From 4e2ccd12bef5de6e88b3c57fba784e53430aa28b Mon Sep 17 00:00:00 2001
From: Martin Weindel <martin.weindel@sap.com>
Date: Wed, 15 Jan 2025 17:20:09 +0100
Subject: [PATCH] add loadtest tool

---
 hack/tools/loadtest/main.go | 122 ++++++++++++++++++++++++++++++++++++
 1 file changed, 122 insertions(+)
 create mode 100644 hack/tools/loadtest/main.go

diff --git a/hack/tools/loadtest/main.go b/hack/tools/loadtest/main.go
new file mode 100644
index 00000000..3e3f06cf
--- /dev/null
+++ b/hack/tools/loadtest/main.go
@@ -0,0 +1,122 @@
+// SPDX-FileCopyrightText: SAP SE or an SAP affiliate company and Gardener contributors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//
+// This small tool can be used to create a given number of DNS entries for load tests:
+//
+// Usage:
+//	go run main.go
+//
+//  Command line options:
+//     -base-domain string
+//     		base domain for the entries (mandatory)
+//     -count int
+//     		number of entries to create (default 10)
+//     -kubeconfig string
+//     		absolute path to the kubeconfig file (defaults to the env variable `KUBECONFIG`)
+//     -label string
+//     		label value for label 'loadtest' to set on the entries (default "true")
+//
+// You may use `kubectl delete dnsentry -l loadtest=<label-value>` to delete them all at once.
+
+package main
+
+import (
+	"context"
+	"flag"
+	"fmt"
+	"os"
+
+	dnsv1alpha1 "github.com/gardener/external-dns-management/pkg/apis/dns/v1alpha1"
+	dnsmanclient "github.com/gardener/external-dns-management/pkg/dnsman2/client"
+	"github.com/gardener/gardener/pkg/controllerutils"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/client-go/tools/clientcmd"
+	"k8s.io/utils/ptr"
+	"sigs.k8s.io/controller-runtime/pkg/client"
+)
+
+var (
+	kubeconfig string
+	baseDomain string
+	labelValue string
+	count      int
+)
+
+func main() {
+	flag.StringVar(&kubeconfig, "kubeconfig", os.Getenv("KUBECONFIG"), "absolute path to the kubeconfig file")
+	flag.IntVar(&count, "count", 10, "number of entries to create")
+	flag.StringVar(&baseDomain, "base-domain", "", "base domain for the entries")
+	flag.StringVar(&labelValue, "label", "true", "label value for label 'loadtest' to set on the entries")
+	flag.Parse()
+
+	if baseDomain == "" {
+		fmt.Fprintf(os.Stderr, "-base-domain is required\n")
+		os.Exit(1)
+	}
+
+	c, err := createClient()
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "failed to create client: %w\n", err)
+		os.Exit(1)
+	}
+
+	ctx := context.Background()
+
+	fmt.Fprintf(os.Stdout, "Creating %d entries created - please wait\n", count)
+
+	if err := createEntries(ctx, c, count, "e%05d", baseDomain, "loadtest", labelValue); err != nil {
+		fmt.Fprintf(os.Stderr, "failed to create entries: %w\n", err)
+		os.Exit(2)
+	}
+
+	fmt.Fprintf(os.Stdout, "Done - all %d entries created\n", count)
+}
+
+func createEntries(ctx context.Context, c client.Client, count int, nameTemplate, baseDomain, labelKey, labelValue string) error {
+	for i := 0; i < count; i++ {
+		entry := &dnsv1alpha1.DNSEntry{
+			ObjectMeta: metav1.ObjectMeta{
+				Namespace: "default",
+				Name:      fmt.Sprintf(nameTemplate, i),
+			},
+		}
+		if _, err := controllerutils.CreateOrGetAndMergePatch(ctx, c, entry, func() error {
+			entry.Labels = map[string]string{
+				labelKey: labelValue,
+			}
+			entry.Spec = dnsv1alpha1.DNSEntrySpec{
+				DNSName: fmt.Sprintf("%s.%s", fmt.Sprintf(nameTemplate, i), baseDomain),
+				Targets: []string{fmt.Sprintf("2.%d.%d.%d", i>>16, (i&0xff00)>>8, i&0xff)},
+				TTL:     ptr.To[int64](120),
+			}
+			return nil
+		}); err != nil {
+			return fmt.Errorf("failed to create/update entry %s: %w", entry.Name, err)
+		}
+		if i > 0 && i%100 == 0 {
+			fmt.Fprintf(os.Stdout, "%d/%d entries created...\n", i, count)
+		}
+	}
+
+	return nil
+}
+
+func createClient() (client.Client, error) {
+	if kubeconfig == "" {
+		return nil, fmt.Errorf("-kubeconfig or KUBECONFIG env var is required")
+	}
+
+	cfg, err := clientcmd.LoadFromFile(kubeconfig)
+	if err != nil {
+		return nil, err
+	}
+	clientConfig := clientcmd.NewDefaultClientConfig(*cfg, &clientcmd.ConfigOverrides{})
+	restConfig, err := clientConfig.ClientConfig()
+	if err != nil {
+		return nil, err
+	}
+
+	return client.New(restConfig, client.Options{Scheme: dnsmanclient.ClusterScheme})
+}