Enforcing Image Immutability in ECR Using Repository Policy

Introduction

In this solution, we will enforce image immutability in Amazon Elastic Container Registry (ECR) using a repository policy. Image immutability ensures that once an image is pushed to the repository, it cannot be overwritten or deleted, providing a higher level of security and consistency for your containerized applications. The key services involved in this solution are Amazon ECR and Pulumi.

Step-by-Step Explanation

Step 1: Create an ECR Repository

First, we will create an ECR repository using Pulumi. This repository will store our container images.

Step 2: Define the Repository Policy

Next, we will define a repository policy that enforces image immutability. This policy will prevent any image tag from being overwritten or deleted once it is pushed to the repository.

Step 3: Apply the Repository Policy

Finally, we will apply the repository policy to the ECR repository using Pulumi. This will ensure that the policy is enforced and image immutability is maintained.

Key Points

• Amazon ECR: A fully managed container registry that makes it easy to store, manage, and deploy Docker container images.
• Image Immutability: Ensures that once an image is pushed to the repository, it cannot be overwritten or deleted.
• Pulumi: An infrastructure as code tool that allows you to define and manage cloud resources using programming languages like TypeScript.

Conclusion

By following this solution, you can enforce image immutability in your ECR repositories, providing a higher level of security and consistency for your containerized applications. Using Pulumi to define and manage the repository policy makes the process more efficient and maintainable.

Full Code Example

import * as pulumi from "@pulumi/pulumi";
import * as aws from "@pulumi/aws";

// Create an ECR repository
const ecrRepository = new aws.ecr.Repository("my-ecr-repo", {
    imageTagMutability: "IMMUTABLE", // Enforce image immutability
});

// Define the repository policy
const repositoryPolicy = new aws.ecr.RepositoryPolicy("my-ecr-repo-policy", {
    repository: ecrRepository.name,
    policy: pulumi.output(ecrRepository.arn).apply(arn => JSON.stringify({
        Version: "2012-10-17",
        Statement: [
            {
                Effect: "Allow",
                Principal: "*",
                Action: [
                    "ecr:BatchCheckLayerAvailability",
                    "ecr:BatchGetImage",
                    "ecr:DescribeImages",
                    "ecr:GetDownloadUrlForLayer"
                ],
                Resource: arn
            }
        ]
    }))
});

// Export the repository URL
export const repositoryUrl = ecrRepository.repositoryUrl;