add tests for kubernetes versions (#7035)

cmd/nginx-ingress/main.go

@@ -92,7 +92,9 @@ func main() {
 	podName := os.Getenv("POD_NAME")
 
 	config, kubeClient := mustCreateConfigAndKubeClient(ctx)
-	mustValidateKubernetesVersionInfo(ctx, kubeClient)
+	if err := validateKubernetesVersionInfo(ctx, kubeClient); err != nil {
+		nl.Fatal(l, err)
+	}
 	pod, err := kubeClient.CoreV1().Pods(controllerNamespace).Get(context.TODO(), podName, meta_v1.GetOptions{})
 	if err != nil {
 		nl.Fatalf(l, "Failed to get pod: %v", err)
@@ -399,24 +401,25 @@ func mustCreateConfigAndKubeClient(ctx context.Context) (*rest.Config, *kubernet
 	return config, kubeClient
 }
 
-// mustValidateKubernetesVersionInfo calls internally os.Exit if
+// validateKubernetesVersionInfo returns an Error if
 // the k8s version can not be retrieved or the version is not supported.
-func mustValidateKubernetesVersionInfo(ctx context.Context, kubeClient kubernetes.Interface) {
+func validateKubernetesVersionInfo(ctx context.Context, kubeClient kubernetes.Interface) error {
 	l := nl.LoggerFromContext(ctx)
 	k8sVersion, err := k8s.GetK8sVersion(kubeClient)
 	if err != nil {
-		nl.Fatalf(l, "error retrieving k8s version: %v", err)
+		return fmt.Errorf("error retrieving k8s version: %w", err)
 	}
 	nl.Infof(l, "Kubernetes version: %v", k8sVersion)
 
 	minK8sVersion, err := util_version.ParseGeneric("1.22.0")
 	if err != nil {
-		nl.Fatalf(l, "unexpected error parsing minimum supported version: %v", err)
+		return fmt.Errorf("unexpected error parsing minimum supported version: %w", err)
 	}
 
 	if !k8sVersion.AtLeast(minK8sVersion) {
-		nl.Fatalf(l, "Versions of Kubernetes < %v are not supported, please refer to the documentation for details on supported versions and legacy controller support.", minK8sVersion)
+		return fmt.Errorf("versions of kubernetes < %v are not supported, please refer to the documentation for details on supported versions and legacy controller support", minK8sVersion)
 	}
+	return nil
 }
 
 // mustValidateIngressClass calls internally os.Exit

cmd/nginx-ingress/main_test.go

@@ -2,11 +2,18 @@ package main
 
 import (
 	"bytes"
+	"context"
+	"io"
+	"log/slog"
 	"regexp"
 	"testing"
 
 	nl "github.com/nginxinc/kubernetes-ingress/internal/logger"
+	nic_glog "github.com/nginxinc/kubernetes-ingress/internal/logger/glog"
 	"github.com/nginxinc/kubernetes-ingress/internal/logger/levels"
+	pkgversion "k8s.io/apimachinery/pkg/version"
+	fakediscovery "k8s.io/client-go/discovery/fake"
+	"k8s.io/client-go/kubernetes/fake"
 )
 
 func TestLogFormats(t *testing.T) {
@@ -46,3 +53,81 @@ func TestLogFormats(t *testing.T) {
 		})
 	}
 }
+
+func TestK8sVersionValidation(t *testing.T) {
+	testCases := []struct {
+		name        string
+		kubeVersion string
+	}{
+		{
+			name:        "Earliest version 1.22.0",
+			kubeVersion: "1.22.0",
+		},
+		{
+			name:        "Minor version 1.22.5",
+			kubeVersion: "1.22.5",
+		},
+		{
+			name:        "Close to current 1.32.0",
+			kubeVersion: "1.32.0",
+		},
+	}
+	t.Parallel()
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			// setup logger
+			l := slog.New(nic_glog.New(io.Discard, &nic_glog.Options{Level: levels.LevelInfo}))
+			ctx := nl.ContextWithLogger(context.Background(), l)
+
+			// setup kube client with version
+			clientset := fake.NewSimpleClientset()
+			fakeDiscovery, _ := clientset.Discovery().(*fakediscovery.FakeDiscovery)
+			fakeDiscovery.FakedServerVersion = &pkgversion.Info{GitVersion: tc.kubeVersion}
+
+			// run test
+			err := validateKubernetesVersionInfo(ctx, clientset)
+			if err != nil {
+				t.Errorf("%v", err)
+			}
+		})
+	}
+}
+
+func TestK8sVersionValidationBad(t *testing.T) {
+	testCases := []struct {
+		name        string
+		kubeVersion string
+	}{
+		{
+			name:        "Before earliest version 1.21.0",
+			kubeVersion: "1.21.0",
+		},
+		{
+			name:        "Empty version",
+			kubeVersion: "",
+		},
+		{
+			name:        "Garbage",
+			kubeVersion: "xyzabc",
+		},
+	}
+	t.Parallel()
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			// setup logger
+			l := slog.New(nic_glog.New(io.Discard, &nic_glog.Options{Level: levels.LevelInfo}))
+			ctx := nl.ContextWithLogger(context.Background(), l)
+
+			// setup kube client with version
+			clientset := fake.NewSimpleClientset()
+			fakeDiscovery, _ := clientset.Discovery().(*fakediscovery.FakeDiscovery)
+			fakeDiscovery.FakedServerVersion = &pkgversion.Info{GitVersion: tc.kubeVersion}
+
+			// run test
+			err := validateKubernetesVersionInfo(ctx, clientset)
+			if err == nil {
+				t.Error("Wanted an error here")
+			}
+		})
+	}
+}