Merge pull request moby#50426 from thaJeztah/no_empty_auth

api/types/registry: EncodeAuthConfig: use empty string for zero value

Author: thaJeztah

api/types/registry/authconfig.go

@@ -52,6 +52,9 @@ type AuthConfig struct {
 //
 // [RFC4648, section 5]: https://tools.ietf.org/html/rfc4648#section-5
 func EncodeAuthConfig(authConfig AuthConfig) (string, error) {
+	if authConfig == (AuthConfig{}) {
+		return "", nil
+	}
 	buf, err := json.Marshal(authConfig)
 	if err != nil {
 		return "", errInvalidParameter{err}

api/types/registry/authconfig_test.go

@@ -111,8 +111,8 @@ func TestEncodeAuthConfig(t *testing.T) {
 		{
 			doc:       "empty",
 			input:     AuthConfig{},
-			outBase64: `e30=`,
-			outPlain:  `{}`,
+			outBase64: ``,
+			outPlain:  ``,
 		},
 		{
 			doc: "test authConfig",