How to collect k8s pods logs in parallel using golang only for a duration of time

I am new to golang, I have a task to collect the application logs, application is running as deployment in k8s cluster, there are 4 pods in total.
As part of test automation, I need to collect the application logs (only for the duration of my test operation) in parallel while I perform some operations on the application and write the logs to a file, and move to the next operation and do the same.

Finally I iterate through the log files one-by-one and filter for certain keywords corresponding to my operation and validate the logs are correct/not.

I am thinking to get the pod logs using kubectl command directly, instead of using the go-sdk as I am facing missing log entries which I couldn't triage with many attempts.

kubectl logs -f -l app=my-app -n dev > /usr/mylogs.txt

I found a way to run this command using exec.Command

command := exec.Command("/bin/sh", "-c", "kubectl logs -f -l app=my-app -n dev > /usr/mylogs.txt")
	err := command.Start()

Now I need to do this in golang,

func myTest(t *testing.T){
  go collectApplicationLogs("test1")
  
  // do application operation 
   // run test
  
  stopLogsCollection ()   -------> how to achieve this?
}

func collectApplicationLogs(fileName string){
   // command to collect the logs to a file
  // kubectl logs -f -l app=my-app -n dev > /usr/{fileName}
}

You can use Kubernetes go-client to get logs from the pods. At first create the clientset from kubenetes config. You can use InclusterConfig or Out of cluster config. I have used out of cluster config here.

const (
// set namespace and label
namespace = "dev"
label     = "app=my-app"
)
func main() {
// parse the .kubeconfig file
var kubeconfig *string
if home := homedir.HomeDir(); home != "" {
kubeconfig = flag.String("kubeconfig", filepath.Join(home, ".kube", "config"), "(optional) absolute path to the kubeconfig file")
} else {
kubeconfig = flag.String("kubeconfig", "", "absolute path to the kubeconfig file")
}
flag.Parse()
// use the current context in kubeconfig
ctx := context.TODO()
config, err := clientcmd.BuildConfigFromFlags("", *kubeconfig)
if err != nil {
log.Println(err, "Failed to build config from flags")
return
}
err = collectApplicationLogs(ctx, config, "/usr/mylogs.txt")
if err != nil {
log.Println(err, "Failed to collect logs")
}
}

To collect logs, you need to list the gods first. Then get logs from each of those pods and append them to the file concurrently.

func collectApplicationLogs(ctx context.Context, config *rest.Config, filename string) error {
// create the clientset
clientSet, err := kubernetes.NewForConfig(config)
if err != nil {
log.Println("Failed to create clientset from the given config")
return err
}
// get the pods as ListItems
pods, err := clientSet.CoreV1().Pods(namespace).List(ctx, metav1.ListOptions{
LabelSelector: label,
})
if err != nil {
log.Println(err, "Failed to get pods")
return err
}
// If the file doesn't exist, create it or append to the file
file, err := os.OpenFile(filename, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0666)
if err != nil {
return err
}
defer file.Close()
// get the pod lists first
// then get the podLogs from each of the pods
// write to files concurrently
// use channel for blocking reasons
ch := make(chan bool)
podItems := pods.Items
for i := 0; i < len(podItems); i++ {
podLogs, err := clientSet.CoreV1().Pods(namespace).GetLogs(podItems[i].Name, &v1.PodLogOptions{
Follow: true,
}).Stream(ctx)
if err != nil {
return err
}
buffer := bufio.NewReader(podLogs)
go writeLogs(buffer, file, ch)
}
<-ch
return nil
}
func writeLogs(buffer *bufio.Reader, file *os.File, ch chan bool) {
defer func() {
ch <- true
}()
for {
str, readErr := buffer.ReadString('\n')
if readErr == io.EOF {
break
}
_, err := file.Write([]byte(str))
if err != nil {
return
}
}
}