Add --for=create option to kubectl wait

Author: soltysh

staging/src/k8s.io/kubectl/pkg/cmd/wait/create.go

@@ -0,0 +1,33 @@
+/*
+Copyright 2024 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package wait
+
+import (
+	"context"
+	"fmt"
+
+	"k8s.io/apimachinery/pkg/runtime"
+	"k8s.io/cli-runtime/pkg/resource"
+)
+
+// IsCreated is a condition func for waiting for something to be created
+func IsCreated(ctx context.Context, info *resource.Info, o *WaitOptions) (runtime.Object, bool, error) {
+	if len(info.Name) == 0 || info.Object == nil {
+		return nil, false, fmt.Errorf("resource name must be provided")
+	}
+	return info.Object, true, nil
+}

staging/src/k8s.io/kubectl/pkg/cmd/wait/wait.go

@@ -30,6 +30,7 @@ import (
 	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/runtime/schema"
 	"k8s.io/apimachinery/pkg/types"
+	"k8s.io/apimachinery/pkg/util/wait"
 	"k8s.io/cli-runtime/pkg/genericclioptions"
 	"k8s.io/cli-runtime/pkg/genericiooptions"
 	"k8s.io/cli-runtime/pkg/printers"
@@ -186,11 +187,16 @@ func (flags *WaitFlags) ToOptions(args []string) (*WaitOptions, error) {
 }
 
 func conditionFuncFor(condition string, errOut io.Writer) (ConditionFunc, error) {
-	if strings.ToLower(condition) == "delete" {
+	lowercaseCond := strings.ToLower(condition)
+	switch {
+	case lowercaseCond == "delete":
 		return IsDeleted, nil
-	}
-	if strings.HasPrefix(condition, "condition=") {
-		conditionName := condition[len("condition="):]
+
+	case lowercaseCond == "create":
+		return IsCreated, nil
+
+	case strings.HasPrefix(lowercaseCond, "condition="):
+		conditionName := lowercaseCond[len("condition="):]
 		conditionValue := "true"
 		if equalsIndex := strings.Index(conditionName, "="); equalsIndex != -1 {
 			conditionValue = conditionName[equalsIndex+1:]
@@ -202,9 +208,9 @@ func conditionFuncFor(condition string, errOut io.Writer) (ConditionFunc, error)
 			conditionStatus: conditionValue,
 			errOut:          errOut,
 		}.IsConditionMet, nil
-	}
-	if strings.HasPrefix(condition, "jsonpath=") {
-		jsonPathInput := strings.TrimPrefix(condition, "jsonpath=")
+
+	case strings.HasPrefix(lowercaseCond, "jsonpath="):
+		jsonPathInput := strings.TrimPrefix(lowercaseCond, "jsonpath=")
 		jsonPathExp, jsonPathValue, err := processJSONPathInput(jsonPathInput)
 		if err != nil {
 			return nil, err
@@ -312,6 +318,31 @@ func (o *WaitOptions) RunWait() error {
 	ctx, cancel := watchtools.ContextWithOptionalTimeout(context.Background(), o.Timeout)
 	defer cancel()
 
+	if strings.ToLower(o.ForCondition) == "create" {
+		// TODO(soltysh): this is not ideal solution, because we're polling every .5s,
+		// and we have to use ResourceFinder, which contains the resource name.
+		// In the long run, we should expose resource information from ResourceFinder,
+		// or functions from ResourceBuilder for parsing those. Lastly, this poll
+		// should be replaced with a ListWatch cache.
+		if err := wait.PollUntilContextTimeout(ctx, 500*time.Millisecond, o.Timeout, true, func(context.Context) (done bool, err error) {
+			visitErr := o.ResourceFinder.Do().Visit(func(info *resource.Info, err error) error {
+				return nil
+			})
+			if apierrors.IsNotFound(visitErr) {
+				return false, nil
+			}
+			if visitErr != nil {
+				return false, visitErr
+			}
+			return true, nil
+		}); err != nil {
+			if errors.Is(err, context.DeadlineExceeded) {
+				return fmt.Errorf("%s", wait.ErrWaitTimeout.Error()) // nolint:staticcheck // SA1019
+			}
+			return err
+		}
+	}
+
 	visitCount := 0
 	visitFunc := func(info *resource.Info, err error) error {
 		if err != nil {

staging/src/k8s.io/kubectl/pkg/cmd/wait/wait_test.go

@@ -24,6 +24,8 @@ import (
 
 	"github.com/stretchr/testify/require"
 
