multi-region

Multi-Region ECR Repository Example

This example demonstrates two approaches for creating ECR repositories across multiple AWS regions for disaster recovery and global distribution use cases:

1. Built-in Replication (Recommended) - Uses the module's new replication features for automatic cross-region replication
2. Manual Setup (Alternative) - Manually creates repositories in each region with custom replication configuration

Architecture

Built-in Replication Approach (Recommended)

┌─────────────────┐     ┌──────────────────────┐
│                 │     │  Primary Region      │
│  CI/CD System   │────▶│  ┌───────────────┐   │
│  (Image Builds) │     │  │ ECR Repository│   │
│                 │     │  │  + Replication│   │
│                 │     │  └───────────────┘   │
└─────────────────┘     └──────────┬───────────┘
                                   │
                                   │ Automatic Replication
                                   │ (Managed by AWS)
                                   ▼
┌─────────────────────┐
│  Secondary Region   │
│  ┌───────────────┐  │
│  │ ECR Repository│  │
│  │   (Replica)   │  │
│  └───────────────┘  │
└─────────────────────┘

Manual Setup Approach (Alternative)

┌─────────────────┐     ┌──────────────────────┐
│                 │     │  Primary Region      │
│  CI/CD System   │────▶│  ┌───────────────┐   │
│  (Image Builds) │     │  │ ECR Repository│   │
│                 │     │  └───────────────┘   │
└─────────────────┘     └──────────┬───────────┘
                                   │
                                   │ Manual Replication Config
                                   ▼
┌─────────────────────┐
│  Secondary Region   │
│  ┌───────────────┐  │
│  │ ECR Repository│  │
│  │   (Manual)    │  │
│  └───────────────┘  │
└─────────────────────┘

Use Cases

1. Disaster Recovery - Ensure container images are available even if a region becomes unavailable
2. Global Deployments - Deploy containers from region-local repositories to reduce latency
3. Cross-Region Redundancy - Support multi-region application architectures
4. Edge Deployments - Support edge computing scenarios with region-specific image repositories

What This Example Creates

1. An ECR repository in the primary region
2. An ECR repository in the secondary region
3. ECR replication configuration to copy images automatically

Prerequisites

• AWS account with permissions to create ECR resources in multiple regions
• Terraform 1.3.0+
• AWS provider 5.0.0+

Usage

terraform init
terraform apply

After applying this Terraform code:

1. Push images to the primary region's repository
2. Images will automatically replicate to the secondary region
3. Your applications can pull from the geographically closest repository

Pushing an Image

# Login to ECR in primary region
aws ecr get-login-password --region us-east-1 | docker login --username AWS --password-stdin <account-id>.dkr.ecr.us-east-1.amazonaws.com

# Build and tag your image
docker build -t multi-region-app:v1.0.0 .
docker tag multi-region-app:v1.0.0 <account-id>.dkr.ecr.us-east-1.amazonaws.com/multi-region-app:v1.0.0

# Push to primary region
docker push <account-id>.dkr.ecr.us-east-1.amazonaws.com/multi-region-app:v1.0.0

# The image will automatically replicate to the secondary region
# You can pull from the secondary region after replication completes:
aws ecr get-login-password --region us-west-2 | docker login --username AWS --password-stdin <account-id>.dkr.ecr.us-west-2.amazonaws.com
docker pull <account-id>.dkr.ecr.us-west-2.amazonaws.com/multi-region-app:v1.0.0

Monitoring Replication

You can monitor the replication status using AWS CLI:

aws ecr describe-images --repository-name multi-region-app --region us-east-1
aws ecr describe-images --repository-name multi-region-app --region us-west-2

Best Practices

1. Push to Primary Only - Always push images to the primary region and let AWS handle replication
2. Immutable Tags - Use immutable tags to ensure consistency across regions
3. Version Images - Use semantic versioning in image tags (v1.0.0) rather than mutable tags like 'latest'
4. Regional Endpoints - Configure applications to pull from their regional ECR endpoint

Clean Up

To destroy all resources created by this example:

terraform destroy

Note: You must delete all images from the repositories before they can be deleted, or set force_delete = true in the module configuration.