From 811b78c4e959e45ef093244ccee86217cbd97fda Mon Sep 17 00:00:00 2001
From: Olivier Michallat <olim7t@users.noreply.github.com>
Date: Fri, 15 Mar 2024 15:47:03 -0700
Subject: [PATCH] Reject cluster creation if a DC has an invalid name (fixes
 #1141)

---
 .../k8ssandra/v1alpha1/k8ssandracluster_webhook.go | 11 ++++++++++-
 .../v1alpha1/k8ssandracluster_webhook_test.go      | 14 ++++++++++++++
 2 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/apis/k8ssandra/v1alpha1/k8ssandracluster_webhook.go b/apis/k8ssandra/v1alpha1/k8ssandracluster_webhook.go
index 97e4b1b30..a0b0c2321 100644
--- a/apis/k8ssandra/v1alpha1/k8ssandracluster_webhook.go
+++ b/apis/k8ssandra/v1alpha1/k8ssandracluster_webhook.go
@@ -18,6 +18,8 @@ package v1alpha1
 
 import (
 	"fmt"
+	"k8s.io/apimachinery/pkg/util/validation"
+	"strings"
 
 	"github.com/Masterminds/semver/v3"
 	"github.com/k8ssandra/k8ssandra-operator/pkg/clientcache"
@@ -69,8 +71,15 @@ func (r *K8ssandraCluster) ValidateCreate() error {
 
 func (r *K8ssandraCluster) validateK8ssandraCluster() error {
 	hasClusterStorageConfig := r.Spec.Cassandra.DatacenterOptions.StorageConfig != nil
-	// Verify given k8s-contexts are correct
 	for _, dc := range r.Spec.Cassandra.Datacenters {
+		dns1035Errs := validation.IsDNS1035Label(dc.Meta.Name)
+		if len(dns1035Errs) > 0 {
+			return fmt.Errorf(
+				"invalid DC name (you might want to use datacenterName to override the name used in Cassandra): %s",
+				strings.Join(dns1035Errs, ", "))
+		}
+
+		// Verify given k8s-context is correct
 		_, err := clientCache.GetRemoteClient(dc.K8sContext)
 		if err != nil {
 			// No client found for this context name, reject
diff --git a/apis/k8ssandra/v1alpha1/k8ssandracluster_webhook_test.go b/apis/k8ssandra/v1alpha1/k8ssandracluster_webhook_test.go
index 1f86cce89..aed36c9ed 100644
--- a/apis/k8ssandra/v1alpha1/k8ssandracluster_webhook_test.go
+++ b/apis/k8ssandra/v1alpha1/k8ssandracluster_webhook_test.go
@@ -147,6 +147,7 @@ func TestWebhook(t *testing.T) {
 	t.Run("NumTokensValidationInUpdate", testNumTokensInUpdate)
 	t.Run("StsNameTooLong", testStsNameTooLong)
 	t.Run("MedusaPrefixMissing", testMedusaPrefixMissing)
+	t.Run("InvalidDcName", testInvalidDcName)
 }
 
 func testContextValidation(t *testing.T) {
@@ -219,6 +220,7 @@ func testStorageConfigValidation(t *testing.T) {
 	required.NoError(err)
 
 	cluster.Spec.Cassandra.Datacenters = append(cluster.Spec.Cassandra.Datacenters, CassandraDatacenterTemplate{
+		Meta:       EmbeddedObjectMeta{Name: "dc2"},
 		K8sContext: "envtest",
 		Size:       1,
 	})
@@ -376,6 +378,7 @@ func createClusterObjWithCassandraConfig(name, namespace string) *K8ssandraClust
 
 				Datacenters: []CassandraDatacenterTemplate{
 					{
+						Meta:       EmbeddedObjectMeta{Name: "dc1"},
 						K8sContext: "envtest",
 						Size:       1,
 					},
@@ -451,3 +454,14 @@ func testMedusaPrefixMissing(t *testing.T) {
 	err = k8sClient.Create(ctx, clusterWithPrefix)
 	required.NoError(err)
 }
+
+func testInvalidDcName(t *testing.T) {
+	required := require.New(t)
+	createNamespace(required, "ns")
+
+	clusterWithBadDcName := createMinimalClusterObj("bad-dc-name", "ns")
+	clusterWithBadDcName.Spec.Cassandra.Datacenters[0].Meta.Name = "DC1"
+	err := k8sClient.Create(ctx, clusterWithBadDcName)
+	required.Error(err)
+	required.Contains(err.Error(), "invalid DC name")
+}