drivenets: create empty ConfigMap when config mount is defaulted

topo/node/drivenets/drivenets.go

@@ -641,7 +641,16 @@ func (n *Node) CreateConfig(ctx context.Context) (*corev1.Volume, error) {
 		data = v.Data
 	}
 	if data == nil {
-		return nil, nil
+		// No startup config was supplied. If the controller-managed Pod
+		// will nevertheless mount a config ConfigMap (because ConfigPath
+		// + ConfigFile are populated - typically by cdnosDefaults), we
+		// must still create an empty ConfigMap so the mount succeeds.
+		// Otherwise the Pod sits forever in PodInitializing with
+		// `configmap "<name>-config" not found`.
+		if pb.Config.GetConfigPath() == "" || pb.Config.GetConfigFile() == "" {
+			return nil, nil
+		}
+		data = []byte{}
 	}
 	cm := &corev1.ConfigMap{
 		ObjectMeta: metav1.ObjectMeta{

topo/node/drivenets/drivenets_test.go

@@ -1,11 +1,15 @@
 package drivenets
 
 import (
+	"context"
 	"testing"
 
 	"github.com/openconfig/gnmi/errdiff"
 	tpb "github.com/openconfig/kne/proto/topo"
 	"github.com/openconfig/kne/topo/node"
+	corev1 "k8s.io/api/core/v1"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/client-go/kubernetes/fake"
 )
 
 func TestNew(t *testing.T) {
@@ -108,6 +112,80 @@ func TestCdnosDefaults(t *testing.T) {
 	}
 }
 
+// TestCreateConfig_NoDataButPathDefaulted verifies that an empty ConfigMap
+// is still created when no startup data is supplied but cdnosDefaults has
+// populated ConfigPath/ConfigFile. Without this, the controller-created Pod
+// would block forever in PodInitializing on a missing ConfigMap mount.
+func TestCreateConfig_NoDataButPathDefaulted(t *testing.T) {
+	pb := cdnosDefaults(&tpb.Node{Name: "n1"})
+	if pb.Config.GetConfigPath() == "" || pb.Config.GetConfigFile() == "" {
+		t.Fatalf("preconditions: cdnosDefaults should populate ConfigPath and ConfigFile")
+	}
+	if pb.Config.GetConfigData() != nil {
+		t.Fatalf("preconditions: cdnosDefaults should not set startup config data")
+	}
+
+	kc := fake.NewSimpleClientset()
+	n := &Node{Impl: &node.Impl{
+		Proto:      pb,
+		KubeClient: kc,
+		Namespace:  "ns1",
+	}}
+
+	vol, err := n.CreateConfig(context.Background())
+	if err != nil {
+		t.Fatalf("CreateConfig returned unexpected error: %v", err)
+	}
+	if vol == nil {
+		t.Fatalf("CreateConfig returned nil volume; controller mount would fail")
+	}
+	cm, err := kc.CoreV1().ConfigMaps("ns1").Get(context.Background(), "n1-config", metav1.GetOptions{})
+	if err != nil {
+		t.Fatalf("expected ConfigMap n1-config to exist: %v", err)
+	}
+	if _, ok := cm.Data[pb.Config.GetConfigFile()]; !ok {
+		t.Errorf("ConfigMap missing key %q; have keys: %v", pb.Config.GetConfigFile(), keys(cm.Data))
+	}
+}
+
+// TestCreateConfig_NoDataAndNoPath verifies the explicit "no config mount"
+// path: when neither ConfigPath nor ConfigFile is set, no ConfigMap is
+// created.
+func TestCreateConfig_NoDataAndNoPath(t *testing.T) {
+	pb := &tpb.Node{
+		Name:   "n2",
+		Config: &tpb.Config{}, // empty: no Path, no File, no Data
+	}
+	kc := fake.NewSimpleClientset()
+	n := &Node{Impl: &node.Impl{
+		Proto:      pb,
+		KubeClient: kc,
+		Namespace:  "ns1",
+	}}
+	vol, err := n.CreateConfig(context.Background())
+	if err != nil {
+		t.Fatalf("CreateConfig returned unexpected error: %v", err)
+	}
+	if vol != nil {
+		t.Errorf("expected nil volume when no config is requested, got %+v", vol)
+	}
+	cms, _ := kc.CoreV1().ConfigMaps("ns1").List(context.Background(), metav1.ListOptions{})
+	if len(cms.Items) != 0 {
+		t.Errorf("expected zero ConfigMaps, found %d", len(cms.Items))
+	}
+}
+
+func keys(m map[string]string) []string {
+	out := make([]string, 0, len(m))
+	for k := range m {
+		out = append(out, k)
+	}
+	return out
+}
+
+// dummy var keeps corev1 imported even if the rest of the file doesn't use it.
+var _ = corev1.ConfigMap{}
+
 func TestDefaultNodeConstraints(t *testing.T) {
 	n := &Node{}
 	constraints := n.DefaultNodeConstraints()