Amazon ECR
What is it?
Amazon ECR is AWS's managed registry for storing, versioning, and distributing container images.
Explain like I'm 5
Why was it created?
Container deployments need a place to store and serve images. ECR was created as a secure, managed image registry integrated with AWS.
Where is it used?
- Storing container images
- Feeding ECS and EKS deployments
- CI/CD image publishing
- Versioning container builds
Why should developers care?
If you run containers on AWS (ECS, EKS), you'll store their images in ECR, so it's a routine part of container workflows.
How does it work?
You build a container image and push it to an ECR repository, where it's stored and versioned by tags. AWS services like ECS and EKS pull images from ECR to run them, with access controlled by IAM and images optionally scanned for vulnerabilities.
Real-world example
A CI pipeline builds an image, pushes it to ECR tagged with the version, and ECS pulls that exact image to deploy.
Common use cases
- Hosting private container images
- Supplying ECS/EKS deployments
- Versioning images by tag
- Vulnerability scanning of images
Advantages
- Managed and secure registry
- Tight ECS/EKS integration
- IAM-controlled access
- Optional image scanning
Disadvantages
- AWS-specific
- Storage costs
- Another piece in the workflow
- Best within AWS ecosystem
When should you use it?
When running containers on AWS and needing a private, integrated place to store images.
When should you avoid it?
If you're standardized on another registry or not using containers on AWS.
Alternatives
Related terms
Interview questions
Beginner
- What is Amazon ECR?
- What is a container image?
Intermediate
- How do ECS/EKS use ECR?
- How are images versioned in ECR?
Senior
- How do you secure and scan images in ECR?
- How does ECR fit into a CI/CD pipeline?
Common misconceptions
- "ECR runs your containers" — it stores images; ECS, EKS, or other runtimes actually run them.
- "ECR is public like Docker Hub" — it's a private, IAM-controlled registry by default.
Fun facts
- ECR stands for Elastic Container Registry.
- It can scan stored images for known vulnerabilities.
Timeline
- 2015 — Amazon ECR launches alongside ECS
Learning resources
Quick summary
Amazon ECR is AWS's managed, private container image registry that stores and versions images for ECS, EKS, and CI/CD to pull and run.
Cheat sheet
- Managed container registry
- Stores/versions images by tag
- Feeds ECS and EKS
- IAM-controlled, scannable