client-go workqueue demo

鏈接地址：https://github.com/kubernetes/client-go

[root@wangjq examples]# tree
.
├── create-update-delete-deployment
│   ├── main.go
│   └── README.md
├── dynamic-create-update-delete-deployment
│   ├── main.go
│   └── README.md
├── fake-client
│   ├── doc.go
│   ├── main_test.go
│   └── README.md
├── in-cluster-client-configuration
│   ├── Dockerfile
│   ├── main.go
│   └── README.md
├── leader-election
│   ├── main.go
│   └── README.md
├── out-of-cluster-client-configuration
│   ├── main.go
│   └── README.md
├── README.md
└── workqueue
    ├── main.go
    └── README.md

 demo1

[root@wangjq workqueue]# cat main.go 
/*
Copyright 2017 The Kubernetes Authors.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package main

import (
        "flag"
        "fmt"
        "time"

        "k8s.io/klog"

        v1 "k8s.io/api/core/v1"
        meta_v1 "k8s.io/apimachinery/pkg/apis/meta/v1"
        "k8s.io/apimachinery/pkg/fields"
        "k8s.io/apimachinery/pkg/util/runtime"
        "k8s.io/apimachinery/pkg/util/wait"
        "k8s.io/client-go/kubernetes"
        "k8s.io/client-go/tools/cache"
        "k8s.io/client-go/tools/clientcmd"
        "k8s.io/client-go/util/workqueue"
)

type Controller struct {
        indexer  cache.Indexer
        queue    workqueue.RateLimitingInterface
        informer cache.Controller
}

func NewController(queue workqueue.RateLimitingInterface, indexer cache.Indexer, informer cache.Controller) *Controller {
        return &Controller{
                informer: informer,
                indexer:  indexer,
                queue:    queue,
        }
}

func (c *Controller) processNextItem() bool {
        // Wait until there is a new item in the working queue
        key, quit := c.queue.Get()
        if quit {
                return false
        }
        // Tell the queue that we are done with processing this key. This unblocks the key for other workers
        // This allows safe parallel processing because two pods with the same key are never processed in
        // parallel.
        defer c.queue.Done(key)

        // Invoke the method containing the business logic
        err := c.syncToStdout(key.(string))
        // Handle the error if something went wrong during the execution of the business logic
        c.handleErr(err, key)
        return true
}

// syncToStdout is the business logic of the controller. In this controller it simply prints
// information about the pod to stdout. In case an error happened, it has to simply return the error.
// The retry logic should not be part of the business logic.
func (c *Controller) syncToStdout(key string) error {
        obj, exists, err := c.indexer.GetByKey(key)
        if err != nil {
                klog.Errorf("Fetching object with key %s from store failed with %v", key, err)
                return err
        }

        if !exists {
                // Below we will warm up our cache with a Pod, so that we will see a delete for one pod
                fmt.Printf("Pod %s does not exist anymore\n", key)
        } else {
                // Note that you also have to check the uid if you have a local controlled resource, which
                // is dependent on the actual instance, to detect that a Pod was recreated with the same name
                fmt.Printf("Sync/Add/Update for Pod %s\n", obj.(*v1.Pod).GetName())
        }
        return nil
}

// handleErr checks if an error happened and makes sure we will retry later.
func (c *Controller) handleErr(err error, key interface{}) {
        if err == nil {
                // Forget about the #AddRateLimited history of the key on every successful synchronization.
                // This ensures that future processing of updates for this key is not delayed because of
                // an outdated error history.
                c.queue.Forget(key)
                return
        }

        // This controller retries 5 times if something goes wrong. After that, it stops trying.
        if c.queue.NumRequeues(key) < 5 {
                klog.Infof("Error syncing pod %v: %v", key, err)

                // Re-enqueue the key rate limited. Based on the rate limiter on the
                // queue and the re-enqueue history, the key will be processed later again.
                c.queue.AddRateLimited(key)
                return
        }

        c.queue.Forget(key)
        // Report to an external entity that, even after several retries, we could not successfully process this key
        runtime.HandleError(err)
        klog.Infof("Dropping pod %q out of the queue: %v", key, err)
}

func (c *Controller) Run(threadiness int, stopCh chan struct{}) {
        defer runtime.HandleCrash()

