Refactor the initialization of KeyManagers.

kms/kms.go

@@ -2,30 +2,18 @@ package kms
 
 import (
 	"context"
-	"crypto"
-	"crypto/x509"
 	"strings"
 
 	"github.com/pkg/errors"
 	"github.com/smallstep/certificates/kms/apiv1"
-	"github.com/smallstep/certificates/kms/cloudkms"
-	"github.com/smallstep/certificates/kms/softkms"
-	"github.com/smallstep/certificates/kms/yubikey"
 )
 
 // KeyManager is the interface implemented by all the KMS.
-type KeyManager interface {
-	GetPublicKey(req *apiv1.GetPublicKeyRequest) (crypto.PublicKey, error)
-	CreateKey(req *apiv1.CreateKeyRequest) (*apiv1.CreateKeyResponse, error)
-	CreateSigner(req *apiv1.CreateSignerRequest) (crypto.Signer, error)
-	Close() error
-}
+type KeyManager = apiv1.KeyManager
 
-// CertificateManager is the interface implemented by the KMS that can load and store x509.Certificates.
-type CertificateManager interface {
-	LoadCerticate(req *apiv1.LoadCertificateRequest) (*x509.Certificate, error)
-	StoreCertificate(req *apiv1.StoreCertificateRequest) error
-}
+// CertificateManager is the interface implemented by the KMS that can load and
+// store x509.Certificates.
+type CertificateManager = apiv1.CertificateManager
 
 // New initializes a new KMS from the given type.
 func New(ctx context.Context, opts apiv1.Options) (KeyManager, error) {
@@ -33,14 +21,14 @@ func New(ctx context.Context, opts apiv1.Options) (KeyManager, error) {
 		return nil, err
 	}
 
-	switch apiv1.Type(strings.ToLower(opts.Type)) {
-	case apiv1.DefaultKMS, apiv1.SoftKMS:
-		return softkms.New(ctx, opts)
-	case apiv1.CloudKMS:
-		return cloudkms.New(ctx, opts)
-	case apiv1.YubiKey:
-		return yubikey.New(ctx, opts)
-	default:
+	t := apiv1.Type(strings.ToLower(opts.Type))
+	if t == apiv1.DefaultKMS {
+		t = apiv1.SoftKMS
+	}
+
+	fn, ok := apiv1.LoadKeyManagerNewFunc(t)
+	if !ok {
 		return nil, errors.Errorf("unsupported kms type '%s'", opts.Type)
 	}
+	return fn(ctx, opts)
 }