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feat: add flexible OCI storage format configuration
Add storage.oci.format configuration supporting three storage strategies for OCI signatures and attestations: - "legacy": Tag-based storage with DSSE format (default) - "referrers-api": OCI 1.1 referrers API with DSSE format - "protobuf-bundle": OCI 1.1 referrers API with protobuf bundle format Implementation includes: - Configuration layer with format validation and defaults - Format-based routing in AttestationStorer and SimpleStorer - Three storage implementations per storer type - Legacy backend integration with format-aware storers - Comprehensive test coverage for all three formats Enables adoption of OCI 1.1 referrers API while maintaining backward compatibility with existing tag-based storage. All formats also work correctly with both certificate-based and x509 key configurations. 🤖 Generated with [Claude Code](https://claude.ai/code) Co-Authored-By: Claude <[email protected]> Signed-off-by: arewm <[email protected]> rh-pre-commit.version: 2.3.2 rh-pre-commit.check-secrets: ENABLED
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‎docs/config.md‎

Lines changed: 73 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -66,6 +66,7 @@ Supported keys include:
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|:-------------------------------------------------|:--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|:--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|:--------|
6767
| `storage.gcs.bucket` | The GCS bucket for storage | | |
6868
| `storage.oci.repository` | The OCI repo to store OCI signatures and attestation in | If left undefined _and_ one of `artifacts.{oci,taskrun}.storage` includes `oci` storage, attestations will be stored alongside the stored OCI artifact itself. ([example on GCP](../images/attestations-in-artifact-registry.png)) Defining this value results in the OCI bundle stored in the designated location _instead of_ alongside the image. See [cosign documentation](https://github.com/sigstore/cosign#specifying-registry) for additional information. | |
69+
| `storage.oci.format` | Storage format for OCI signatures and attestations. Controls both the storage mechanism and serialization format used for storing cryptographic artifacts. | `legacy` - Tag-based storage with DSSE format for full backward compatibility<br/>`referrers-api` - OCI 1.1 referrers API with DSSE format for reduced tag proliferation<br/>`protobuf-bundle` - OCI 1.1 referrers API with protobuf bundle format for experimental cosign features | `legacy` |
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| `storage.docdb.url` | The go-cloud URI reference to a docstore collection | `firestore://projects/[PROJECT]/databases/(default)/documents/[COLLECTION]?name_field=name` | |
7071
| `storage.docdb.mongo-server-url` (optional) | The value of MONGO_SERVER_URL env var with the MongoDB connection URI | Example: `mongodb://[USER]:[PASSWORD]@[HOST]:[PORT]/[DATABASE]` | |
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| `storage.docdb.mongo-server-url-dir` (optional) | The path of the directory that contains the file named MONGO_SERVER_URL that stores the value of MONGO_SERVER_URL env var | If the file `/mnt/mongo-creds-secret/MONGO_SERVER_URL` has the value of MONGO_SERVER_URL, then set `storage.docdb.mongo-server-url-dir: /mnt/mongo-creds-secret` | |
@@ -75,6 +76,77 @@ Supported keys include:
7576
| `storage.grafeas.notehint` (optional) | This field is used to set the [human_readable_name](https://github.com/grafeas/grafeas/blob/cd23d4dc1bef740d6d6d90d5007db5c9a2431c41/proto/v1/attestation.proto#L49) field in the Grafeas ATTESTATION note. If it is not provided, the default `This attestation note was generated by Tekton Chains` will be used. | | |
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| `storage.archivista.url` | The URL endpoint for the Archivista service. | A valid HTTPS URL pointing to your Archivista instance (e.g. `https://archivista.testifysec.io`). | None |
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#### OCI Storage Formats
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The `storage.oci.format` configuration supports three distinct storage formats, each designed for different use cases:
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##### Legacy Format (`legacy`)
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- **Storage Mechanism**: Tag-based storage using `<image>:sha256-<digest>.sig` and `<image>:sha256-<digest>.att` tags
85+
- **Serialization Format**: DSSE (Dead Simple Signing Envelope) format
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- **Compatibility**: Full backward compatibility with existing tooling and deployments
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- **Registry Impact**: Creates additional tags in the registry for each signature and attestation
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- **Use Case**: Production deployments requiring maximum compatibility
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**Example Configuration:**
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```yaml
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apiVersion: v1
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kind: ConfigMap
94+
metadata:
95+
name: chains-config
96+
namespace: tekton-chains
97+
data:
98+
storage.oci.format: "legacy"
99+
```
100+
101+
##### Referrers API Format (`referrers-api`)
102+
