Fixes value for storage.oci.repository

Previously while providing repo url value for storage
oci repository, chains controller was giving an error
as

`a digest must contain exactly one '@' separator (e.g.
registry/repository@digest)`

because, it was not able to add digest

Hence this patch fixes it, by formatting the value
provided by the user and thus storing the
attestations/signatures in the provided location

Signed-off-by: PuneetPunamiya <ppunamiy@redhat.com>

pkg/chains/storage/oci/legacy.go

@@ -18,27 +18,23 @@ import (
 	"encoding/base64"
 	"encoding/json"
 	"fmt"
-
-	"github.com/tektoncd/chains/pkg/chains/formats"
-	"github.com/tektoncd/chains/pkg/chains/objects"
-	"github.com/tektoncd/chains/pkg/chains/signing"
-	"github.com/tektoncd/chains/pkg/chains/storage/api"
-
-	"knative.dev/pkg/logging"
-
-	"github.com/in-toto/in-toto-golang/in_toto"
-	"github.com/secure-systems-lab/go-securesystemslib/dsse"
-
 	"github.com/google/go-containerregistry/pkg/authn/k8schain"
 	"github.com/google/go-containerregistry/pkg/name"
 	"github.com/google/go-containerregistry/pkg/v1/remote"
+	"github.com/in-toto/in-toto-golang/in_toto"
 	"github.com/pkg/errors"
+	"github.com/secure-systems-lab/go-securesystemslib/dsse"
 	"github.com/sigstore/cosign/v2/pkg/oci"
 	ociremote "github.com/sigstore/cosign/v2/pkg/oci/remote"
 	"github.com/tektoncd/chains/pkg/artifacts"
+	"github.com/tektoncd/chains/pkg/chains/formats"
 	"github.com/tektoncd/chains/pkg/chains/formats/simple"
+	"github.com/tektoncd/chains/pkg/chains/objects"
+	"github.com/tektoncd/chains/pkg/chains/signing"
+	"github.com/tektoncd/chains/pkg/chains/storage/api"
 	"github.com/tektoncd/chains/pkg/config"
 	"k8s.io/client-go/kubernetes"
+	"knative.dev/pkg/logging"
 )
 
 const StorageBackendOCI = "oci"
@@ -54,7 +50,8 @@ type Backend struct {
 // NewStorageBackend returns a new OCI StorageBackend that stores signatures in an OCI registry
 func NewStorageBackend(ctx context.Context, client kubernetes.Interface, cfg config.Config) *Backend {
 	return &Backend{
-		cfg:    cfg,
+		cfg: cfg,
+
 		client: client,
 		getAuthenticator: func(ctx context.Context, obj objects.TektonObject, client kubernetes.Interface) (remote.Option, error) {
 			kc, err := k8schain.New(ctx, client,
@@ -279,15 +276,25 @@ func (b *Backend) RetrieveArtifact(ctx context.Context, obj objects.TektonObject
 }
 
 func newDigest(cfg config.Config, imageName string) (name.Digest, error) {
-	// Override image name from config if set.
-	if r := cfg.Storage.OCI.Repository; r != "" {
-		imageName = r
-	}
-
 	var opts []name.Option
 	if cfg.Storage.OCI.Insecure {
 		opts = append(opts, name.Insecure)
 	}
 
+	if storageOCIRepository := cfg.Storage.OCI.Repository; storageOCIRepository != "" {
+		digest, err := name.NewDigest(imageName, opts...)
+		if err != nil {
+			return name.Digest{}, err
+		}
+		digestSha := digest.DigestStr()
+
+		newRepo, err := name.NewRepository(storageOCIRepository)
+		if err != nil {
+			return name.Digest{}, err
+		}
+
+		imageName = newRepo.Digest(digestSha).Name()
+	}
+
 	return name.NewDigest(imageName, opts...)
 }

pkg/chains/storage/oci/legacy_test.go

@@ -0,0 +1,38 @@
+package oci
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/tektoncd/chains/pkg/config"
+)
+
+func TestStorageOCIRepo(t *testing.T) {
+	cfg := config.Config{}
+	cfg.Storage.OCI.Repository = "quay.io/concaf"
+	tests := []struct {
+		testImageName     string
+		expectedImageName string
+	}{
+		{
+			testImageName:     "gcr.io/tekton-releases/github.com/tektoncd/pipeline/cmd/git-init@sha256:bc4f7468f87486e3835b09098c74cd7f54db2cf697cbb9b824271b95a2d0871e",
+			expectedImageName: "quay.io/concaf@sha256:bc4f7468f87486e3835b09098c74cd7f54db2cf697cbb9b824271b95a2d0871e",
+		},
+		{
+			testImageName:     "docker.io/puneet2147/kaniko-chains@sha256:bc4f7468f87486e3835b09098c74cd7f54db2cf697cbb9b824271b95a2d0871e",
+			expectedImageName: "quay.io/concaf@sha256:bc4f7468f87486e3835b09098c74cd7f54db2cf697cbb9b824271b95a2d0871e",
+		},
+		{
+			testImageName:     "registry.com/spam/spam/spam/spam/spam/spam@sha256:bc4f7468f87486e3835b09098c74cd7f54db2cf697cbb9b824271b95a2d0871e",
+			expectedImageName: "quay.io/concaf@sha256:bc4f7468f87486e3835b09098c74cd7f54db2cf697cbb9b824271b95a2d0871e",
+		},
+	}
+
+	for _, test := range tests {
+		digest, err := newDigest(cfg, test.testImageName)
+		if err != nil {
+			t.Error(err)
+		}
+		assert.Equal(t, digest.Name(), test.expectedImageName)
+	}
+}