From bc5302ec93b280d2816522b8a4b9b41e0b24f965 Mon Sep 17 00:00:00 2001
From: kita456 <g140702@gmail.com>
Date: Sun, 8 Mar 2026 12:05:32 +0900
Subject: [PATCH] fix: kubectl drain --disable-eviction --dry-run=server
 hanging indefinitely

---
 staging/src/k8s.io/kubectl/pkg/drain/drain.go |  5 ++
 .../k8s.io/kubectl/pkg/drain/drain_test.go    | 65 +++++++++++++++++++
 2 files changed, 70 insertions(+)

diff --git a/staging/src/k8s.io/kubectl/pkg/drain/drain.go b/staging/src/k8s.io/kubectl/pkg/drain/drain.go
index b280d20ba96..061972493bf 100644
--- a/staging/src/k8s.io/kubectl/pkg/drain/drain.go
+++ b/staging/src/k8s.io/kubectl/pkg/drain/drain.go
@@ -394,6 +394,11 @@ func (d *Helper) deletePods(pods []corev1.Pod, getPodFn func(namespace, name str
 			d.OnPodDeletionOrEvictionStarted(&pod, false)
 		}
 	}
+
+	if d.DryRunStrategy == cmdutil.DryRunServer {
+		return nil
+	}
+
 	ctx := d.getContext()
 	params := waitForDeleteParams{
 		ctx:                             ctx,
diff --git a/staging/src/k8s.io/kubectl/pkg/drain/drain_test.go b/staging/src/k8s.io/kubectl/pkg/drain/drain_test.go
index 373241054b6..edb250ceb3e 100644
--- a/staging/src/k8s.io/kubectl/pkg/drain/drain_test.go
+++ b/staging/src/k8s.io/kubectl/pkg/drain/drain_test.go
@@ -17,6 +17,7 @@ limitations under the License.
 package drain
 
 import (
+	"bytes"
 	"context"
 	"errors"
 	"fmt"
@@ -38,6 +39,7 @@ import (
 	"k8s.io/apimachinery/pkg/types"
 	"k8s.io/client-go/kubernetes/fake"
 	ktest "k8s.io/client-go/testing"
+	cmdutil "k8s.io/kubectl/pkg/cmd/util"
 )
 
 func TestDeletePods(t *testing.T) {
@@ -461,6 +463,69 @@ func TestDeleteOrEvict(t *testing.T) {
 	}
 }
 
+func TestDeleteOrEvictWithDryRunServer(t *testing.T) {
+	testCases := []struct {
+		description     string
+		disableEviction bool
+	}{
+		{
+			description:     "Eviction enabled with server dry-run",
+			disableEviction: false,
+		},
+		{
+			description:     "Eviction disabled with server dry-run",
+			disableEviction: true,
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.description, func(t *testing.T) {
+			var buf bytes.Buffer
+			h := &Helper{
+				Out:                &buf,
+				GracePeriodSeconds: 10,
+				DisableEviction:    tc.disableEviction,
+				DryRunStrategy:     cmdutil.DryRunServer,
+			}
+
+			var allPods []runtime.Object
+			var podsToDelete []corev1.Pod
+
+			for i := 1; i <= 4; i++ {
+				pod := corev1.Pod{
+					ObjectMeta: metav1.ObjectMeta{
+						Name:      fmt.Sprintf("mypod-%d", i),
+						Namespace: "default",
+					},
+				}
+				allPods = append(allPods, &pod)
+				if i <= 2 {
+					podsToDelete = append(podsToDelete, pod)
+				}
+			}
+
+			k := fake.NewSimpleClientset(allPods...)
+
+			// fake clientset will actually delete objects from the in-memory store.
+			// This reactor intercepts delete requests with DryRun set and returns success without
+			// removing the object, simulating real API server dry-run behavior.
+			k.PrependReactor("delete", "pods", func(actions ktest.Action) (bool, runtime.Object, error) {
+				deleteAction := actions.(ktest.DeleteAction)
+				if len(deleteAction.GetDeleteOptions().DryRun) > 0 {
+					return true, nil, nil
+				}
+				return false, nil, nil
+			})
+			addEvictionSupport(t, k, "v1")
+			h.Client = k
+
+			if err := h.DeleteOrEvictPods(podsToDelete); err != nil {
+				t.Fatalf("error from DeleteOrEvictPods: %v", err)
+			}
+		})
+	}
+}
+
 func mockFilterSkip(_ corev1.Pod) PodDeleteStatus {
 	return MakePodDeleteStatusSkip()
 }