package main
import (
"flag"
"fmt"
crdv1beta1 "github.com/cnych/controller-demo/pkg/apis/stable/v1beta1"
"k8s.io/apimachinery/pkg/api/errors"
"k8s.io/apimachinery/pkg/util/runtime"
"k8s.io/apimachinery/pkg/util/wait"
"k8s.io/client-go/tools/cache"
"k8s.io/client-go/util/workqueue"
"os"
"os/signal"
"path/filepath"
"syscall"
"time"
"github.com/golang/glog"
"k8s.io/client-go/tools/clientcmd"
"k8s.io/client-go/util/homedir"
"k8s.io/klog"
clientset "github.com/cnych/controller-demo/pkg/client/clientset/versioned"
"github.com/cnych/controller-demo/pkg/client/informers/externalversions"
informers "github.com/cnych/controller-demo/pkg/client/informers/externalversions/stable/v1beta1"
)
type Controller struct {
informer informers.CronTabInformer
workqueue workqueue.RateLimitingInterface
}
var (
onlyOneSignalHandler = make(chan struct{})
shutdownSignals = []os.Signal{os.Interrupt, syscall.SIGTERM}
kubeconfig *string
)
// SetupSignalHandler 注册 SIGTERM 和 SIGINT 信号
// 返回一个 stop channel，该通道在捕获到第一个信号时被关闭
// 如果捕捉到第二个信号，程序将直接退出
func setupSignalHandler() (stopCh <-chan struct{}) {
// 当调用两次的时候 panics
close(onlyOneSignalHandler)
stop := make(chan struct{})
c := make(chan os.Signal, 2)
// Notify 函数让 signal 包将输入信号转发到 c
// 如果没有列出要传递的信号，会将所有输入信号传递到 c；否则只传递列出的输入信号
signal.Notify(c, shutdownSignals...)
go func() {
<-c
close(stop)
<-c
os.Exit(1) // 第二个信号，直接退出
}()
return stop
}
func main() {
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()
// 处理信号量
stopCh := setupSignalHandler()
// 处理入参
cfg, err := clientcmd.BuildConfigFromFlags("", *kubeconfig)
if err != nil {
glog.Fatalf("Error building kubeconfig: %s", err.Error())
}
crontabClient, err := clientset.NewForConfig(cfg)
if err != nil {
glog.Fatalf("Error building example clientset: %s", err.Error())
}
// informerFactory 工厂类， 这里注入我们通过代码生成的 client
// clent 主要用于和 API Server 进行通信，实现 ListAndWatch
crontabInformerFactory := externalversions.NewSharedInformerFactory(crontabClient, time.Second*30)
// 实例化自定义控制器
controller := NewController(crontabInformerFactory.Stable().V1beta1().CronTabs())
// 启动 informer，开始List & Watch
go crontabInformerFactory.Start(stopCh)
if err = controller.Run(2, stopCh); err != nil {
klog.Fatalf("Error running controller: %s", err.Error())
}
}
func NewController(informer informers.CronTabInformer) *Controller {
//使用client 和前面创建的 Informer，初始化了自定义控制器
controller := &Controller{
informer: informer,
// WorkQueue 的实现，负责同步 Informer 和控制循环之间的数据
workqueue: workqueue.NewNamedRateLimitingQueue(workqueue.DefaultControllerRateLimiter(), "CronTab"),
}
klog.Info("Setting up crontab event handlers")
// informer 注册了三个 Handler（AddFunc、UpdateFunc 和 DeleteFunc）
// 分别对应 API 对象的“添加”“更新”和“删除”事件。
// 而具体的处理操作，都是将该事件对应的 API 对象加入到工作队列中
informer.Informer().AddEventHandler(cache.ResourceEventHandlerFuncs{
AddFunc: controller.enqueueCronTab,
UpdateFunc: func(old, new interface{}) {
oldObj := old.(*crdv1beta1.CronTab)
newObj := new.(*crdv1beta1.CronTab)
// 如果资源版本相同则不处理
if oldObj.ResourceVersion == newObj.ResourceVersion {
return
}
controller.enqueueCronTab(new)
},
DeleteFunc: controller.enqueueCronTabForDelete,
})
return controller
}
func (c *Controller) Run(threadiness int, stopCh <-chan struct{}) error {
defer runtime.HandleCrash()
defer c.workqueue.ShutDown()
// 记录开始日志
klog.Info("Starting CronTab control loop")
klog.Info("Waiting for informer caches to sync")
if ok := cache.WaitForCacheSync(stopCh, c.informer.Informer().HasSynced); !ok {
return fmt.Errorf("failed to wait for caches to sync")
}
klog.Info("Starting workers")
for i := 0; i < threadiness; i++ {
go wait.Until(c.runWorker, time.Second, stopCh)
}
klog.Info("Started workers")
<-stopCh
klog.Info("Shutting down workers")
return nil
}
// runWorker 是一个死循环，一直会调用 c.processNextWorkItem 从workqueue读取元素
func (c *Controller) runWorker() {
for c.processNextWorkItem() {
}
}
// 从workqueue消费元素
func (c *Controller) processNextWorkItem() bool {
obj, shutdown := c.workqueue.Get()
if shutdown {
return false
}
err := func(obj interface{}) error {
defer c.workqueue.Done(obj)
var key string
var ok bool
if key, ok = obj.(string); !ok {
c.workqueue.Forget(obj)
runtime.HandleError(fmt.Errorf("expected string in workqueue but got %#v", obj))
return nil
}
if err := c.syncHandler(key); err != nil {
return fmt.Errorf("error syncing '%s': %s", key, err.Error())
}
c.workqueue.Forget(obj)
klog.Infof("Successfully synced '%s'", key)
return nil
}(obj)
if err != nil {
runtime.HandleError(err)
return true
}
return true
}
// 从 Informer 维护的缓存中拿到了它所对应的 CronTab 对象
func (c *Controller) syncHandler(key string) error {
namespace, name, err := cache.SplitMetaNamespaceKey(key)
if err != nil {
runtime.HandleError(fmt.Errorf("invalid resource key: %s", key))
return nil
}
crontab, err := c.informer.Lister().CronTabs(namespace).Get(name)
//从缓存中拿不到这个对象,那就意味着这个 CronTab 对象的 Key 是通过前面的“删除”事件添加进工作队列的。
if err != nil {
if errors.IsNotFound(err) {
// 对应的 crontab 对象已经被删除了
klog.Warningf("[CronTabCRD] %s/%s does not exist in local cache, will delete it from CronTab ...",
namespace, name)
klog.Infof("[CronTabCRD] deleting crontab: %s/%s ...", namespace, name)
return nil
}
runtime.HandleError(fmt.Errorf("failed to get crontab by: %s/%s", namespace, name))
return err
}
klog.Infof("[CronTabCRD] try to process crontab: %#v ...", crontab)
return nil
}
func (c *Controller) enqueueCronTab(obj interface{}) {
var key string
var err error
if key, err = cache.MetaNamespaceKeyFunc(obj); err != nil {
runtime.HandleError(err)
return
}
c.workqueue.AddRateLimited(key)
}
func (c *Controller) enqueueCronTabForDelete(obj interface{}) {
var key string
var err error
key, err = cache.DeletionHandlingMetaNamespaceKeyFunc(obj)
if err != nil {
runtime.HandleError(err)
return
}
c.workqueue.AddRateLimited(key)
}