fix(#3393): Make CronJob functionality optional

- Explicitly check for CronJob batch/v1 API availability before using it
- CronJob batch/v1 API is not available on OpenShift 3.x
- Disable cron job e2e test on OpenShift 3.x

e2e/common/cli/install_test.go

@@ -38,7 +38,7 @@ import (
 	"github.com/apache/camel-k/pkg/util/defaults"
 	"github.com/apache/camel-k/pkg/util/kubernetes"
 	"github.com/apache/camel-k/pkg/util/openshift"
-	console "github.com/openshift/api/console/v1"
+	consolev1 "github.com/openshift/api/console/v1"
 	corev1 "k8s.io/api/core/v1"
 )
 
@@ -98,11 +98,11 @@ func TestConsoleCliDownload(t *testing.T) {
 	ocp, err := openshift.IsOpenShift(TestClient())
 	assert.Nil(t, err)
 
-	ok, err := kubernetes.IsAPIResourceInstalled(TestClient(), "console.openshift.io/v1", reflect.TypeOf(console.ConsoleCLIDownload{}).Name())
+	ok, err := kubernetes.IsAPIResourceInstalled(TestClient(), "console.openshift.io/v1", reflect.TypeOf(consolev1.ConsoleCLIDownload{}).Name())
 	assert.Nil(t, err)
 
 	if !ocp || !ok {
-		t.Skip("This test requires ConsoleCliDownload object which is available on OpenShift 4 only.")
+		t.Skip("This test requires ConsoleCliDownload object which is available on OpenShift 4+ only.")
 		return
 	}
 

e2e/common/cron_test.go

@@ -23,17 +23,29 @@ limitations under the License.
 package common
 
 import (
+	"reflect"
 	"testing"
 
 	. "github.com/onsi/gomega"
+	"github.com/stretchr/testify/assert"
 
+	batchv1 "k8s.io/api/batch/v1"
 	corev1 "k8s.io/api/core/v1"
 
 	. "github.com/apache/camel-k/e2e/support"
 	v1 "github.com/apache/camel-k/pkg/apis/camel/v1"
+	"github.com/apache/camel-k/pkg/util/kubernetes"
 )
 
 func TestRunCronExample(t *testing.T) {
+	ok, err := kubernetes.IsAPIResourceInstalled(TestClient(), batchv1.SchemeGroupVersion.Group, reflect.TypeOf(batchv1.CronJob{}).Name())
+	assert.Nil(t, err)
+
+	if !ok {
+		t.Skip("This test requires CronJob batch/v1 API installed.")
+		return
+	}
+
 	WithNewTestNamespace(t, func(ns string) {
 		Expect(Kamel("install", "-n", ns).Execute()).To(Succeed())
 

pkg/cmd/operator/operator.go

@@ -23,6 +23,7 @@ import (
 	"fmt"
 	"math/rand"
 	"os"
+	"reflect"
 	"runtime"
 	"strconv"
 	"strings"
@@ -35,6 +36,7 @@ import (
 	coordination "k8s.io/api/coordination/v1"
 	corev1 "k8s.io/api/core/v1"
 	k8serrors "k8s.io/apimachinery/pkg/api/errors"
+	"k8s.io/apimachinery/pkg/fields"
 	"k8s.io/apimachinery/pkg/labels"
 	"k8s.io/apimachinery/pkg/selection"
 	"k8s.io/client-go/tools/leaderelection/resourcelock"
@@ -192,6 +194,22 @@ func Run(healthPort, monitoringPort int32, leaderElection bool, leaderElectionID
 	exitOnError(err, "cannot create Integration label selector")
 	selector := labels.NewSelector().Add(*hasIntegrationLabel)
 
+	selectors := cache.SelectorsByObject{
+		&corev1.Pod{}:        {Label: selector},
+		&appsv1.Deployment{}: {Label: selector},
+		&batchv1.Job{}:       {Label: selector},
+		&servingv1.Service{}: {Label: selector},
+	}
+
+	if ok, err := kubernetes.IsAPIResourceInstalled(c, batchv1.SchemeGroupVersion.String(), reflect.TypeOf(batchv1.CronJob{}).Name()); ok && err == nil {
+		selectors[&batchv1.CronJob{}] = struct {
+			Label labels.Selector
+			Field fields.Selector
+		}{
+			Label: selector,
+		}
+	}
+
 	mgr, err := manager.New(c.GetConfig(), manager.Options{
 		Namespace:                     watchNamespace,
 		EventBroadcaster:              broadcaster,
@@ -204,13 +222,7 @@ func Run(healthPort, monitoringPort int32, leaderElection bool, leaderElectionID
 		MetricsBindAddress:            ":" + strconv.Itoa(int(monitoringPort)),
 		NewCache: cache.BuilderWithOptions(
 			cache.Options{
-				SelectorsByObject: cache.SelectorsByObject{
-					&corev1.Pod{}:        {Label: selector},
-					&appsv1.Deployment{}: {Label: selector},
-					&batchv1.CronJob{}:   {Label: selector},
-					&batchv1.Job{}:       {Label: selector},
-					&servingv1.Service{}: {Label: selector},
-				},
+				SelectorsByObject: selectors,
 			},
 		),
 	})

pkg/controller/integration/integration_controller.go

@@ -205,8 +205,6 @@ func add(mgr manager.Manager, c client.Client, r reconcile.Reconciler) error {
 			})).
 		// Watch for the owned Deployments
 		Owns(&appsv1.Deployment{}, builder.WithPredicates(StatusChangedPredicate{})).
-		// Watch for the owned CronJobs
-		Owns(&batchv1.CronJob{}, builder.WithPredicates(StatusChangedPredicate{})).
 		// Watch for the Integration Pods
 		Watches(&source.Kind{Type: &corev1.Pod{}},
 			handler.EnqueueRequestsFromMapFunc(func(a ctrl.Object) []reconcile.Request {
@@ -225,6 +223,11 @@ func add(mgr manager.Manager, c client.Client, r reconcile.Reconciler) error {
 				}
 			}))
 
+	if ok, err := kubernetes.IsAPIResourceInstalled(c, batchv1.SchemeGroupVersion.String(), reflect.TypeOf(batchv1.CronJob{}).Name()); ok && err == nil {
+		// Watch for the owned CronJobs
+		b.Owns(&batchv1.CronJob{}, builder.WithPredicates(StatusChangedPredicate{}))
+	}
+
 	// Watch for the owned Knative Services conditionally
 	if ok, err := kubernetes.IsAPIResourceInstalled(c, servingv1.SchemeGroupVersion.String(), reflect.TypeOf(servingv1.Service{}).Name()); err != nil {
 		return err