ]
     👇
[ Docker Build ]
     👇
[ Push to ECR 🧱 ]
     👇
[ ECS pulls image 🛳️ ]
     👇
[ Runs container 🚀 ]
     👇
[ Users Access via Load Balancer 🌐 ]