Configuring Proxy Cache on an OVHcloud Managed Private Registry

Objective

Harbor provides a proxy cache feature that helps you mirror and cache images from external registries like Docker Hub, Github Container Registry, Quay, JFrog Artifactory Registry, etc. This improves performance and reduces rate limits imposed by external registries.

We strongly recommend using a Docker account (even a free one) to avoid rate limits when pulling images. Without authentication, Docker Hub enforces strict pull limits, which may cause failures when pulling frequently used images.

Requirements

• A running Managed Private Registry.
• Access to the Harbor Web UI (with admin access).
• A Docker Hub account (recommended to prevent rate limits).

Instructions

1. Enable proxy cache

1. Log in to Harbor Web UI as an Administrator.
2. Go to Administration, then Registries.
3. Click + New Endpoint, then select Docker Hub as the provider.
4. Fill in the details:
   • Registry Type: Docker Hub
   • Registry Name: (e.g., docker-hub-proxy)
   • Registry Endpoint: https://hub.docker.com
   • Access ID: (your Docker Hub username)
   • Access Secret: (your Docker Hub password or personal access token)
5. Click OK.

2. Create a proxy cache project

1. In the Harbor Web UI, go to Projects.
2. Click + New Project.
3. Enter a Project Name (e.g., docker-hub-mirror).
4. Select Proxy Cache.
5. Under Upstream Registry, choose the Docker Hub proxy registry created earlier.
6. Click Save.

3. Configure Docker to use Harbor proxy cache

3.1 Log in to the Managed Private Registry

docker login <your-managed-registry-domain> -u <username> -p <password>

3.2 Pull images via proxy cache

Instead of pulling directly from Docker Hub, use your Private Managed Registry as an intermediary:

docker pull <your-managed-registry-domain>/dockerhub-mirror/library/nginx:latest

Harbor will cache the image locally, so subsequent pulls will be much faster and won’t count against Docker Hub rate limits.

Benefits of using proxy cache

• ✅ Avoid Docker Hub rate limits (with authentication).
• ✅ Faster image pulls for frequently used images.
• ✅ Reduced dependency on external registries.
• ✅ Improved reliability by caching images locally.

Troubleshooting

Getting "Too Many Requests" errors

• Ensure you configured Docker Hub authentication in Harbor.

Conclusion

Using Harbor's proxy cache helps optimize Docker image pulls, avoiding rate limits and improving performance. Be sure to authenticate with Docker Hub in Harbor to prevent rate limit issues.