Add flux create secret receiver command

Signed-off-by: Stefan Prodan <stefan.prodan@gmail.com>

internal/flags/receiver_type.go

@@ -0,0 +1,68 @@
+/*
+Copyright 2026 The Flux authors
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package flags
+
+import (
+	"fmt"
+	"strings"
+
+	notificationv1 "github.com/fluxcd/notification-controller/api/v1"
+
+	"github.com/fluxcd/flux2/v2/internal/utils"
+)
+
+var supportedReceiverTypes = []string{
+	notificationv1.GenericReceiver,
+	notificationv1.GenericHMACReceiver,
+	notificationv1.GitHubReceiver,
+	notificationv1.GitLabReceiver,
+	notificationv1.BitbucketReceiver,
+	notificationv1.HarborReceiver,
+	notificationv1.DockerHubReceiver,
+	notificationv1.QuayReceiver,
+	notificationv1.GCRReceiver,
+	notificationv1.NexusReceiver,
+	notificationv1.ACRReceiver,
+	notificationv1.CDEventsReceiver,
+}
+
+type ReceiverType string
+
+func (r *ReceiverType) String() string {
+	return string(*r)
+}
+
+func (r *ReceiverType) Set(str string) error {
+	if strings.TrimSpace(str) == "" {
+		return fmt.Errorf("no receiver type given, please specify %s",
+			r.Description())
+	}
+	if !utils.ContainsItemString(supportedReceiverTypes, str) {
+		return fmt.Errorf("receiver type '%s' is not supported, must be one of: %s",
+			str, strings.Join(supportedReceiverTypes, ", "))
+	}
+	*r = ReceiverType(str)
+	return nil
+}
+
+func (r *ReceiverType) Type() string {
+	return strings.Join(supportedReceiverTypes, "|")
+}
+
+func (r *ReceiverType) Description() string {
+	return "the receiver type"
+}