Prefix generated username with 'default_user_'

- it will make it easier to specify exclusion rules when
using schema sync plugin

internal/resource/default_user_secret.go

@@ -29,6 +29,7 @@ const (
 	DefaultUserSecretName = "default-user"
 	bindingProvider       = "rabbitmq"
 	bindingType           = "rabbitmq"
+	usernamePrefix        = "default_user_"
 )
 
 type DefaultUserSecretBuilder struct {
@@ -40,7 +41,7 @@ func (builder *RabbitmqResourceBuilder) DefaultUserSecret() *DefaultUserSecretBu
 }
 
 func (builder *DefaultUserSecretBuilder) Build() (client.Object, error) {
-	username, err := randomEncodedString(24)
+	username, err := generateUsername(24)
 	if err != nil {
 		return nil, err
 	}
@@ -146,6 +147,18 @@ func (builder *DefaultUserSecretBuilder) updatePorts(secret *corev1.Secret) {
 	}
 }
 
+// generateUsername returns a base64 string that has "default_user_" as prefix
+// returned string has length 'l' when base64 decoded
+func generateUsername(l int) (string, error) {
+	encodedStr, err := randomEncodedString(l)
+	if err != nil {
+		return "", err
+	}
+
+	encodedStrSlice := []byte(encodedStr)
+	return string(append([]byte(usernamePrefix), encodedStrSlice[0:len(encodedStrSlice)-len(usernamePrefix)]...)), nil
+}
+
 func (builder *DefaultUserSecretBuilder) pluginEnabled(plugin v1beta1.Plugin) bool {
 	for _, value := range builder.Instance.Spec.Rabbitmq.AdditionalPlugins {
 		if value == plugin {

internal/resource/default_user_secret_test.go

@@ -11,18 +11,16 @@ package resource_test
 
 import (
 	b64 "encoding/base64"
-
-	"gopkg.in/ini.v1"
-	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
-	v1 "k8s.io/apimachinery/pkg/apis/meta/v1"
-	"k8s.io/apimachinery/pkg/runtime"
-	defaultscheme "k8s.io/client-go/kubernetes/scheme"
-
 	. "github.com/onsi/ginkgo"
 	. "github.com/onsi/gomega"
 	rabbitmqv1beta1 "github.com/rabbitmq/cluster-operator/api/v1beta1"
 	"github.com/rabbitmq/cluster-operator/internal/resource"
+	"gopkg.in/ini.v1"
 	corev1 "k8s.io/api/core/v1"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	v1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/runtime"
+	defaultscheme "k8s.io/client-go/kubernetes/scheme"
 )
 
 var _ = Describe("DefaultUserSecret", func() {
@@ -72,15 +70,17 @@ var _ = Describe("DefaultUserSecret", func() {
 				Expect(secret.Type).To(Equal(corev1.SecretTypeOpaque))
 			})
 
-			By("creating a rabbitmq username that is base64 encoded and 24 characters in length", func() {
+			By("creating a rabbitmq username that has a prefix 'default_user_', base64 encoded, and 24 characters in length when decoded", func() {
 				username, ok = secret.Data["username"]
 				Expect(ok).NotTo(BeFalse(), "Failed to find a key \"username\" in the generated Secret")
-				decodedUsername, err := b64.URLEncoding.DecodeString(string(username))
+				Expect(string(username)).To(HavePrefix("default_user_"))
+				//strList := strings.SplitAfter(string(username), "default_user_")
+				decoded, err := b64.URLEncoding.DecodeString(string(username))
 				Expect(err).NotTo(HaveOccurred())
-				Expect(len(decodedUsername)).To(Equal(24))
+				Expect(len(decoded)).To(Equal(24))
 			})
 
-			By("creating a rabbitmq password that is base64 encoded and 24 characters in length", func() {
+			By("creating a rabbitmq password that is base64 encoded and 24 characters in length when decoded", func() {
 				password, ok = secret.Data["password"]
 				Expect(ok).NotTo(BeFalse(), "Failed to find a key \"password\" in the generated Secret")
 				decodedPassword, err := b64.URLEncoding.DecodeString(string(password))