enable OCI artifact for attestation manifest by default

Signed-off-by: CrazyMax <[email protected]>

Author: crazy-max

README.md

@@ -284,7 +284,7 @@ Keys supported by image output:
 * `push-by-digest=true`: push unnamed image
 * `registry.insecure=true`: push to insecure HTTP registry
 * `oci-mediatypes=true`: use OCI mediatypes in configuration JSON instead of Docker's
-* `oci-artifact=false`: use OCI artifact format for attestations
+* `oci-artifact=true`: use OCI artifact format for attestations
 * `unpack=true`: unpack image after creation (for use with containerd)
 * `dangling-name-prefix=<value>`: name image with `prefix@<digest>`, used for anonymous images
 * `name-canonical=true`: add additional canonical name `name@<digest>`

exporter/containerimage/export.go

@@ -77,6 +77,7 @@ func (e *imageExporter) Resolve(ctx context.Context, id int, opt map[string]stri
 			RefCfg: cacheconfig.RefConfig{
 				Compression: compression.New(compression.Default),
 			},
+			OCIArtifact:             true,
 			ForceInlineAttestations: true,
 		},
 		store: true,

exporter/oci/export.go

@@ -70,7 +70,8 @@ func (e *imageExporter) Resolve(ctx context.Context, id int, opt map[string]stri
 			RefCfg: cacheconfig.RefConfig{
 				Compression: compression.New(compression.Default),
 			},
-			OCITypes: e.opt.Variant == VariantOCI,
+			OCIArtifact: true,
+			OCITypes:    e.opt.Variant == VariantOCI,
 		},
 	}