+	corev1 "k8s.io/api/core/v1"
+	apierrors "k8s.io/apimachinery/pkg/api/errors"
 	"k8s.io/apimachinery/pkg/api/meta"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
@@ -76,7 +78,7 @@ spec:
           memory: 128Mi
         requests:
           cpu: 250m
-          memory: 64Mi  
+          memory: 64Mi
       terminationMessagePath: /dev/termination-log
       terminationMessagePolicy: File
       volumeMounts:
@@ -983,6 +985,77 @@ func TestWaitForCondition(t *testing.T) {
 	}
 }
 
+func TestWaitForCreate(t *testing.T) {
+	scheme := runtime.NewScheme()
+	listMapping := map[schema.GroupVersionResource]string{
+		{Group: "group", Version: "version", Resource: "theresource"}: "TheKindList",
+	}
+
+	tests := []struct {
+		name       string
+		infos      []*resource.Info
+		infosErr   error
+		fakeClient func() *dynamicfakeclient.FakeDynamicClient
+		timeout    time.Duration
+
+		expectedErr string
+	}{
+		{
+			name:     "missing resource, should hit timeout",
+			infosErr: apierrors.NewNotFound(schema.GroupResource{Group: "group", Resource: "theresource"}, "name-foo"),
+			fakeClient: func() *dynamicfakeclient.FakeDynamicClient {
+				return dynamicfakeclient.NewSimpleDynamicClientWithCustomListKinds(scheme, listMapping)
+			},
+			timeout:     1 * time.Second,
+			expectedErr: "timed out waiting for the condition",
+		},
+		{
+			name: "wait should succeed",
+			infos: []*resource.Info{
+				{
+					Mapping: &meta.RESTMapping{
+						Resource: schema.GroupVersionResource{Group: "group", Version: "version", Resource: "theresource"},
+					},
+					Object:    &corev1.Pod{}, // the resource type is irrelevant here
+					Name:      "name-foo",
+					Namespace: "ns-foo",
+				},
+			},
+			fakeClient: func() *dynamicfakeclient.FakeDynamicClient {
+				return dynamicfakeclient.NewSimpleDynamicClientWithCustomListKinds(scheme, listMapping)
+			},
+			timeout: 1 * time.Second,
+		},
+	}
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			fakeClient := test.fakeClient()
+			o := &WaitOptions{
+				ResourceFinder: genericclioptions.NewSimpleFakeResourceFinder(test.infos...).WithError(test.infosErr),
+				DynamicClient:  fakeClient,
+				Timeout:        test.timeout,
+
+				Printer:      printers.NewDiscardingPrinter(),
+				ConditionFn:  IsCreated,
+				ForCondition: "create",
+				IOStreams:    genericiooptions.NewTestIOStreamsDiscard(),
+			}
+			err := o.RunWait()
+			switch {
+			case err == nil && len(test.expectedErr) == 0:
+			case err != nil && len(test.expectedErr) == 0:
+				t.Fatal(err)
+			case err == nil && len(test.expectedErr) != 0:
+				t.Fatalf("missing: %q", test.expectedErr)
+			case err != nil && len(test.expectedErr) != 0:
+				if !strings.Contains(err.Error(), test.expectedErr) {
+					t.Fatalf("expected %q, got %q", test.expectedErr, err.Error())
+				}
+			}
+		})
+	}
+}
+
 func TestWaitForDeletionIgnoreNotFound(t *testing.T) {
 	scheme := runtime.NewScheme()
 	listMapping := map[schema.GroupVersionResource]string{

test/cmd/wait.sh

@@ -26,7 +26,14 @@ run_wait_tests() {
 
     create_and_use_new_namespace
 
-    ### Wait for deletion using --all flag
+    # wait --for=create should time out
+    set +o errexit
+    # Command: Wait with jsonpath support fields not exist in the first place
+    output_message=$(kubectl wait --for=create deploy/test-1 --timeout=1s 2>&1)
+    set -o errexit
+
+    # Post-Condition: Wait failed
+    kube::test::if_has_string "${output_message}" 'timed out waiting for the condition'
 
     # create test data
     kubectl create deployment test-1 --image=busybox
@@ -120,3 +127,4 @@ EOF
     set +o nounset
     set +o errexit
 }
+