# Registry Compatibility Quick Reference

> Sprint: SPRINT_0127_001_0002_oci_registry_compatibility
> Module: Doctor

Quick reference for OCI registry compatibility with StellaOps. For detailed information, see [Registry Diagnostic Checks](../modules/doctor/registry-checks.md).

## Quick Compatibility Check

```bash
# Run all registry diagnostics
stella doctor --tag registry

# Check specific capability
stella doctor --check check.integration.oci.referrers

# Export detailed report
stella doctor --tag registry --format json --output registry-report.json
```

## Supported Registries

| Registry | Referrers API | Recommendation |
|----------|---------------|----------------|
| ACR, ECR, GCR, Harbor 2.6+, Quay 3.12+, JFrog 7.x+, Zot | Native | Full support |
| GHCR, Docker Hub, registry:2 | Fallback | Supported with automatic fallback |

## Common Issues

| Symptom | Check | Likely Cause | Fix |
|---------|-------|--------------|-----|
| "Invalid credentials" | `oci.credentials` | Wrong username/password | Verify credentials, check expiry |
| "No pull permission" | `oci.pull` | Missing reader role | Grant pull/read access |
| "No push permission" | `oci.push` | Missing writer role | Grant push/write access |
| "Referrers API not supported" | `oci.referrers` | Old registry version | Upgrade or use fallback |
| "Artifacts missing in bundle" | `oci.referrers` | Referrers not discovered | Check registry compatibility |

## Registry-Specific Notes

### GHCR (GitHub Container Registry)
- Referrers API not implemented
- StellaOps uses tag-based fallback automatically
- No action required

### Harbor
- Requires version 2.6+ for native referrers API
- Older versions work with fallback

### Docker Hub
- Rate limits may affect probes
- Use authenticated requests for higher limits

## Verification Commands

```bash
# Test registry connectivity
curl -I https://registry.example.com/v2/

# Test referrers API
curl -H "Accept: application/vnd.oci.image.index.v1+json" \
  "https://registry.example.com/v2/repo/referrers/sha256:..."

# Test with docker CLI
docker login registry.example.com
docker pull registry.example.com/repo:tag
```

## See Also

- [Detailed registry checks](../modules/doctor/registry-checks.md)
- [Registry referrer troubleshooting](./registry-referrer-troubleshooting.md)
- [Export Center registry compatibility](../modules/export-center/registry-compatibility.md)