Allow username/password in config file

Signed-off-by: Jon Johnson <jonjohnson@google.com>

cli/config/configfile/file.go

@@ -123,9 +123,11 @@ func (configFile *ConfigFile) LoadFromReader(configData io.Reader) error {
 	}
 	var err error
 	for addr, ac := range configFile.AuthConfigs {
-		ac.Username, ac.Password, err = decodeAuth(ac.Auth)
-		if err != nil {
-			return err
+		if ac.Auth != "" {
+			ac.Username, ac.Password, err = decodeAuth(ac.Auth)
+			if err != nil {
+				return err
+			}
 		}
 		ac.Auth = ""
 		ac.ServerAddress = addr

cli/config/configfile/file_test.go

@@ -2,6 +2,7 @@ package configfile
 
 import (
 	"bytes"
+	"encoding/json"
 	"io/ioutil"
 	"os"
 	"testing"
@@ -380,6 +381,33 @@ func TestGetAllCredentialsCredHelperOverridesDefaultStore(t *testing.T) {
 	assert.Check(t, is.Equal(0, testCredHelper.(*mockNativeStore).GetAllCallCount))
 }
 
+func TestLoadFromReaderWithUsernamePassword(t *testing.T) {
+	configFile := New("test-load")
+	defer os.Remove("test-load")
+
+	want := types.AuthConfig{
+		Username: "user",
+		Password: "pass",
+	}
+	cf := ConfigFile{
+		AuthConfigs: map[string]types.AuthConfig{
+			"example.com/foo": want,
+		},
+	}
+
+	b, err := json.Marshal(cf)
+	assert.NilError(t, err)
+
+	err = configFile.LoadFromReader(bytes.NewReader(b))
+	assert.NilError(t, err)
+
+	got, err := configFile.GetAuthConfig("example.com/foo")
+	assert.NilError(t, err)
+
+	assert.Check(t, is.DeepEqual(want.Username, got.Username))
+	assert.Check(t, is.DeepEqual(want.Password, got.Password))
+}
+
 func TestCheckKubernetesConfigurationRaiseAnErrorOnInvalidValue(t *testing.T) {
 	testCases := []struct {
 		name        string