Implement Amazon Elastic Container Registry (ECR) lifecycle policies to automatically manage container image retention, optimize storage costs, and improve overall repository efficiency.
Why Lifecycle Policies Matter
Container image storage can quickly become a significant cloud expense. Without proper management, organizations can inadvertently accumulate unnecessary images that consume valuable storage and increase monthly costs. A well-designed ECR lifecycle policy helps:
- Automatically remove unused images
- Reduce storage costs
- Improve repository performance
- Maintain clean and manageable container registries
Potential Cost Impact
Consider this real-world scenario:
- Current Storage: 1TB of ECR images = $100/month
- After Lifecycle Policy: 100GB of images = $4/month
- Cost Reduction: 96% storage cost savings
How Lifecycle Policies Work
Lifecycle policies enable automatic image management by:
- Setting retention rules based on image age
- Defining maximum number of images to keep
- Automatically removing untagged or outdated images
- Preventing unnecessary image accumulation
Implementation Guide
Infrastructure as Code Example (Terraform)
resource "aws_ecr_lifecycle_policy" "example" {
repository = aws_ecr_repository.example.name
policy = jsonencode({
rules = [
{
rulePriority = 1
description = "Remove untagged images older than 30 days"
selection = {
tagStatus = "untagged"
countType = "sinceImagePushed"
countUnit = "days"
countNumber = 30
}
action = {
type = "expire"
}
}
]
})
}Manual Implementation Steps
- Navigate to Amazon ECR in AWS Console
- Select target repository
- Go to “Lifecycle Policy” tab
- Click “Edit”
- Configure retention rules
- Save policy
Best Practices
- Retain Recent Images: Keep last 10-20 images
- Set Reasonable Expiration: 30-90 days typical
- Tag Important Images: Prevent accidental deletion
- Monitor Initial Policy Deployment
Recommended Tools
- Infracost: Identifies and helps remediate ECR lifecycle policy gaps during infrastructure review
- AWS CLI: Script and automate lifecycle policy management
- Terraform: Infrastructure as code implementation
Example Scenarios
Scenario 1: Development Environment
- Problem: Developers generate multiple images daily
- Solution: Implement 7-day untagged image expiration
- Result: 70% storage reduction
Scenario 2: Production Pipeline
- Problem: Accumulated historical images consuming storage
- Solution: 90-day retention policy
- Result: Consistent, managed repository
Considerations and Caveats
- Careful Configuration: Prevent accidental image deletion
- CI/CD Impact: Ensure policies don’t interrupt build processes
- Compliance Requirements: Some industries need longer retention
- Performance Overhead: Minimal computational impact