oci: Introduce Flux media types

Signed-off-by: Stefan Prodan <stefan.prodan@gmail.com>

oci/client/push.go

@@ -28,6 +28,10 @@ import (
  gcrv1 "github.com/google/go-containerregistry/pkg/v1"
  "github.com/google/go-containerregistry/pkg/v1/empty"
  "github.com/google/go-containerregistry/pkg/v1/mutate"
+ "github.com/google/go-containerregistry/pkg/v1/tarball"
+ "github.com/google/go-containerregistry/pkg/v1/types"
+
+ "github.com/fluxcd/pkg/oci"
 )
 
 // Push creates an artifact from the given directory, uploads the artifact
@@ -50,14 +54,21 @@ func (c *Client) Push(ctx context.Context, url, sourceDir string, meta Metadata,
  return "", err
  }
 
- img, err := crane.Append(empty.Image, tmpFile)
+ ct := time.Now()
+ meta.Created = ct.Format(time.RFC3339)
+
+ img := mutate.MediaType(empty.Image, types.OCIManifestSchema1)
+ img = mutate.ConfigMediaType(img, oci.ConfigMediaType)
+ img = mutate.Annotations(img, meta.ToAnnotations()).(gcrv1.Image)
+
+ layer, err := tarball.LayerFromFile(tmpFile, tarball.WithMediaType(oci.ContentMediaType))
  if err != nil {
  return "", fmt.Errorf("appeding content to artifact failed: %w", err)
  }
 
- ct := time.Now()
- meta.Created = ct.Format(time.RFC3339)
- img = mutate.Annotations(img, meta.ToAnnotations()).(gcrv1.Image)
+ img, err = mutate.Append(img, mutate.Addendum{
+  Layer: layer,
+ })
 
  if err := crane.Push(img, url, c.optionsWithContext(ctx)...); err != nil {
  return "", fmt.Errorf("pushing artifact failed: %w", err)

oci/constants.go

@@ -37,6 +37,12 @@ const (
 )
 
 const (
+ // ConfigMediaType is the OCI media type for the config layer.
+ ConfigMediaType = "application/vnd.cncf.flux.config.v1+json"
+
+ // ContentMediaType is the OCI media type for the content layer.
+ ContentMediaType = "application/vnd.cncf.flux.content.v1.tar+gzip"
+
  // SourceAnnotation is the OpenContainers annotation for specifying
  // the upstream source of an OCI artifact.
  SourceAnnotation = "org.opencontainers.image.source"