---
url: /en/artifact/supported-manifest-types.md
description: >
  Lists the manifest types currently accepted by CNB Docker, Helm, and Docker
  Model registries, including the config mediaType and typical scenarios for
  each type.
---
The Docker, Helm, and Docker Model registries are based on the OCI manifest protocol. They identify an artifact's type and accept or reject the push according to the [Artifact Type Admission Restrictions](./intro.md#artifact-type-admission-restrictions). Identification rules:

* The **config mediaType** determines the artifact type (e.g. `vnd.oci.image.config.v1+json` is classified as a container image).
* Some types require an **additional check on manifest layers** (e.g. an empty-config artifact is only recognized as Attestation when all of its layers are `application/vnd.in-toto+json` layers carrying the `in-toto.io/predicate-type` annotation; otherwise it is UNKNOWN).

::::: info Scope
This appendix only applies to the Docker, Helm, and Docker Model OCI registries.
Other registries such as Maven, npm, and PyPI use their own native protocols and do not involve manifest type identification.
:::::

## Docker Registry

| Artifact Type | config mediaType | Additional Condition | Typical Scenario |
|:---|:---|:---|:---|
| Container image (IMAGE) | `application/vnd.oci.image.config.v1+json` | — | Images pushed via `docker push` / `docker buildx build --push` |
| Container image (IMAGE) | `application/vnd.docker.container.image.v1+json` | — | Images in Docker schema2 format |
| buildx registry cache (BUILD\_CACHE) | `application/vnd.buildkit.cacheconfig.v0` | — | Build cache pushed via `docker buildx build --cache-to type=registry` |
| Attestation (ATTESTATION) | `application/vnd.oci.empty.v1+json` | config must be the standard empty descriptor (fixed digest, size 2), and all manifest layers must be `application/vnd.in-toto+json` layers carrying a non-empty `in-toto.io/predicate-type` annotation | Provenance/SBOM attestations produced by buildx builds |

The index of a multi-arch image (`application/vnd.oci.image.index.v1+json` or `application/vnd.docker.distribution.manifest.list.v2+json`) is accepted together with its child manifests and requires no separate configuration.

::::: warning Note

* **Attestation identification requires all of the following**: config is the standard `application/vnd.oci.empty.v1+json` empty descriptor (digest `sha256:44136fa355b3678a1146ad16f7e8649e94fb4fc21fe77e8310c060f61caaff8a`, size 2), **and** all manifest layers are `application/vnd.in-toto+json` layers carrying a non-empty `in-toto.io/predicate-type` annotation (i.e. a real buildkit provenance/SBOM), with at most 16 layers. An artifact that fails these conditions (e.g. a generic artifact pushed by `oras push` with default empty config, a forged in-toto mediaType without the predicate-type annotation, or one that mixes in non-in-toto layers) is classified as UNKNOWN and **will be rejected** when pushed to the Docker registry.
* Generic OCI artifacts with a custom config mediaType (e.g. `application/vnd.myapp.config.v1+json`) are currently **not supported** by the Docker registry and will be rejected.
* **Attestation identification is heuristic and does not constitute a supply chain security boundary**: manifest fields are controlled by the pusher and can theoretically be forged to bypass type checks. The registry only handles type routing and storage; it does not verify the authenticity or signature of attestation content.
  :::::

## Helm Registry

| Artifact Type | config mediaType | Typical Scenario |
|:---|:---|:---|
| Helm Chart (CHART) | `application/vnd.cncf.helm.config.v1+json` | `helm push` (OCI format) |

## Docker Model Registry

| Artifact Type | config mediaType | Typical Scenario |
|:---|:---|:---|
| Docker Model (DockerModel) | `application/vnd.docker.ai.model.config.v0.1+json` | `docker model push` |

## Rejection Error

When pushing a type that is not on the allowlist, the following error is returned. Blobs already uploaded are cleaned up automatically by garbage collection (GC):

```text
denied: artifact type "CHART" is not allowed to be pushed to a "docker" registry
```