Virtual Kubelet keeps connections established to remote kubernetes api

[serhii-kolomiiets]

What happened:

There is an issue with established connections to the remote Kubernetes API on Virtual Kubelet. After stopping port-forwarding to a pod running on the virtual node, the connection to the remote Kubernetes API remains active.

What you expected to happen:

The connection to the remote Kubernetes API should be terminated after port-forwarding is completed.

How to reproduce it (as minimally and precisely as possible):

1. This pod is deployed on virtual node:
   apiVersion: v1
   kind: Pod
   metadata:
   name: vk-pf-test
   namespace: default
   spec:
   containers:

• name: main
  image: nginx:1.14.2
  ports:
  • containerPort: 80

2. port-forward execution:
   kubectl port-forward vk-pf-test 8080:80 -n default

3.1. Inside virtual kubelet pod:
watch "netstat -an |grep 'remote_kube_api_ip' |grep ESTABLISHED |wc -l"

3.2. Execute several times from local shell:
curl http://127.0.0.1:8080/

After that we can see that amount of connections from 3.1 command grows, and, even when port-forwarding is dropped, amount of connections is still the same.
This behaviour overloads NAT which is in the middle of virtual-kubelet and remote Kubernetes api server and, also, with lots of ESTABLISHED connections to remote Kubernetes api virtual-kubelet pod memory consumption also grows, and causes OOM issues.

Environment:

• Liqo version: v0.10.3
• Liqoctl version: Client version: c707856
• Kubernetes version (use kubectl version): v1.29.5-gke.1060000
• Cloud provider or hardware configuration: GCP