fix config checker to support yaml tag flow (#716)

pkgconfig/config.go

@@ -4,6 +4,7 @@ import (
 	"io"
 	"os"
 	"reflect"
+	"strings"
 
 	"github.com/pkg/errors"
 	"gopkg.in/yaml.v3"
@@ -112,12 +113,16 @@ func CheckConfigWithTags(v reflect.Value, userCfg map[string]interface{}) error
 		for i := 0; i < v.NumField(); i++ {
 			fieldValue := v.Field(i)
 			fieldType := t.Field(i)
+
+			// get name from yaml tag
 			fieldTag := fieldType.Tag.Get("yaml")
+			tagClean := strings.TrimSuffix(fieldTag, ",flow")
 
-			if fieldTag == k {
+			// compare
+			if tagClean == k {
 				keyExist = true
 			}
-			if fieldValue.Kind() == reflect.Struct && fieldTag == k {
+			if fieldValue.Kind() == reflect.Struct && tagClean == k {
 				if kvMap, ok := kv.(map[string]interface{}); ok {
 					err := CheckConfigWithTags(fieldValue, kvMap)
 					if err != nil {

pkgconfig/config_test.go

@@ -232,6 +232,20 @@ multiplexer:
   routes:
   - from: [ tap ]
     to: [ scalyr ]
+`,
+			wantErr: false,
+		},
+		{
+			name: "Valid tranforms key with flow argument",
+			content: `
+multiplexer:
+  collectors:
+  - name: tap
+    dnstap:
+      listen-ip: 0.0.0.0
+    transforms:
+      atags:
+        tags: [ "TXT:google", "MX:apple" ]
 `,
 			wantErr: false,
 		},