        // Let the workers stop when we are done
        defer c.queue.ShutDown()
        klog.Info("Starting Pod controller")

        go c.informer.Run(stopCh)

        // Wait for all involved caches to be synced, before processing items from the queue is started
        if !cache.WaitForCacheSync(stopCh, c.informer.HasSynced) {
                runtime.HandleError(fmt.Errorf("Timed out waiting for caches to sync"))
                return
        }

        for i := 0; i < threadiness; i++ {
                go wait.Until(c.runWorker, time.Second, stopCh)
        }

        <-stopCh
        klog.Info("Stopping Pod controller")
}

func (c *Controller) runWorker() {
        for c.processNextItem() {
        }
}

func main() {
        var kubeconfig string
        var master string

        flag.StringVar(&kubeconfig, "kubeconfig", "", "absolute path to the kubeconfig file")
        flag.StringVar(&master, "master", "", "master url")
        flag.Parse()

        // creates the connection
        config, err := clientcmd.BuildConfigFromFlags(master, kubeconfig)
        if err != nil {
                klog.Fatal(err)
        }

        // creates the clientset
        clientset, err := kubernetes.NewForConfig(config)
        if err != nil {
                klog.Fatal(err)
        }

        // create the pod watcher
        podListWatcher := cache.NewListWatchFromClient(clientset.CoreV1().RESTClient(), "pods", v1.NamespaceDefault, fields.Everything())

        // create the workqueue
        queue := workqueue.NewRateLimitingQueue(workqueue.DefaultControllerRateLimiter())

        // Bind the workqueue to a cache with the help of an informer. This way we make sure that
        // whenever the cache is updated, the pod key is added to the workqueue.
        // Note that when we finally process the item from the workqueue, we might see a newer version
        // of the Pod than the version which was responsible for triggering the update.
        indexer, informer := cache.NewIndexerInformer(podListWatcher, &v1.Pod{}, 0, cache.ResourceEventHandlerFuncs{
                AddFunc: func(obj interface{}) {
                        key, err := cache.MetaNamespaceKeyFunc(obj)
                        if err == nil {
                                queue.Add(key)
                        }
                },
                UpdateFunc: func(old interface{}, new interface{}) {
                        key, err := cache.MetaNamespaceKeyFunc(new)
                        if err == nil {
                                queue.Add(key)
                        }
                },
                DeleteFunc: func(obj interface{}) {
                        // IndexerInformer uses a delta queue, therefore for deletes we have to use this
                        // key function.
                        key, err := cache.DeletionHandlingMetaNamespaceKeyFunc(obj)
                        if err == nil {
                                queue.Add(key)
                        }
                },
        }, cache.Indexers{})

        controller := NewController(queue, indexer, informer)

        // We can now warm up the cache for initial synchronization.
        // Let's suppose that we knew about a pod "mypod" on our last run, therefore add it to the cache.
        // If this pod is not there anymore, the controller will be notified about the removal after the
        // cache has synchronized.
        indexer.Add(&v1.Pod{
                ObjectMeta: meta_v1.ObjectMeta{
                        Name:      "mypod",
                        Namespace: v1.NamespaceDefault,
                },
        })

        // Now let's start the controller
        stop := make(chan struct{})
        defer close(stop)
        go controller.Run(1, stop)

        // Wait forever
        select {}
}

demo2：

package main
 
import (
    "flag"
    "k8s.io/client-go/kubernetes"
    "k8s.io/client-go/util/workqueue"
    "k8s.io/sample-controller/pkg/signals"
    "k8s.io/client-go/tools/cache"
    "k8s.io/client-go/tools/clientcmd"
    "github.com/golang/glog"
    "k8s.io/apimachinery/pkg/watch"
    metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
    "k8s.io/apimachinery/pkg/runtime"
    utilruntime "k8s.io/apimachinery/pkg/util/runtime"
    apiv1 "k8s.io/api/core/v1"
    "fmt"
    "k8s.io/apimachinery/pkg/util/wait"
    "time"
)
 
/* 控制器 */
type Controller struct {
    // 此控制器使用的客戶端
    clientset kubernetes.Interface
    // 此控制器使用的工作隊列
    queue workqueue.RateLimitingInterface
    // 此控制器使用的共享Informer，SharedIndexInformer可以維護緩存中對象的索引
    informer cache.SharedIndexInformer
}
 
