keep same node if pod mounts exclusive access PVC (#2)

CHANGELOG.md

@@ -5,6 +5,9 @@
 ### New features
 
 * Show prompt for selecting a Pod in the current namespace when no Pod name is provided as argument.
+* Properly handle Pods that mount persistent storage.
+  Pods that mount a PersistentVolume with exclusive access modes (`ReadWriteOnce`, `ReadWriteOncePod`) are cloned
+  on the same node as the original. This ensures that the duplicate can also mount the same volume.
 
 ### Chores
 

pkg/cmd/pod_test.go

@@ -17,6 +17,7 @@
 package cmd
 
 import (
+	"fmt"
 	"github.com/stretchr/testify/assert"
 	"github.com/telemaco019/duplik8s/pkg/test"
 	"github.com/telemaco019/duplik8s/pkg/test/mocks"
@@ -33,3 +34,23 @@ func Test_NoPodsAvailable(t *testing.T) {
 	assert.NotEmpty(t, output)
 	assert.Error(t, err)
 }
+
+func Test_Success(t *testing.T) {
+	podClient := mocks.NewPodClient(
+		mocks.ListPodsResult{},
+		nil,
+	)
+	cmd := NewRootCmd(podClient)
+	_, err := test.ExecuteCommand(cmd, "pod", "pod-1")
+	assert.NoError(t, err)
+}
+
+func Test_DuplicateError(t *testing.T) {
+	podClient := mocks.NewPodClient(
+		mocks.ListPodsResult{},
+		fmt.Errorf("error"),
+	)
+	cmd := NewRootCmd(podClient)
+	_, err := test.ExecuteCommand(cmd, "pod", "pod-1")
+	assert.EqualError(t, err, "error")
+}

pkg/pods/client.go

@@ -63,24 +63,6 @@ type PodOverrideOptions struct {
 	StartupProbe *v1.Probe
 }
 
-func (o PodOverrideOptions) Apply(pod *v1.Pod) {
-	// Override command
-	if o.Command != nil {
-		for i := range pod.Spec.Containers {
-			pod.Spec.Containers[i].Command = o.Command
-			pod.Spec.Containers[i].Args = o.Args
-			pod.Spec.Containers[i].ReadinessProbe = o.ReadinessProbe
-			pod.Spec.Containers[i].LivenessProbe = o.LivenessProbe
-			pod.Spec.Containers[i].ReadinessProbe = o.ReadinessProbe
-			pod.Spec.Containers[i].StartupProbe = o.StartupProbe
-		}
-	}
-	// Remove assigned nod
-	pod.Spec.NodeName = ""
-	// Override restart policy
-	pod.Spec.RestartPolicy = v1.RestartPolicyNever
-}
-
 func (c *podClient) ListPods(namespace string) ([]string, error) {
 	pods, err := c.clientset.CoreV1().Pods(namespace).List(c.ctx, metav1.ListOptions{})
 	if err != nil {
@@ -121,7 +103,13 @@ func (c *podClient) DuplicatePod(podName string, namespace string, opts PodOverr
 		},
 		Spec: pod.Spec,
 	}
-	opts.Apply(&newPod)
+
+	// override the pod spec
+	configurator := NewPodConfigurator(c.clientset, opts)
+	err = configurator.OverrideSpec(c.ctx, &newPod)
+	if err != nil {
+		return err
+	}
 
 	// create the new pod
 	_, err = c.clientset.CoreV1().Pods(pod.Namespace).Create(c.ctx, &newPod, metav1.CreateOptions{})

pkg/pods/configurator.go

@@ -0,0 +1,94 @@
+/*
+ * Copyright 2024 Michele Zanotti <[email protected]>
+ *
+ * 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 pods
+
+import (
+	"context"
+	v1 "k8s.io/api/core/v1"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/client-go/kubernetes"
+)
+
+type PodConfigurator struct {
+	clientset *kubernetes.Clientset
+	options   PodOverrideOptions
+}
+
+func NewPodConfigurator(clientset *kubernetes.Clientset, options PodOverrideOptions) PodConfigurator {
+	return PodConfigurator{
+		clientset: clientset,
+		options:   options,
+	}
+}
+
+func (c PodConfigurator) OverrideSpec(ctx context.Context, pod *v1.Pod) error {
+	// Override command
+	if c.options.Command != nil {
+		for i := range pod.Spec.Containers {
+			pod.Spec.Containers[i].Command = c.options.Command
+			pod.Spec.Containers[i].Args = c.options.Args
+			pod.Spec.Containers[i].ReadinessProbe = c.options.ReadinessProbe
+			pod.Spec.Containers[i].LivenessProbe = c.options.LivenessProbe
+			pod.Spec.Containers[i].ReadinessProbe = c.options.ReadinessProbe
+			pod.Spec.Containers[i].StartupProbe = c.options.StartupProbe
+		}
+	}
+
+	hasMountOncePvc, err := c.hasMountOncePvc(ctx, *pod)
+	if err != nil {
+		return err
+	}
+
+	// If the Pod does not have any PVC with mount once policy, then remove the node name
+	// to allow the scheduler to schedule the pod on any node
+	if !hasMountOncePvc {
+		pod.Spec.NodeName = ""
+	}
+
+	// Override restart policy
+	pod.Spec.RestartPolicy = v1.RestartPolicyNever
+
+	return nil
+}
+
+func (c PodConfigurator) hasMountOncePvc(ctx context.Context, pod v1.Pod) (bool, error) {
+	for _, volume := range pod.Spec.Volumes {
+		if volume.PersistentVolumeClaim != nil {
+			pvc, err := c.clientset.
+				CoreV1().
+				PersistentVolumeClaims(pod.Namespace).
+				Get(ctx, volume.PersistentVolumeClaim.ClaimName, metav1.GetOptions{})
+			if err != nil {
+				return false, err
+			}
+			return anyMountOnceAccessMode(pvc.Spec.AccessModes), nil
+		}
+	}
+	return false, nil
+}
+
+func anyMountOnceAccessMode(modes []v1.PersistentVolumeAccessMode) bool {
+	for _, mode := range modes {
+		if mode == v1.ReadWriteOnce {
+			return true
+		}
+		if mode == v1.ReadWriteOncePod {
+			return true
+		}
+	}
+	return false
+}

pkg/test/mocks/pod_client.go

@@ -19,8 +19,8 @@ package mocks
 import "github.com/telemaco019/duplik8s/pkg/pods"
 
 type ListPodsResult struct {
-	pods []string
-	err  error
+	Pods []string
+	Err  error
 }
 
 type PodClient struct {
@@ -39,7 +39,7 @@ func NewPodClient(
 }
 
 func (c *PodClient) ListPods(namespace string) ([]string, error) {
-	return c.ListPodsResult.pods, c.ListPodsResult.err
+	return c.ListPodsResult.Pods, c.ListPodsResult.Err
 }
 
 func (c *PodClient) DuplicatePod(podName string, namespace string, opts pods.PodOverrideOptions) error {