Fix key version tracking in Azure Key Vault

vault/seal/azurekeyvault/azurekeyvault.go

@@ -124,10 +124,14 @@ func (v *AzureKeyVaultSeal) SetConfig(config map[string]string) (map[string]stri
 		}
 
 		// Test the client connection using provided key ID
-		_, err = client.GetKey(context.Background(), v.buildBaseURL(), v.keyName, "")
+		keyInfo, err := client.GetKey(context.Background(), v.buildBaseURL(), v.keyName, "")
 		if err != nil {
 			return nil, errwrap.Wrapf("error fetching Azure Key Vault seal key information: {{err}}", err)
 		}
+		if keyInfo.Key == nil {
+			return nil, errors.New("no key information returned")
+		}
+		v.currentKeyID.Store(parseKeyVersion(to.String(keyInfo.Key.Kid)))
 
 		v.client = client
 	}
@@ -185,10 +189,9 @@ func (v *AzureKeyVaultSeal) Encrypt(ctx context.Context, plaintext []byte) (*phy
 		return nil, err
 	}
 
-	// Kid gets returned as a full URL, get the last bit which is just
-	// the version
-	keyVersionParts := strings.Split(to.String(resp.Kid), "/")
-	keyVersion := keyVersionParts[len(keyVersionParts)-1]
+	// Store the current key version
+	keyVersion := parseKeyVersion(to.String(resp.Kid))
+	v.currentKeyID.Store(keyVersion)
 
 	ret := &physical.EncryptedBlobInfo{
 		Ciphertext: env.Ciphertext,
@@ -265,3 +268,10 @@ func (v *AzureKeyVaultSeal) getKeyVaultClient() (*keyvault.BaseClient, error) {
 	client.Authorizer = authorizer
 	return &client, nil
 }
+
+// Kid gets returned as a full URL, get the last bit which is just
+// the version
+func parseKeyVersion(kid string) string {
+	keyVersionParts := strings.Split(kid, "/")
+	return keyVersionParts[len(keyVersionParts)-1]
+}

vault/seal/azurekeyvault/azurekeyvault_acc_test.go

@@ -40,6 +40,10 @@ func TestAzureKeyVault_Lifecycle(t *testing.T) {
 	}
 
 	s := NewSeal(logging.NewVaultLogger(log.Trace))
+	_, err := s.SetConfig(nil)
+	if err != nil {
+		t.Fatalf("err: %s", err.Error())
+	}
 
 	// Test Encrypt and Decrypt calls
 	input := []byte("foo")