Fix error handling in to parse ignoreFields (#4295)

* Fix error handling

* Add valide function to DriftDetection

pkg/app/piped/driftdetector/kubernetes/detector.go

@@ -198,9 +198,6 @@ func (d *detector) checkApplication(ctx context.Context, app *model.Application,
 		for _, ignoreField := range ddCfg.IgnoreFields {
 			// ignoreField is 'apiVersion:kind:namespace:name#fieldPath'
 			splited := strings.Split(ignoreField, "#")
-			if len(splited) != 2 {
-				return fmt.Errorf("It should be entered in the form of 'apiVersion:kind:namespace:name#fieldPath'")
-			}
 			key, ignoredPath := splited[0], splited[1]
 			ignoreConfig[key] = append(ignoreConfig[key], ignoredPath)
 		}

pkg/config/application.go

@@ -19,6 +19,7 @@ import (
 	"fmt"
 	"os"
 	"path/filepath"
+	"strings"
 
 	"github.com/pipe-cd/pipecd/pkg/model"
 )
@@ -649,6 +650,16 @@ type DriftDetection struct {
 	IgnoreFields []string `json:"ignoreFields"`
 }
 
+func (d *DriftDetection) Validate() error {
+	for _, ignoreField := range d.IgnoreFields {
+		splited := strings.Split(ignoreField, "#")
+		if len(splited) != 2 {
+			return fmt.Errorf("It should be entered in the form of 'apiVersion:kind:namespace:name#fieldPath'")
+		}
+	}
+	return nil
+}
+
 func LoadApplication(repoPath, configRelPath string, appKind model.ApplicationKind) (*GenericApplicationSpec, error) {
 	var absPath = filepath.Join(repoPath, configRelPath)