feat(template): add node count template function

api/pkg/template/cluster.go

@@ -0,0 +1,24 @@
+package template
+
+import (
+	"context"
+
+	corev1 "k8s.io/api/core/v1"
+)
+
+// nodeCount returns the total count of Kubernetes nodes in the cluster.
+// It returns 0 if the kubeClient is unavailable or if an error occurs.
+func (e *Engine) nodeCount() int {
+	logger := e.logger.WithField("function", "node-count")
+	if e.kubeClient == nil {
+		logger.Warn("kube client is nil, cannot get node count")
+		return 0
+	}
+	ctx := context.TODO()
+	nodeList := &corev1.NodeList{}
+	if err := e.kubeClient.List(ctx, nodeList); err != nil {
+		logger.WithError(err).Warn("failed to list nodes")
+		return 0
+	}
+	return len(nodeList.Items)
+}

api/pkg/template/cluster_test.go

@@ -0,0 +1,133 @@
+package template
+
+import (
+	"context"
+	"fmt"
+	"testing"
+
+	kotsv1beta1 "github.com/replicatedhq/kotskinds/apis/kots/v1beta1"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	corev1 "k8s.io/api/core/v1"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/runtime"
+	"k8s.io/client-go/kubernetes/scheme"
+	"sigs.k8s.io/controller-runtime/pkg/client"
+	clientfake "sigs.k8s.io/controller-runtime/pkg/client/fake"
+	"sigs.k8s.io/controller-runtime/pkg/client/interceptor"
+)
+
+func TestEngine_NodeCount(t *testing.T) {
+	config := &kotsv1beta1.Config{
+		Spec: kotsv1beta1.ConfigSpec{
+			Groups: []kotsv1beta1.ConfigGroup{},
+		},
+	}
+
+	t.Run("returns 0 when kubeClient is nil", func(t *testing.T) {
+		engine := NewEngine(config)
+
+		err := engine.Parse("{{repl NodeCount }}")
+		require.NoError(t, err)
+		result, err := engine.Execute(nil)
+		require.NoError(t, err)
+		assert.Equal(t, "0", result)
+	})
+
+	t.Run("returns correct count with multiple nodes", func(t *testing.T) {
+		// Set up scheme for fake client
+		sch := runtime.NewScheme()
+		require.NoError(t, corev1.AddToScheme(sch))
+		require.NoError(t, scheme.AddToScheme(sch))
+
+		// Create fake nodes
+		node1 := &corev1.Node{
+			ObjectMeta: metav1.ObjectMeta{
+				Name: "node-1",
+			},
+		}
+		node2 := &corev1.Node{
+			ObjectMeta: metav1.ObjectMeta{
+				Name: "node-2",
+			},
+		}
+		node3 := &corev1.Node{
+			ObjectMeta: metav1.ObjectMeta{
+				Name: "node-3",
+			},
+		}
+
+		// Create fake client with nodes
+		fakeClient := clientfake.NewClientBuilder().
+			WithScheme(sch).
+			WithObjects(node1, node2, node3).
+			Build()
+
+		engine := NewEngine(config, WithKubeClient(fakeClient))
+
+		err := engine.Parse("{{repl NodeCount }}")
+		require.NoError(t, err)
+		result, err := engine.Execute(nil)
+		require.NoError(t, err)
+		assert.Equal(t, "3", result)
+	})
+
+	t.Run("can be used in conditional expressions", func(t *testing.T) {
+		// Set up scheme for fake client
+		sch := runtime.NewScheme()
+		require.NoError(t, corev1.AddToScheme(sch))
+		require.NoError(t, scheme.AddToScheme(sch))
+
+		// Create fake nodes
+		node1 := &corev1.Node{
+			ObjectMeta: metav1.ObjectMeta{
+				Name: "node-1",
+			},
+		}
+		node2 := &corev1.Node{
+			ObjectMeta: metav1.ObjectMeta{
+				Name: "node-2",
+			},
+		}
+
+		// Create fake client with nodes
+		fakeClient := clientfake.NewClientBuilder().
+			WithScheme(sch).
+			WithObjects(node1, node2).
+			Build()
+
+		engine := NewEngine(config, WithKubeClient(fakeClient))
+
+		// Test conditional expression
+		err := engine.Parse("{{repl if gt (NodeCount) 1 }}HA{{repl else }}Standalone{{repl end }}")
+		require.NoError(t, err)
+		result, err := engine.Execute(nil)
+		require.NoError(t, err)
+		assert.Equal(t, "HA", result)
+	})
+
+	t.Run("returns 0 when kubeClient List returns error", func(t *testing.T) {
+		// Set up scheme for fake client
+		sch := runtime.NewScheme()
+		require.NoError(t, corev1.AddToScheme(sch))
+		require.NoError(t, scheme.AddToScheme(sch))
+
+		// Create fake client with interceptor that returns error on List
+		fakeClient := clientfake.NewClientBuilder().
+			WithScheme(sch).
+			WithInterceptorFuncs(interceptor.Funcs{
+				List: func(ctx context.Context, client client.WithWatch, list client.ObjectList, opts ...client.ListOption) error {
+					return fmt.Errorf("simulated list error")
+				},
+			}).
+			Build()
+
+		engine := NewEngine(config, WithKubeClient(fakeClient))
+
+		err := engine.Parse("{{repl NodeCount }}")
+		require.NoError(t, err)
+		result, err := engine.Execute(nil)
+		require.NoError(t, err)
+		assert.Equal(t, "0", result)
+	})
+}

api/pkg/template/execute.go

@@ -194,6 +194,9 @@ func (e *Engine) getFuncMap() template.FuncMap {
 
 		// App template functions
 		"Namespace": e.namespace,
+
+		// Cluster template functions
+		"NodeCount": e.nodeCount,
 	}
 }