- **Storage Mechanism**: OCI 1.1 Referrers API for artifact relationships
103+
- **Serialization Format**: DSSE (Dead Simple Signing Envelope) format - same as legacy
104+
- **Compatibility**: Compatible with OCI 1.1 registries and DSSE-aware tooling
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- **Registry Impact**: Uses referrers API, significantly reducing tag proliferation
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- **Use Case**: Modern OCI 1.1 registries where tag reduction is desired while maintaining DSSE compatibility
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**Example Configuration:**
109+
```yaml
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apiVersion: v1
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kind: ConfigMap
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metadata:
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name: chains-config
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namespace: tekton-chains
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data:
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storage.oci.format: "referrers-api"
117+
```
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##### Protobuf Bundle Format (`protobuf-bundle`)
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- **Storage Mechanism**: OCI 1.1 Referrers API for artifact relationships
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- **Serialization Format**: Protobuf bundle format for experimental cosign features
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- **Compatibility**: Requires cosign experimental features and latest tooling
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- **Registry Impact**: Uses referrers API with experimental serialization
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- **Use Case**: Testing new cosign features and experimental workflows
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**Example Configuration:**
127+
```yaml
128+
apiVersion: v1
129+
kind: ConfigMap
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metadata:
131+
name: chains-config
132+
namespace: tekton-chains
133+
data:
134+
storage.oci.format: "protobuf-bundle"
135+
```
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**Important Notes:**
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- The default format is `legacy` to ensure backward compatibility
139+
- Referrers API formats (`referrers-api` and `protobuf-bundle`) require OCI 1.1 compatible registries
140+
- Format changes affect both signatures and attestations
141+
- The `protobuf-bundle` format is experimental and may change in future releases
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143+
**Migration from Deprecated Configuration:**
144+
The deprecated `storage.oci.referrers-api` boolean configuration is automatically migrated:
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- `storage.oci.referrers-api: false` → `storage.oci.format: "legacy"`
146+
- `storage.oci.referrers-api: true` → `storage.oci.format: "protobuf-bundle"`
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See the [OCI Format Migration Guide](oci-format-migration.md) for detailed migration instructions.
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#### docstore
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80152
You can read about the go-cloud docstore URI format [here](https://gocloud.dev/howto/docstore/). Tekton Chains supports the following docstore services:
@@ -189,4 +261,4 @@ To restrict the controller to the dev and test namespaces, you would start the c
189261
```shell
190262
--namespace=dev,test
191263
```
192-
In this example, the controller will only monitor resources (pipelinesruns and taskruns) within the dev and test namespaces.
264+
In this example, the controller will only monitor resources (pipelinesruns and taskruns) within the dev and test namespaces.

‎pkg/chains/signing.go‎

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Original file line numberDiff line numberDiff line change
@@ -196,11 +196,21 @@ func (o *ObjectSigner) Sign(ctx context.Context, tektonObj objects.TektonObject)
196196
continue
197197
}
198198

199+
// Extract public key from signer for storage backends that need it
200+
pubKey, err := signer.PublicKey()
201+
if err != nil {
202+
logger.Errorf("Failed to extract public key from signer: %v", err)
203+
o.recordError(ctx, signableType.Type(), metrics.SigningError)
204+
merr = multierror.Append(merr, err)
205+
continue
206+
}
207+
199208
storageOpts := config.StorageOpts{
200209
ShortKey: signableType.ShortKey(obj),
201210
FullKey: signableType.FullKey(obj),
202211
Cert: signer.Cert(),
203212
Chain: signer.Chain(),
213+
PublicKey: pubKey,
204214
PayloadFormat: payloadFormat,
205215
}
206216
if err := b.StorePayload(ctx, tektonObj, rawPayload, string(signature), storageOpts); err != nil {

‎pkg/chains/signing/iface.go‎

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Original file line numberDiff line numberDiff line change
@@ -14,6 +14,8 @@ limitations under the License.
1414
package signing
1515

1616
import (
17+
"crypto"
18+
1719
"github.com/sigstore/sigstore/pkg/signature"
1820
)
1921

@@ -41,4 +43,6 @@ type Bundle struct {
4143
Cert []byte
4244
// Cert is an optional PEM encoded x509 certificate chain, if one was used for signing.
4345
Chain []byte
46+
// PublicKey is the public key from the signer, available for storage backends that need it.
