use crypto/rand instead of math/rand

pkg/controller/model/utils.go

@@ -1,17 +1,22 @@
 package model
 
 import (
-	"math/rand"
+	"crypto/rand"
+	"encoding/base64"
 )
 
-var letterRunes = []rune("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ")
-
-func RandStringRunes(n int) string {
-	b := make([]rune, n)
-	for i := range b {
-		b[i] = letterRunes[rand.Intn(len(letterRunes))]
+func generateRandomBytes(n int) []byte {
+	b := make([]byte, n)
+	_, err := rand.Read(b)
+	if err != nil {
+		panic(err)
 	}
-	return string(b)
+	return b
+}
+
+func RandStringRunes(s int) string {
+	b := generateRandomBytes(s)
+	return base64.URLEncoding.EncodeToString(b)
 }
 
 func MergeAnnotations(requested map[string]string, existing map[string]string) map[string]string {