本文主要介绍如何使用client-go对k8s集群中的Pod进行相关操作，也是自己在工作和学习中使用client-go的相关经验总结
一、初始化Pod连接客户端
本质上是对创建与k8s交互客户端的二次封装，可以基于返回的结构体对象扩展不同的方法，每个方法对应着pod不同的操作，既提高了代码的可读性又避免了在对pod进行不同操作时需要反复初始化客户端的问题
type PodBox struct {
Clientset kubernetes.Interface
Config *restclient.Config
}
func NewPodBox() (*PodBox, error) {
kubeconfig := "k8s集群config配置文件"
//kubecofig转换为clientConfig
clientConfig,err := clientcmd.NewClientConfigFromBytes([]byte(kubeconfig))
if err != nil {
return nil,tracerr.Wrap(err)
}
//clientConfig转换为rest.config
config,err := clientConfig.ClientConfig()
if err != nil {
return nil,tracerr.Wrap(err)
}
//创建k8s客户端
cs,err := kubernetes.NewForConfig(config)
if err != nil {
return nil,tracerr.Wrap(err)
}
podBox := &PodBox{
Clientset: cs,
Config: config,
}
return podBox,nil
}
二、获取Pod实例
func (box *PodBox) Get(podName, namespace string) (*coreV1.Pod,error) {
return box.Clientset.CoreV1().Pods(namespace).Get(context.TODO(),podName,metav1.GetOptions{})
}
2.1 获取Pod状态
const (
ContainersReady string = "ContainersReady"
PodInitialized string = "Initialized"
PodReady string = "Ready"
PodScheduled string = "PodScheduled"
)
const (
ConditionTrue string = "True"
ConditionFalse string = "False"
ConditionUnknown string = "Unknown"
)
// GetPodStatus
// 获取Pod状态
// Pending
// Running
// Successed
// Unavailable
// Initializing
// Scheduling
// NotReady
// Failed
func GetPodStatus(pod *coreV1.Pod) string {
for _,cond := range pod.Status.Conditions {
if string(cond.Type) == ContainersReady {
if string(cond.Status) != ConditionTrue {
return "Unavailable"
}
} else if string(cond.Type) == PodInitialized && string(cond.Status) != ConditionTrue {
return "Initializing"
} else if string(cond.Type) == PodReady {
if string(cond.Status) != ConditionTrue {
return "Unavailable"
}
for _,containerState := range pod.Status.ContainerStatuses {
if !containerState.Ready {
return "Unavailable"
}
}
} else if string(cond.Type) == PodScheduled && string(cond.Status) != ConditionTrue {
return "Scheduling"
}
}
return string(pod.Status.Phase)
}
2.2 获取Pod内容器最大重启次数
func MaxContainerRestarts(pod *coreV1.Pod) int {
maxRestarts := 0
for _, c := range pod.Status.ContainerStatuses {
maxRestarts = integer.IntMax(maxRestarts, int(c.RestartCount))
}
return maxRestarts
}
2.3 获取pod内容器日志
// WatchContainerLogWithPodNameAndContainerName
// 根据命名空间和pod名称以及容器名称，从k8s-apiserver读取容器日志流
//入参：
//Container:容器名称
//Follow:跟踪Pod的日志流，默认为false（关闭）对应kubectl logs命令中的 -f 参数
//TailLines:如果设置，则显示从日志末尾开始的行数。如果未指定，则从容器的创建开始或从秒开始或从时间开始显示日志
//Previous:返回以前终止的容器日志。默认为false（关闭）
func WatchContainerLogWithPodNameAndContainerName(clientset *kubernetes.Clientset, namespace, podName,
containerName string,tailLine int64, previous bool) (io.ReadCloser, error) {
logOpt := &coreV1.PodLogOptions{
Container: containerName,
Follow: true,
TailLines: &tailLine,
Previous: previous,
}
req := clientset.CoreV1().Pods(namespace).GetLogs(podName,logOpt)
return req.Stream(context.TODO())
}
三、根据deployment名称获取pod列表
// PodsGetWithDeploymentNameAndNS
// 根据命名空间和deployment名称，从k8s处获取deployment拥有的pod列表
func PodsGetWithDeploymentNameAndNS(clientset *kubernetes.Clientset, namespace,
deploymentName string) ([]coreV1.Pod, error) {
label := "app="+deploymentName
podList,err := clientset.CoreV1().Pods(namespace).List(context.TODO(),metav1.ListOptions{LabelSelector: label})
if err != nil {
return nil,tracerr.Wrap(err)
}
return podList.Items,nil
}
四、删除Pod
func (box *PodBox) Delete(podName, namespace string) error {
return box.Clientset.CoreV1().Pods(namespace).Delete(context.TODO(),podName,metav1.DeleteOptions{})
}
五、在Pod的容器中执行命令
func (box *PodBox) Exec(cmd []string, ptyHandler PtyHandler, namespace, podName, containerName string) error {
defer func() {
ptyHandler.Done()
}()
req := box.Clientset.CoreV1().RESTClient().Post().
Resource("pods").Name(podName).
Namespace(namespace).SubResource("exec").
VersionedParams(&coreV1.PodExecOptions{
Container: containerName,
Command: cmd,
Stdin: !(ptyHandler.Stdin() == nil),
Stdout: !(ptyHandler.Stdout() == nil),
Stderr: !(ptyHandler.Stderr() == nil),
TTY: ptyHandler.Tty(),
},scheme.ParameterCodec)
exec,err := remotecommand.NewSPDYExecutor(box.Config,"POST",req.URL())
if err != nil {
return tracerr.Wrap(err)
}
err = exec.Stream(remotecommand.StreamOptions{
Stdin: ptyHandler.Stdin(),
Stdout: ptyHandler.Stdout(),
Stderr: ptyHandler.Stderr(),
TerminalSizeQueue: ptyHandler,
Tty: ptyHandler.Tty(),
})
if err != nil {
return tracerr.Wrap(err)
}
return nil
}
六、Pod内文件下载
func (box *PodBox) CopyFromPod(namespace, podName, containerName, filePath string) (io.Reader,error) {
filedir,filename := filepath.Split(filePath)
cmd := []string {"sh", "-c", fmt.Sprintf("cd %s && if [ ! -f ./%s ]; then exit 100; fi && tar cf - %s", filedir,filename,filename)}
reader,outstream := io.Pipe()
ts := NewTerminalSession(nil,outstream,outstream)
go func() {
defer outstream.Close()
err := box.Exec(cmd,ts,namespace,podName,containerName)
if err != nil {
tracerr.Print(err)
}
}()
return reader,nil
}
type sizeQueue struct {
resizeChan chan remotecommand.TerminalSize
doneChan chan struct{}
}
type TerminalSession struct {
stdin io.Reader
stdout io.Writer
stderr io.Writer
sizeQueue
tty bool
}
func NewTerminalSession(stdin io.Reader,stdout io.Writer,stderr io.Writer) *TerminalSession {
return &TerminalSession{
stdin: stdin,
stdout: stdout,
stderr: stderr,
tty: false,
sizeQueue: sizeQueue{
resizeChan: make(chan remotecommand.TerminalSize),
doneChan: make(chan struct{}),
},
}
}
