2. kubectl输出格式化
之前在给一线的驻场同学做工具时，需要格式化输出一些 Pod 关键信息，比如 Pod 状态、最近启动时间等等：
当时想参考 kubectl 的代码实现，结果没找到，仔细检查后才发现格式化输出与 Pod 状态转换逻辑都是在 kube-apiserver 里。
以获取 pod 列表为例，kubectl get pod 命令输出的 STATUS 字段，实际上是在服务端计算完成的，当请求头中若存在 as=Table;v=v1;g=meta.k8s.io,application/json;as=Table;v=v1beta1;g=meta.k8s.io,application/json，kube-apiserver 响应数据时就会以表格的形式返回：
我们可以在 Kubernetes 的 pkg/printers 中找到展示数据的逻辑：
printtPod 函数中就有我们需要的状态转换逻辑：
搭配 controller-runtime 的 client 包，我们就可以做一些与 kubectl 输出结果一致的命令行工具。
下面是获取集群中所有租户的 deployment 关联的 Pod 信息的例子：
package main
import (
"context"
"fmt"
"log"
"os"
"path/filepath"
"sort"
"strings"
"time"
"github.com/jedib0t/go-pretty/v6/table"
"github.com/pkg/errors"
appsv1 "k8s.io/api/apps/v1"
corev1 "k8s.io/api/core/v1"
"k8s.io/client-go/tools/clientcmd"
"sigs.k8s.io/controller-runtime/pkg/client"
)
func main() {
// 初始化context，设定一个60秒超时的总时长
ctx, cancel := context.WithTimeout(context.Background(), time.Second*60)
defer cancel()
// 获取一个访问kube-apiserver的client
c, err := getClient(ctx)
if err != nil {
log.Printf("get client error: %s\n", err)
return
}
// 获取所有的deployment
deployList := &appsv1.DeploymentList{}
if err := c.List(ctx, deployList); err != nil {
log.Printf("list deployment error: %s\n", err)
return
}
// 遍历deployment，筛选出租户命名空间下的deployment
items := []*appsv1.Deployment{}
for i := range deployList.Items {
item := &deployList.Items[i]
if strings.HasPrefix(item.Namespace, "tenant") && strings.Contains(item.Name, "cks") {
items = append(items, item)
}
}
// 按命名空间和名称排序
sort.Slice(items, func(i, j int) bool {
if items[i].Namespace != items[j].Namespace {
return items[i].Namespace < items[j].Namespace
}
return items[i].Name < items[j].Name
})
log.Printf("***打印Pod启动10分钟后出现过重启的容器信息***\n")
fmt.Println()
// 遍历deployment列表
for _, deploy := range items {
log.Printf("deployment: %s/%s \n", deploy.Namespace, deploy.Name)
// 使用dployment的selector过滤出pod
podList := &corev1.PodList{}
if err := c.List(ctx, podList, client.InNamespace(deploy.Namespace), client.MatchingLabels(deploy.Spec.Selector.MatchLabels)); err != nil {
log.Printf("list pod error: %s\n", err)
return
}
// 根据pod名称排序
sort.Slice(podList.Items, func(i, j int) bool {
return podList.Items[i].Name < podList.Items[j].Name
})
// 遍历pod列表，检查Pod是否需要打印（pod启动10分钟后未ready或发生过重启）
for _, pod := range podList.Items {
if ok := checkPod(&pod); ok {
log.Printf("pod: %s/%s status: normal\n", pod.Namespace, pod.Name)
continue
}
log.Printf("pod: %s/%s status: error\n", pod.Namespace, pod.Name)
printPod(&pod)
}
fmt.Println()
}
}
func getClient(ctx context.Context) (client.Client, error) {
home, err := os.UserHomeDir()
if err != nil {
return nil, errors.Wrap(err, "get home dir")
}
kubeconfigPath := filepath.Join(home, ".kube", "config")
data, err := os.ReadFile(kubeconfigPath)
if err != nil {
return nil, errors.Wrap(err, "read kubeconfig")
}
config, err := clientcmd.RESTConfigFromKubeConfig(data)
if err != nil {
return nil, errors.Wrap(err, "parse kubeconfig")
}
c, err := client.New(config, client.Options{})
if err != nil {
return nil, errors.Wrap(err, "initialize kubeClient")
}
return c, nil
}
func checkPod(pod *corev1.Pod) bool {
var ready bool
for _, v := range pod.Status.Conditions {
if v.Type == corev1.PodReady && v.Status == corev1.ConditionTrue {
ready = true
break
}
}
if !ready {
return false
}
timeoutTimestamp := pod.CreationTimestamp.Add(time.Minute * 10)
for _, v := range pod.Status.ContainerStatuses {
if v.State.Waiting != nil || v.State.Terminated != nil {
return false
}
if v.State.Running != nil && v.State.Running.StartedAt.After(timeoutTimestamp) {
return false
}
}
return true
}
func printPod(pod *corev1.Pod) {
sort.Slice(pod.Status.ContainerStatuses, func(i, j int) bool {
return pod.Status.ContainerStatuses[i].Name < pod.Status.ContainerStatuses[j].Name
})
total := 0
t := table.NewWriter()
t.AppendHeader(table.Row{"名称", "ready", "最近启动时间", "上次退出时间", "上次退出原因", "上次退出码", "重启次数"})
recentCntrName := "null"
recentCntrTime := time.Time{}
timeoutTimestamp := pod.CreationTimestamp.Add(time.Minute * 10)
for _, v := range pod.Status.ContainerStatuses {
if v.RestartCount == 0 {
continue
}
total += int(v.RestartCount)
var startedAt = "null"
if v.State.Running != nil {
if !v.State.Running.StartedAt.After(timeoutTimestamp) {
continue
}
startedAt = v.State.Running.StartedAt.Format("2006-01-02 15:04:05")
}
var lastStateFinishedAt = "null"
var lastStateReason = "null"
var lastStateExitCode = "null"
if v.LastTerminationState.Terminated != nil {
lastStateFinishedAt = v.LastTerminationState.Terminated.FinishedAt.Format("2006-01-02 15:04:05")
lastStateReason = v.LastTerminationState.Terminated.Reason
lastStateExitCode = fmt.Sprintf("%d", v.LastTerminationState.Terminated.ExitCode)
if v.LastTerminationState.Terminated.FinishedAt.After(recentCntrTime) {
recentCntrName = v.Name
recentCntrTime = v.LastTerminationState.Terminated.FinishedAt.Time
}
}
t.AppendRow(table.Row{
v.Name,
v.Ready,
startedAt,
lastStateFinishedAt,
lastStateReason,
lastStateExitCode,
v.RestartCount,
})
t.AppendSeparator()
}
t.SetTitle("创建时间: %s => 重启次数: %d => 最近重启容器: %s @ %s", pod.CreationTimestamp.Format("2006-01-02 15:04:05"), total, recentCntrName, recentCntrTime.Format("2006-01-02 15:04:05"))
fmt.Println(t.Render())
}