docker/compose · error

%s is not a compose project OCI artifact, but %s

Error message

%s is not a compose project OCI artifact, but %s

What it means

pullComposeFiles validates the fetched manifest before extracting layers: either manifest.ArtifactType is set and must equal oci.ComposeProjectArtifactType, or — when it is empty — manifest.Config.MediaType must be the compose empty-config media type. Anything else means the manifest is not a compose project artifact, and the message reports the ref and the offending artifact type.

Source

Thrown at pkg/remote/oci.go:208

			}
		}
		g.known[path] = local
	}
	return filepath.Join(local, "compose.yaml"), nil
}

func (g *ociRemoteLoader) Dir(path string) string {
	return g.known[path]
}

func (g *ociRemoteLoader) pullComposeFiles(ctx context.Context, local string, manifest spec.Manifest, ref reference.Named, resolver remotes.Resolver) error {
	err := os.MkdirAll(local, 0o700)
	if err != nil {
		return err
	}
	if (manifest.ArtifactType != "" && manifest.ArtifactType != oci.ComposeProjectArtifactType) ||
		(manifest.ArtifactType == "" && manifest.Config.MediaType != oci.ComposeEmptyConfigMediaType) {
		return fmt.Errorf("%s is not a compose project OCI artifact, but %s", ref.String(), manifest.ArtifactType)
	}

	for i, layer := range manifest.Layers {
		content, err := oci.GetBlob(ctx, resolver, ref, layer)
		if err != nil {
			return err
		}

		switch layer.MediaType {
		case oci.ComposeYAMLMediaType:
			if err := writeComposeFile(layer, i, local, content); err != nil {
				return err
			}
		case oci.ComposeEnvFileMediaType:
			if err := writeEnvFile(layer, local, content); err != nil {
				return err
			}
		case oci.ComposeEmptyConfigMediaType:

View on GitHub (pinned to ddc4b044b6)

Solutions

1. Inspect the manifest (`docker buildx imagetools inspect <ref> --raw`) and check artifactType/config.mediaType against what docker compose publishes.
2. Re-push the resource as a compose bundle with `docker compose push` from a supported compose version so the correct artifact/config types are set.
3. If the resource is a normal image, stop using it via oci:// in -f and reference it as a service image instead.

// when building bundles yourself, assert the manifest type before publishing
if manifest.ArtifactType != "" && manifest.ArtifactType != ComposeProjectArtifactType {
    return fmt.Errorf("refusing to publish %q as a compose bundle", manifest.ArtifactType)
}

When it happens

Trigger: A manifest whose ArtifactType is a foreign value (e.g. application/vnd.example.something) or whose config media type is a normal image config (application/vnd.oci.image.config.v1+json) when ArtifactType is empty. Reached when the top-level descriptor is a single manifest (not an index), or after fetching the compose-flagged manifest from an index.

Common situations: Pointing compose at a plain container image manifest rather than a bundle; bundles produced by non-docker tooling that uses its own artifact types; partially migrated images that have a compose layer but standard config media type.

Related errors

• OCI index %s doesn't refer to compose artifacts
• missing annotation com.docker.compose.envfile in layer %q
• invalid digest %s: %w
• OCI remote resource is disabled by %q
• failed to pull OCI resource %q: %w

AI-assisted analysis of docker/compose@ddc4b044b6 (2026-08-15). Data as JSON: /api/errors/963a822b43075972. Report an issue: GitHub.