# Repositories and OCI Registries — Helm

Source: https://www.skillbyai.com/en/helm/u-oci

> Pull and push charts from classic repositories and OCI registries.

## Two ways to distribute charts

A **classic chart repository** is any HTTP server hosting an `index.yaml` plus chart archives; you use it with `helm repo add` and refer to charts as `repo/chart`. Modern Helm also stores charts in **OCI registries**, the same registries that hold container images (GitHub Container Registry, Docker Hub, Amazon ECR, Google Artifact Registry, Azure Container Registry, Harbor). With OCI there is no `repo add` step: you log in with `helm registry login` and refer to charts by URL, `oci://registry/path/chart`, with `--version`. OCI is now the common choice for internal charts because you reuse existing registry authentication, access control, replication and scanning. **Artifact Hub** is a search index for public charts, not a repository itself.

## Packaging and pushing to an OCI registry

The chart name and version come from `Chart.yaml`; the push target is the parent path.

```bash
helm package ./charts/shop-api            # creates shop-api-1.4.0.tgz
helm registry login ghcr.io -u my-user    # token from stdin or prompt
helm push shop-api-1.4.0.tgz oci://ghcr.io/acme/charts

# consumers
helm show chart oci://ghcr.io/acme/charts/shop-api --version 1.4.0
helm upgrade --install shop-api oci://ghcr.io/acme/charts/shop-api \
  --version 1.4.0 -n shop -f values-prod.yaml
```

## Treat chart versions as immutable

Never push different content under an existing chart version. Clusters and caches may already hold the old artefact, and two environments would silently run different charts with the same number. Bump the version for every change.

**Quiz:** How do you install a chart from an OCI registry?

- [x] helm install NAME oci://registry/path/chart --version X
- [ ] helm repo add, then helm install repo/chart
- [ ] kubectl apply -f oci://...
- [ ] helm pull is required before any install

*Answer:* helm install NAME oci://registry/path/chart --version X. OCI charts are referenced directly by an oci:// URL; no repo add step is needed.