Comparing Container Registries:
Docker Hub vs. GCR/Artifact Registry vs. ECR vs. ACR

Last updated: April 20, 2025

1. Introduction: What is a Container Registry?

A container registry is a centralized repository for storing, managing, and distributing container images (like Docker images). Think of it like GitHub, but for container images instead of source code. Registries allow developers and CI/CD systems to push new image versions and enable servers or orchestration platforms (like Kubernetes) to pull the correct image version for deployment.

While many registries exist (including self-hosted options like Harbor or Nexus), the most commonly used ones include the public Docker Hub and the managed private registries offered by major cloud providers: Google Cloud (GCR/Artifact Registry), Amazon Web Services (ECR), and Microsoft Azure (ACR). This article compares these four primary options.

2. Docker Hub

• Provider: Docker, Inc.
• Overview: The default public registry for Docker images and the largest library of container images. It serves as the central hub for many official open-source project images. It also offers private repositories.
• Key Features:
  • Massive public repository of official and community images.
  • Private repositories (limited number on free tier, more with paid plans).
  • Automated builds from GitHub/Bitbucket.
  • Webhooks for triggering actions on image push.
  • Basic vulnerability scanning on paid tiers.
  • Organizations and teams support.
  • Integrated with Docker Desktop.
• Pros: Default, easy to get started, huge selection of public images.
• Cons: Rate limits on image pulls for anonymous/free users can impact CI/CD, vulnerability scanning is basic/paid, less integrated with specific cloud provider workflows compared to their native offerings.
• Use Case: Public image distribution, individual developers, small teams, projects not tightly coupled to a specific cloud provider.

3. Google Container Registry (GCR) & Artifact Registry

• Provider: Google Cloud Platform (GCP).
• Overview: Google Cloud's managed container registry service. Note: Google Container Registry (GCR) is being superseded by Artifact Registry, which supports multiple artifact types (Docker images, Maven, npm, etc.) and offers more features. GCR will be shut down in early 2025, though existing gcr.io repositories can be hosted by Artifact Registry for compatibility. New projects should use Artifact Registry.
• Key Features (Artifact Registry):
  • Stores Docker images and other package formats (Maven, npm, Python, etc.).
  • Fine-grained access control using Google Cloud IAM.
  • Regional and multi-regional repository locations.
  • Vulnerability scanning (integrates with Google Cloud security services).
  • Supports gcr.io domain for GCR compatibility.
  • Integration with Cloud Build, GKE, Cloud Run.
  • Remote repositories (proxy/cache for Docker Hub, etc.).
  • Virtual repositories (aggregate multiple repositories).
• Pros: Excellent integration with GCP services, strong IAM controls, supports multiple artifact types, Artifact Registry offers more flexibility than GCR.
• Cons: Primarily focused on GCP users, pricing based on storage and network egress. GCR deprecation requires migration planning.
• Use Case: Organizations heavily invested in GCP, needing integrated artifact management beyond just containers.

4. Amazon Elastic Container Registry (ECR)

• Provider: Amazon Web Services (AWS).
• Overview: AWS's fully managed Docker container registry service. Designed for seamless integration within the AWS ecosystem.
• Key Features:
  • Deep integration with AWS services (ECS, EKS, Lambda, CodeBuild, etc.).
  • Fine-grained access control using AWS IAM policies.
  • Repositories are regional, but cross-region replication can be configured.
  • Image vulnerability scanning (integrates with Amazon Inspector).
  • Lifecycle policies for automatic image cleanup.
  • Immutable image tags option.
  • Encryption at rest (AWS managed or customer-managed keys).
  • Public registry option (ECR Public).
• Pros: Tight integration with AWS, robust security via IAM, mature service, public registry available.
• Cons: Primarily focused on AWS users, cross-region replication requires configuration, pricing based on storage and data transfer.
• Use Case: Organizations primarily using AWS for compute and orchestration.

