TCP connections not reused when HTTP proxy-url is set

[cedws]

In our corporate environment, we're only able to access our clusters via a HTTP proxy. We set the proxy-url field in our configs to do this. It looks something like this:

apiVersion: v1
kind: Config
clusters:
  - name: rancher-desktop
    cluster:
      server: https://127.0.0.1:6443
      proxy-url: http://localhost:5555
      certificate-authority-data: ...
      insecure-skip-tls-verify: false
...

I've noticed that interacting with the cluster through k9s is much slower when this proxy is in use compared to hitting the API server directly

I did a test on my personal machine with just Rancher Desktop and a basic HTTP CONNECT proxy from a gist.

If proxy-url is unset, the connections are reused as expected and new connections are not spawned from actions in k9s.

When proxy-url is in use, I can see that significantly more TCP connections from the client are opened in Wireshark, as if they aren't being reused at all. Most actions in k9s like describing a pod open a new connection. The connections are also left open for a long time.

I'm assuming this is a bug in client-go but could also be in k9s, not too sure yet. I would like to try and write a quick test program that retrieves pods or something since kubectl doesn't run for long enough to demonstrate if TCP connection pooling is working properly.

[cedws]

Wrote a quick test program and can't produce the same effect, so looks like a bug in k9s. Closing.

package main

import (
    "context"
    "flag"
    "fmt"
    "log"
    "time"

    v1 "k8s.io/apimachinery/pkg/apis/meta/v1"
    "k8s.io/client-go/kubernetes"
    "k8s.io/client-go/tools/clientcmd"
)

func main() {
    kubeconfig := flag.String("kubeconfig", "", "path to the kubeconfig file")
    flag.Parse()

    // Use the current context in kubeconfig
    config, err := clientcmd.BuildConfigFromFlags("", *kubeconfig)
    if err != nil {
        log.Fatal(err)
    }

    // Create a new Kubernetes client
    clientset, err := kubernetes.NewForConfig(config)
    if err != nil {
        log.Fatal(err)
    }

    for range time.Tick(1 * time.Second) {
        // Retrieve the list of pods in the default namespace
        pods, err := clientset.CoreV1().Pods("kube-system").List(context.Background(), v1.ListOptions{})
        if err != nil {
            log.Fatal(err)
        }

        // Print the name of each pod
        for _, pod := range pods.Items {
            fmt.Println(pod.Name)
        }
    }
}