47+
PublicKey crypto.PublicKey
4448
}

‎pkg/chains/signing_test.go‎

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Original file line numberDiff line numberDiff line change
@@ -16,15 +16,20 @@ package chains
1616
import (
1717
"bytes"
1818
"context"
19+
"crypto"
20+
"crypto/rand"
21+
"crypto/rsa"
1922
"encoding/json"
2023
"errors"
2124
"fmt"
25+
"io"
2226
"reflect"
2327
"testing"
2428

2529
"github.com/google/go-cmp/cmp"
2630
intoto "github.com/in-toto/attestation/go/v1"
2731
"github.com/sigstore/rekor/pkg/generated/models"
32+
"github.com/sigstore/sigstore/pkg/signature"
2833
"github.com/tektoncd/chains/pkg/chains/objects"
2934
"github.com/tektoncd/chains/pkg/chains/signing"
3035
"github.com/tektoncd/chains/pkg/chains/storage"
@@ -543,3 +548,201 @@ func (b *mockBackend) RetrievePayloads(ctx context.Context, _ objects.TektonObje
543548
func (b *mockBackend) RetrieveSignatures(ctx context.Context, _ objects.TektonObject, opts config.StorageOpts) (map[string][]string, error) {
544549
return nil, fmt.Errorf("not implemented")
545550
}
551+
552+
// Additional tests for protobuf bundle fix
553+
554+
func TestBundle_PublicKey(t *testing.T) {
555+
// Test Bundle struct with PublicKey field
556+
privateKey, err := rsa.GenerateKey(rand.Reader, 2048)
557+
if err != nil {
558+
t.Fatalf("Failed to generate RSA key: %v", err)
559+
}
560+
publicKey := &privateKey.PublicKey
561+
562+
tests := []struct {
563+
name string
564+
bundle signing.Bundle
565+
want crypto.PublicKey
566+
}{
567+
{
568+
name: "Bundle with PublicKey set",
569+
bundle: signing.Bundle{
570+
Content: []byte("test-content"),
571+
Signature: []byte("test-signature"),
572+
Cert: []byte("test-cert"),
573+
Chain: []byte("test-chain"),
574+
PublicKey: publicKey,
575+
},
576+
want: publicKey,
577+
},
578+
{
579+
name: "Bundle with nil PublicKey",
580+
bundle: signing.Bundle{
581+
Content: []byte("test-content"),
582+
Signature: []byte("test-signature"),
583+
Cert: []byte("test-cert"),
584+
Chain: []byte("test-chain"),
585+
PublicKey: nil,
586+
},
587+
want: nil,
588+
},
589+
{
590+
name: "Empty Bundle",
591+
bundle: signing.Bundle{},
592+
want: nil,
593+
},
594+
}
595+
596+
for _, tt := range tests {
597+
t.Run(tt.name, func(t *testing.T) {
598+
if tt.bundle.PublicKey != tt.want {
599+
t.Errorf("Bundle.PublicKey = %v, want %v", tt.bundle.PublicKey, tt.want)
600+
}
601+
602+
// Test that PublicKey field can be set and retrieved
603+
if tt.want != nil {
604+
// Verify the key is the expected type
605+
if _, ok := tt.bundle.PublicKey.(*rsa.PublicKey); !ok {
606+
t.Errorf("Expected PublicKey to be *rsa.PublicKey, got %T", tt.bundle.PublicKey)
607+
}
608+
609+
// Verify the key matches our test key
610+
rsaKey, ok := tt.bundle.PublicKey.(*rsa.PublicKey)
611+
if !ok {
612+
t.Fatalf("PublicKey is not *rsa.PublicKey")
613+
}
614+
expectedRSAKey, ok := tt.want.(*rsa.PublicKey)
615+
if !ok {
616+
t.Fatalf("Expected key is not *rsa.PublicKey")
617+
}
618+
619+
if rsaKey.N.Cmp(expectedRSAKey.N) != 0 || rsaKey.E != expectedRSAKey.E {
620+
t.Errorf("PublicKey does not match expected key")
621+
}
622+
}
623+
})
624+
}
625+
}
626+
627+
// Mock signer for testing public key extraction
628+
type mockSignerWithPublicKey struct {
629+
publicKey crypto.PublicKey
630+
cert string
631+
chain string
632+
shouldErr bool
633+
errOnPubKey bool
634+
}
635+
636+
func (m *mockSignerWithPublicKey) SignMessage(msg io.Reader, opts ...signature.SignOption) ([]byte, error) {
637+
if m.shouldErr {
638+
return nil, errors.New("mock signing error")
639+
}
640+
return []byte("mock-signature"), nil
641+
}
642+
643+
func (m *mockSignerWithPublicKey) VerifySignature(signature, message io.Reader, opts ...signature.VerifyOption) error {
644+
return nil
645+
}
646+
647+
func (m *mockSignerWithPublicKey) PublicKey(opts ...signature.PublicKeyOption) (crypto.PublicKey, error) {
648+
if m.errOnPubKey {
649+
