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Admin cutover improve the pod label watch function #881

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Merged
spai-p9 merged 5 commits into from
Sep 10, 2025
Merged

Admin cutover improve the pod label watch function #881

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a345595
Add some debug logs
spai-p9 Sep 8, 2025
957c074
Add timeout for the client
spai-p9 Sep 8, 2025
980a003
increase timeout for watch and retry incase of error
spai-p9 Sep 8, 2025
9dbf3f8
remove logs inside the loop
spai-p9 Sep 10, 2025
e50709c
Merge branch 'main' into private/main/ghi-877
spai-p9 Sep 10, 2025
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59 changes: 42 additions & 17 deletions v2v-helper/reporter/reporter.go
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Original file line number Diff line number Diff line change
Expand Up @@ -8,6 +8,7 @@ import (
"math/rand"
"os"
"strings"
"time"

"github.com/platform9/vjailbreak/v2v-helper/pkg/utils"
corev1 "k8s.io/api/core/v1"
Expand Down Expand Up @@ -233,24 +234,48 @@ func (r *Reporter) GetCutoverLabel() (string, error) {

func (r *Reporter) WatchPodLabels(ctx context.Context, ch chan<- string) {
go func() {
watch, err := r.Clientset.CoreV1().Pods(r.PodNamespace).Watch(ctx, metav1.ListOptions{
FieldSelector: fmt.Sprintf("metadata.name=%s", r.PodName),
})
if err != nil {
fmt.Printf("Failed to watch pod labels: %v\n", err)
}
defer watch.Stop()
originalStartCutover := "no"
for event := range watch.ResultChan() {
pod, ok := event.Object.(*corev1.Pod)
if !ok {
continue
}
if cutover, ok := pod.Labels["startCutover"]; ok {
if cutover != originalStartCutover {
ch <- cutover
originalStartCutover = cutover
for {
select {
case <-ctx.Done():
fmt.Printf("Error: Context canceled for pod %s: %v\n", r.PodName, ctx.Err())
return
default:
fmt.Printf("Info: Starting watch for pod %s in namespace %s\n", r.PodName, r.PodNamespace)
timeoutSeconds := int64(172800)
watch, err := r.Clientset.CoreV1().Pods(r.PodNamespace).Watch(ctx, metav1.ListOptions{
FieldSelector: fmt.Sprintf("metadata.name=%s", r.PodName),
TimeoutSeconds: &timeoutSeconds,
})
if err != nil {
fmt.Printf("Error: Failed to start watch for pod %s: %v\n", r.PodName, err)
time.Sleep(5 * time.Second)
continue
}
Comment on lines +245 to +253
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@OmkarDeshpande7 OmkarDeshpande7 Sep 9, 2025

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@spai-p9 Won't this create infinite watchers?

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@OmkarDeshpande7 OmkarDeshpande7 Sep 9, 2025

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It will hog resources on the pod

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@spai-p9 spai-p9 Sep 10, 2025

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This only creates one watcher and the inner loop is a blocking for loop which does not exits until the channel gets closed, hence only one watch is present at a given particular time. the outer for loop is to ensure that if a channel gets closed due to some reason we create a new watch so we don't miss any update.

fmt.Printf("Info: Watch established for pod %s with timeout %d seconds\n", r.PodName, timeoutSeconds)
defer watch.Stop()
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OmkarDeshpande7 marked this conversation as resolved.
originalStartCutover := "no"
fmt.Printf("Info: Entering event loop for pod %s\n", r.PodName)
for event := range watch.ResultChan() {
pod, ok := event.Object.(*corev1.Pod)
if !ok {
fmt.Printf("Error: Received non-pod event for pod %s: %v\n", r.PodName, event.Object)
continue
}
if cutover, ok := pod.Labels["startCutover"]; ok {
if cutover != originalStartCutover {
fmt.Printf("Info: Label changed for pod %s: %s -> %s\n", r.PodName, originalStartCutover, cutover)
select {
case ch <- cutover:
fmt.Printf("Info: Sent label %s for pod %s to channel\n", cutover, r.PodName)
default:
fmt.Printf("Error: Channel blocked when sending label %s for pod %s\n", cutover, r.PodName)
}
originalStartCutover = cutover
}
}
}
fmt.Printf("Info: Watch channel closed for pod %s after ~%d seconds, retrying...\n", r.PodName, timeoutSeconds)
time.Sleep(5 * time.Second)
}
}
}()
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