Efficient Docker Image Management in Amazon ECR with Lifecycle Policies

Introduction

Container image management is a foundational element of modern DevOps and cloud-native infrastructure. Maintaining clean, cost-effective, and manageable image repositories becomes critical as organizations scale their CI/CD pipelines and deploy across multiple environments.

Amazon Elastic Container Registry (ECR) offers lifecycle policies as a powerful mechanism to automate image retention and cleanup.

This blog offers insights and best practices for leveraging Amazon ECR lifecycle policies to optimize your container image management strategy.

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Objective

When managing Docker images in Amazon ECR, organizations should prioritize the following objectives:

Cost Optimization: Minimize storage expenses by automatically removing outdated or unused images.
Operational Clarity: Reduce repository clutter and ensure developers can easily identify relevant images.
Risk Mitigation: Retain sufficient image versions for reliable rollback and deployment continuity.
Automation: Eliminate manual cleanup efforts and reduce human error.

Why Implement Amazon ECR Lifecycle Policies?

In most CI/CD pipelines, container images are built and pushed frequently. Without cleanup mechanisms, repositories can grow rapidly, introducing several challenges:

Storage Bloat: Hundreds of old images, especially from automated builds.
Cost Overruns: Amazon ECR charges for storage and outdated images increase your bill.
Operational Confusion: Developers may not know which image is the latest or safe.

Implementing lifecycle policies is a best practice for organizations seeking to maintain efficient, scalable, and cost-effective container image management.

Best Practices for Amazon ECR Lifecycle Policy Design

Below are recommended best practices for designing and implementing Amazon ECR lifecycle policies:

Automate Cleanup of Untagged Images

Recommendation: Configure policies to automatically expire untagged images after a set period (e.g., 30 days).

Rationale: Untagged images are artifacts of failed or intermediary builds and are rarely needed after a short period. Automating their removal prevents unnecessary storage consumption and keeps repositories clean.

Retain Key Tagged Images by Environment

Recommendation: Implement separate rules for each environment (e.g., prod-, uat-, dev-) to retain a minimum number of recent, stable images. (Note: The tag prefixes (such as prod-, uat-, dev-) used in the examples may differ in your case. Please adjust the rules to match your organization’s tagging conventions.)

Rationale: Maintaining several tagged images per environment ensures you have reliable rollback options and protects against accidental deletion of critical versions.

Separate rules are applied for each environment prefix (prod-, uat-, dev-) to ensure we always have a few recent versions available.

Set Global Retention Window

Recommendation: Establish a fallback rule to retain all images younger than a specified age (e.g., 90 days), regardless of tag status.

Rationale: This acts as a safety net, covering edge cases or one-off builds that environment-specific rules might not capture.

Implementation Approach

You can easily apply this policy in the AWS Management Console or the AWS CLI. Here’s the step-by-step console approach:

Console Steps:

Go to Amazon ECR Console
Select the desired repository
Click on “Lifecycle Policy” in the left panel
Click “Edit lifecycle policy”
Paste the JSON content (provided below)
Click “Save”

Full JSON Policy:

{
  "rules": [
    {
      "rulePriority": 1,
      "description": "Remove untagged images - 30 days old",
      "selection": {
        "tagStatus": "untagged",
        "countType": "sinceImagePushed",
        "countUnit": "days",
        "countNumber": 30
      },
      "action": { "type": "expire" }
    },
    {
      "rulePriority": 2,
      "description": "Retain at least 3 images and images younger than 90 days for prod",
      "selection": {
        "tagStatus": "tagged",
        "tagPrefixList": ["prod-"],
        "countType": "imageCountMoreThan",
        "countNumber": 3
      },
      "action": { "type": "expire" }
    },
    {
      "rulePriority": 3,
      "description": "Retain at least 3 images and images younger than 90 days for uat",
      "selection": {
        "tagStatus": "tagged",
        "tagPrefixList": ["uat-"],
        "countType": "imageCountMoreThan",
        "countNumber": 3
      },
      "action": { "type": "expire" }
    },
    {
      "rulePriority": 4,
      "description": "Retain at least 3 images and images younger than 90 days for dev",
      "selection": {
        "tagStatus": "tagged",
        "tagPrefixList": ["dev-"],
        "countType": "imageCountMoreThan",
        "countNumber": 3
      },
      "action": { "type": "expire" }
    },
    {
      "rulePriority": 5,
      "description": "Retain images less than 90 days old",
      "selection": {
        "tagStatus": "any",
        "countType": "imageCountMoreThan",
        "countNumber": 1
      },
      "action": { "type": "expire" }
    }
  ]
}

{

"rules": [

{

"rulePriority": 1,

"description": "Remove untagged images - 30 days old",

"selection": {

"tagStatus": "untagged",

"countType": "sinceImagePushed",

"countUnit": "days",

"countNumber": 30

"action": { "type": "expire" }

{

"rulePriority": 2,

"description": "Retain at least 3 images and images younger than 90 days for prod",

"selection": {

"tagStatus": "tagged",

"tagPrefixList": ["prod-"],

"countType": "imageCountMoreThan",

"countNumber": 3

"action": { "type": "expire" }

{

"rulePriority": 3,

"description": "Retain at least 3 images and images younger than 90 days for uat",

"selection": {

"tagStatus": "tagged",

"tagPrefixList": ["uat-"],

"countType": "imageCountMoreThan",

"countNumber": 3

"action": { "type": "expire" }

{

"rulePriority": 4,

"description": "Retain at least 3 images and images younger than 90 days for dev",

"selection": {

"tagStatus": "tagged",

"tagPrefixList": ["dev-"],

"countType": "imageCountMoreThan",

"countNumber": 3

"action": { "type": "expire" }

{

"rulePriority": 5,

"description": "Retain images less than 90 days old",

"selection": {

"tagStatus": "any",

"countType": "imageCountMoreThan",

"countNumber": 1

"action": { "type": "expire" }

}

]

}

Final Thoughts

Implementing Amazon ECR lifecycle policies is a best practice for long-term container image management. This setup:

Automates cleanup of stale, untagged images
Ensures reliable rollback options by retaining key tagged builds
Helps control costs by managing image sprawl
Makes your DevOps pipelines more maintainable and future-proof

Customize these rules for your team’s tagging conventions and retention requirements. A little configuration now can save you hours of cleanup and dollars down the road.

Drop a query if you have any questions regarding Amazon ECR and we will get back to you quickly.

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FAQs

1. What is an Amazon ECR Lifecycle Policy?

ANS: – An Amazon ECR (Elastic Container Registry) lifecycle policy is a set of automated rules that help manage the lifecycle of Docker images in your repository. It allows you to automatically remove old or unneeded images based on conditions like tag status, image age, or image count.

2. Why do we need a lifecycle policy for Amazon ECR repositories?

ANS: – Without a lifecycle policy, your Amazon ECR repository may accumulate hundreds or thousands of images over time, leading to: