OCPBUGS-84307: Clarify --base-domain flag default behavior

cmd/cluster/core/create.go

@@ -67,7 +67,7 @@ func BindOptions(opts *RawCreateOptions, flags *pflag.FlagSet) {
 func bindCoreOptions(opts *RawCreateOptions, flags *pflag.FlagSet) {
 	flags.StringVar(&opts.Namespace, "namespace", opts.Namespace, "A namespace to contain the generated resources")
 	flags.StringVar(&opts.Name, "name", opts.Name, "A name for the cluster")
-	flags.StringVar(&opts.BaseDomain, "base-domain", opts.BaseDomain, "The ingress base domain for the cluster")
+	flags.StringVar(&opts.BaseDomain, "base-domain", opts.BaseDomain, "The ingress base domain for the cluster. If omitted for an HCP KubeVirt cluster, this defaults to the management cluster's apps domain.")
 	flags.StringVar(&opts.BaseDomainPrefix, "base-domain-prefix", opts.BaseDomainPrefix, "The ingress base domain prefix for the cluster, defaults to cluster name. Use 'none' for an empty prefix")
 	flags.StringVar(&opts.ExternalDNSDomain, "external-dns-domain", opts.ExternalDNSDomain, "Sets hostname to opinionated values in the specified domain for services with publishing type LoadBalancer or Route.")
 	flags.StringVar(&opts.NetworkType, "network-type", opts.NetworkType, "Enum specifying the cluster SDN provider. Supports either Calico, OVNKubernetes, OpenShiftSDN or Other.")

cmd/cluster/core/create_test.go

@@ -23,8 +23,42 @@ import (
 
 	crclient "sigs.k8s.io/controller-runtime/pkg/client"
 	"sigs.k8s.io/controller-runtime/pkg/client/fake"
+
+	"github.com/spf13/pflag"
 )
 
+func TestBindOptions(t *testing.T) {
+	t.Run("When flags are parsed it should populate the options struct", func(t *testing.T) {
+		g := NewWithT(t)
+		opts := DefaultOptions()
+		flags := pflag.NewFlagSet("test", pflag.ContinueOnError)
+		BindOptions(opts, flags)
+
+		err := flags.Parse([]string{
+			"--base-domain=example.com",
+			"--name=my-cluster",
+			"--namespace=my-ns",
+		})
+
+		g.Expect(err).ToNot(HaveOccurred())
+		g.Expect(opts.BaseDomain).To(Equal("example.com"))
+		g.Expect(opts.Name).To(Equal("my-cluster"))
+		g.Expect(opts.Namespace).To(Equal("my-ns"))
+	})
+
+	t.Run("When base-domain flag is omitted the pflag default should be empty", func(t *testing.T) {
+		g := NewWithT(t)
+		opts := DefaultOptions()
+		flags := pflag.NewFlagSet("test", pflag.ContinueOnError)
+		BindOptions(opts, flags)
+
+		err := flags.Parse([]string{})
+
+		g.Expect(err).ToNot(HaveOccurred())
+		g.Expect(opts.BaseDomain).To(BeEmpty())
+	})
+}
+
 func TestValidateMgmtClusterAndNodePoolCPUArchitectures(t *testing.T) {
 	ctx := t.Context()