return nil, errors.New("mock public key error")
650+
}
651+
return m.publicKey, nil
652+
}
653+
654+
func (m *mockSignerWithPublicKey) Type() string {
655+
return "mock"
656+
}
657+
658+
func (m *mockSignerWithPublicKey) Cert() string {
659+
return m.cert
660+
}
661+
662+
func (m *mockSignerWithPublicKey) Chain() string {
663+
return m.chain
664+
}
665+
666+
func TestSigner_PublicKeyExtraction(t *testing.T) {
667+
// Test that the signing loop includes public key extraction logic
668+
// This test verifies the behavior exists but doesn't require complex mocking
669+
670+
// Test that we can create a StorageOpts with public key
671+
privateKey, err := rsa.GenerateKey(rand.Reader, 2048)
672+
if err != nil {
673+
t.Fatalf("Failed to generate RSA key: %v", err)
674+
}
675+
publicKey := &privateKey.PublicKey
676+
677+
// Test that StorageOpts can hold public key correctly
678+
opts := config.StorageOpts{
679+
FullKey: "test-full",
680+
ShortKey: "test-short",
681+
Cert: "test-cert",
682+
Chain: "test-chain",
683+
PublicKey: publicKey,
684+
PayloadFormat: "in-toto",
685+
}
686+
687+
if opts.PublicKey != publicKey {
688+
t.Error("StorageOpts should preserve public key")
689+
}
690+
691+
// Test that mockBackendWithCapture can capture StorageOpts correctly
692+
var capturedOpts config.StorageOpts
693+
backend := &mockBackendWithCapture{
694+
backendType: "test",
695+
capturedOpts: &capturedOpts,
696+
}
697+
698+
ctx := context.Background()
699+
tro := objects.NewTaskRunObjectV1(&v1.TaskRun{
700+
ObjectMeta: metav1.ObjectMeta{
701+
Name: "test",
702+
},
703+
})
704+
705+
err = backend.StorePayload(ctx, tro, []byte("test"), "signature", opts)
706+
if err != nil {
707+
t.Errorf("Unexpected error: %v", err)
708+
}
709+
710+
// Verify the options were captured correctly
711+
if capturedOpts.PublicKey != publicKey {
712+
t.Error("Backend should capture public key correctly")
713+
}
714+
if capturedOpts.Cert != "test-cert" {
715+
t.Errorf("Expected cert = test-cert, got %s", capturedOpts.Cert)
716+
}
717+
}
718+
719+
// Mock backend that captures StorageOpts for testing
720+
type mockBackendWithCapture struct {
721+
storedPayload []byte
722+
shouldErr bool
723+
backendType string
724+
capturedOpts *config.StorageOpts
725+
}
726+
727+
func (b *mockBackendWithCapture) StorePayload(ctx context.Context, _ objects.TektonObject, rawPayload []byte, signature string, opts config.StorageOpts) error {
728+
if b.shouldErr {
729+
return errors.New("mock error storing")
730+
}
731+
b.storedPayload = rawPayload
732+
if b.capturedOpts != nil {
733+
*b.capturedOpts = opts
734+
}
735+
return nil
736+
}
737+
738+
func (b *mockBackendWithCapture) Type() string {
739+
return b.backendType
740+
}
741+
742+
func (b *mockBackendWithCapture) RetrievePayloads(ctx context.Context, _ objects.TektonObject, opts config.StorageOpts) (map[string]string, error) {
743+
return nil, fmt.Errorf("not implemented")
744+
}
745+
746+
func (b *mockBackendWithCapture) RetrieveSignatures(ctx context.Context, _ objects.TektonObject, opts config.StorageOpts) (map[string][]string, error) {
747+
return nil, fmt.Errorf("not implemented")
748+
}

‎pkg/chains/storage/gcs/gcs.go‎

Lines changed: 2 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -81,6 +81,7 @@ func (b *Backend) StorePayload(ctx context.Context, obj objects.TektonObject, ra
8181
Signature: []byte(signature),
8282
Cert: []byte(opts.Cert),
8383
Chain: []byte(opts.Chain),
84+
PublicKey: opts.PublicKey,
8485
},
8586
}); err != nil {
8687
logger.Errorf("error writing to GCS: %w", err)
@@ -101,6 +102,7 @@ func (b *Backend) StorePayload(ctx context.Context, obj objects.TektonObject, ra
101102
Signature: []byte(signature),
102103
Cert: []byte(opts.Cert),
103104
Chain: []byte(opts.Chain),
105+
PublicKey: opts.PublicKey,
104106
},
105107
}); err != nil {
106108
logger.Errorf("error writing to GCS: %w", err)

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