5. Azure Container Registry (ACR)

• Provider: Microsoft Azure.
• Overview: Azure's managed OCI-compliant registry for storing container images and related artifacts (e.g., Helm charts).
• Key Features:
  • Integration with Azure services (AKS, App Service, Azure DevOps, etc.).
  • Authentication via Azure Active Directory (Azure AD) and role-based access control (RBAC).
  • Geo-replication for multi-region deployments and resilience.
  • ACR Tasks for automating image builds, testing, and patching within Azure.
  • Vulnerability scanning (integrates with Microsoft Defender for Cloud).
  • Content Trust support (Docker Content Trust / Notary v1).
  • Various service tiers (Basic, Standard, Premium) with different features/performance.
• Pros: Strong integration with Azure ecosystem, geo-replication is a key feature, ACR Tasks provides powerful build automation, tiered pricing.
• Cons: Primarily focused on Azure users, some advanced features tied to higher tiers.
• Use Case: Organizations primarily using Azure, needing integrated build/deployment automation or geo-replication.

6. Key Comparison Points

6.1 Cloud Provider Integration

ECR, ACR, and Artifact Registry offer deep integration with their respective cloud platforms (AWS, Azure, GCP) for identity management (IAM/RBAC/Azure AD), compute services (ECS/EKS, AKS, GKE/Cloud Run), and CI/CD tools (CodeBuild, Azure DevOps, Cloud Build). Docker Hub is cloud-agnostic but lacks this tight coupling.

6.2 Pricing Models

• Docker Hub: Generous free tier for public repos, limited free private repos. Paid tiers offer more private repos, concurrent builds, scanning, etc. Subject to pull rate limits on free/anonymous tiers.
• ECR/ACR/Artifact Registry: Generally follow cloud provider patterns - primarily based on storage consumed and network data transfer out. Often have small free storage tiers. Pricing can be complex depending on usage patterns (e.g., cross-region replication costs). ACR offers distinct performance/feature tiers.

6.3 Security Features

All cloud provider registries offer robust authentication/authorization integrated with their platform's IAM/RBAC systems. They also provide built-in vulnerability scanning (though capabilities and underlying scanners may differ). Docker Hub's scanning is primarily a paid feature. ACR supports Content Trust (Notary v1); ECR supports immutable tags.

6.4 Public vs. Private Repositories

Docker Hub is the primary destination for public images. ECR also offers ECR Public. ACR and Artifact Registry are primarily focused on private repositories within an organization, although Artifact Registry can be configured for public read access.

6.5 Other Features (Replication, Build Automation)

• Replication: ACR offers easy-to-configure geo-replication. ECR requires manual cross-region replication setup. Artifact Registry supports regional and multi-regional locations.
• Build Automation: ACR Tasks allows building images directly within Azure based on code commits or base image updates. Docker Hub has automated builds linked to code repositories. ECR and Artifact Registry rely on separate CI/CD services like CodeBuild or Cloud Build.

7. Comparison Summary Table

8. Choosing the Right Registry

• Default/Public Images: Docker Hub remains the primary source for many public and official images.
• Cloud-Native Workloads: If heavily invested in AWS, Azure, or GCP, using their respective native registries (ECR, ACR, Artifact Registry) usually provides the smoothest integration, best performance within the cloud, and unified access control.
• Multi-Cloud/Hybrid: Docker Hub or potentially a self-hosted registry might offer more neutrality.
• Multi-Artifact Needs: Google Artifact Registry stands out if you need to store container images alongside other package types (Java, Node.js, Python).
• Cost Sensitivity: Analyze storage and egress costs based on expected usage. Docker Hub's free tier is generous for public work but limited for private repos and subject to pull limits. Cloud provider costs depend heavily on usage patterns.

9. Conclusion

Choosing a container registry involves balancing factors like cost, performance, security, and ecosystem integration. Docker Hub is the universal public choice, while AWS ECR, Azure ACR, and Google Artifact Registry offer compelling advantages for users within their respective cloud ecosystems, providing tighter integration, platform-specific security features, and potentially better performance for cloud-deployed applications.

For new GCP users, Artifact Registry is the recommended path forward, replacing the older GCR. Evaluate your specific needs, particularly your cloud strategy and security requirements, to select the registry that best fits your workflow.

10. Additional Resources

Related Articles

• Docker Commands Guide
• Docker Compose Guide
• Choosing a Cloud Provider (AWS vs GCP vs Azure)
• Getting Started with Kubernetes (k8s)
• Securing Docker Containers

External Links

• Docker Hub
• Google Artifact Registry Documentation
• Amazon Elastic Container Registry (ECR)
• Azure Container Registry (ACR)
• Docker Concepts: Registries (Docker Docs)
• Transitioning from Google Container Registry (GCP Docs)