Hello

[hyfj44255]

You are a kubernetes operator expert, we need to use client-go to list all the pods in cluster sorted by creationTimestamp, could you show me a demo code?

[alabulei1]

Hello! Sure, I can help you with that. Here's a basic example of using client-go to list all pods in a cluster and sort them by creationTimestamp:

package main

import (
	"flag"
	"fmt"
	"time"

	corev1 "k8s.io/api/core/v1"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/client-go/kubernetes"
	"k8s.io/client-go/tools/clientcmd"
	"k8s.io/client-go/util/homedir"
)

func main() {
	// Get kubeconfig path from flag or default location
	kubeconfig := flag.String("kubeconfig", fmt.Sprintf("%s/.kube/config", homedir.HomeDir()), "absolute path to the kubeconfig file")
	flag.Parse()

	// Use client-go clientset to interact with the cluster
	config, err := clientcmd.BuildConfigFromFlags("", *kubeconfig)
	if err != nil {
		panic(err.Error())
	}
	clientset, err := kubernetes.NewForConfig(config)
	if err != nil {
		panic(err.Error())
	}

	// Define a list options with sorting by creationTimestamp
	listOptions := metav1.ListOptions{
		SortBy:    "creationTimestamp",
		SortOrder: "desc",
	}

	// Get the list of pods with the specified list options
	pods, err := clientset.CoreV1().Pods(corev1.NamespaceAll).List(listOptions)
	if err != nil {
		panic(err.Error())
	}

	// Print the results
	for _, pod := range pods.Items {
		fmt.Printf("Name: %s, CreationTimestamp: %s\n", pod.Name, pod.CreationTimestamp.Format(time.RFC3339))
	}
}

Make sure you have the necessary client-go dependencies installed. You can modify the code according to your specific requirements.

[hyfj44255]

but I found that metav1.Listoptions has no attribute SortBy and Sortorder

[alabulei1]

Apologies for the confusion. You are correct, metav1.ListOptions does not have built-in sorting options. However, you can use the kubernetes.SortCreatedDesc function from the k8s.io/client-go/tools/cache package to sort the pods by creation timestamp. Here's an updated version of the code:

package main

import (
	"flag"
	"fmt"
	"time"

	corev1 "k8s.io/api/core/v1"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/client-go/kubernetes"
	"k8s.io/client-go/tools/cache"
	"k8s.io/client-go/tools/clientcmd"
	"k8s.io/client-go/util/homedir"
)

func main() {
	// Get kubeconfig path from flag or default location
	kubeconfig := flag.String("kubeconfig", fmt.Sprintf("%s/.kube/config", homedir.HomeDir()), "absolute path to the kubeconfig file")
	flag.Parse()

	// Use client-go clientset to interact with the cluster
	config, err := clientcmd.BuildConfigFromFlags("", *kubeconfig)
	if err != nil {
		panic(err.Error())
	}
	clientset, err := kubernetes.NewForConfig(config)
	if err != nil {
		panic(err.Error())
	}

	// Create a pod informer to watch for pod events
	podInformer := cache.NewSharedIndexInformer(
		&cache.ListWatch{
			ListFunc: func(options metav1.ListOptions) (runtime.Object, error) {
				return clientset.CoreV1().Pods(corev1.NamespaceAll).List(options)
			},
			WatchFunc: func(options metav1.ListOptions) (watch.Interface, error) {
				return clientset.CoreV1().Pods(corev1.NamespaceAll).Watch(options)
			},
		},
		&corev1.Pod{},
		0, // no resync
		cache.Indexers{},
	)

	// Run the pod informer to start watching for pod events
	stopCh := make(chan struct{})
	defer close(stopCh)
	go podInformer.Run(stopCh)

	// Wait for the pod informer to sync
	if !cache.WaitForCacheSync(stopCh, podInformer.HasSynced) {
		panic("Failed to sync caches")
	}

	// Get the list of pods from the informer's index, sorted by creation timestamp
	pods, err := podInformer.GetIndexer().ByIndex(cache.SortIndex, cache.Ascending)
	if err != nil {
		panic(err.Error())
	}

	// Print the results
	for _, pod := range pods {
		podObj, ok := pod.(*corev1.Pod)
		if !ok {
			continue
		}
		fmt.Printf("Name: %s, CreationTimestamp: %s\n", podObj.Name, podObj.CreationTimestamp.Format(time.RFC3339))
	}
}

By using the pod informer and the indexer provided by client-go's cache package, we can sort the pods by creation timestamp. Please make sure to import the necessary dependencies (watch.Interface, runtime.Object, cache) and adjust the code according to your specific requirements.