/* 主函數 */
var (
    // 參數變量
    masterURL  string
    kubeconfig string
)
// 啟動控制器
func (c *Controller) Run(stopCh <-chan struct{}) {
    // 捕獲應用程序崩潰並打印日志
    defer utilruntime.HandleCrash()
    // 關閉隊列，從而導致Worker結束
    defer c.queue.ShutDown()
 
    glog.Info("啟動控制器……")
 
    // 運行Informer
    go c.informer.Run(stopCh)
 
    // 在啟動Worker之前，等待緩存同步完成
    if !cache.WaitForCacheSync(stopCh, c.informer.HasSynced) {
        utilruntime.HandleError(fmt.Errorf("同步緩存超時"))
        return
    }
 
    glog.Info("緩存已經同步，准備啟動Worker")
    // 循環執行Worker，直到TERM
    wait.Until(c.runWorker, time.Second, stopCh)
}
 
// 啟動Worker
func (c *Controller) runWorker() {
    for c.processNextItem() {
    }
}
 
// Worker的邏輯框架
func (c *Controller) processNextItem() bool {
    // 最大重試次數
    maxRetries := 3
 
    // 獲取下一個元素，第2個出參提示隊列是否已經關閉
    key, quit := c.queue.Get()
    if quit {
        return false
    }
 
    // 總是移除Key
    defer c.queue.Done(key)
 
    // 處理Key
    err := c.processItem(key.(string))
 
    if err == nil {
        // 處理成功，提示隊列不再跟蹤事件歷史
        c.queue.Forget(key)
    } else if c.queue.NumRequeues(key) < maxRetries {
        glog.Errorf("處理%s事件失敗，准備重試： %v", key, err)
        c.queue.AddRateLimited(key)
    } else {
        glog.Errorf("處理%s事件失敗，放棄： %v", key, err)
        c.queue.Forget(key)
        utilruntime.HandleError(err)
    }
    return true
}
 
// Worker核心邏輯
func (c *Controller) processItem(key string) error {
    glog.Infof("開始處理事件%s", key)
    // 根據Key獲取對象
    obj, exists, err := c.informer.GetIndexer().GetByKey(key)
    if err != nil {
        return fmt.Errorf("獲取對象%s失敗: %v", key, err)
    }
    fmt.Print(obj)
    if !exists {
        // 在這里處理對象刪除事件
    } else {
        // 在這里處理對象創建事件
    }
    // 因為不進行Resync，不會有更新事件
    return nil
}
 
func main() {
    // 解析參數，存入上述變量
    flag.Parse()
    cfg, err := clientcmd.BuildConfigFromFlags(masterURL, kubeconfig)
    if err != nil {
        glog.Fatalf("構建kubeconfig失敗: %s", err.Error())
    }
    // 創建客戶端，Clientset是一系列K8S API的集合
    clientset, err := kubernetes.NewForConfig(cfg)
    if err != nil {
        glog.Fatalf("構建clientset失敗: %s", err.Error())
    }
    // 信號處理通道，當進程接收到信號后，此通道可讀
    stopCh := signals.SetupSignalHandler()
 
    queue := workqueue.NewRateLimitingQueue(workqueue.DefaultControllerRateLimiter())
 
    informer := cache.NewSharedIndexInformer(
        &cache.ListWatch{
            ListFunc: func(options metav1.ListOptions) (runtime.Object, error) {
                // 僅僅列出所有命名空間的Pod
                return clientset.CoreV1().Pods(metav1.NamespaceAll).List(options)
            },
            WatchFunc: func(options metav1.ListOptions) (watch.Interface, error) {
                return clientset.CoreV1().Pods(metav1.NamespaceAll).Watch(options)
            },
        },
        &apiv1.Pod{},
        0,                // 不進行relist
        cache.Indexers{}, // map[string]IndexFunc
    )
 
    // 添加事件處理回調，僅僅是簡單的入隊
    informer.AddEventHandler(cache.ResourceEventHandlerFuncs{// 此結構實現ResourceEventHandler
        AddFunc: func(obj interface{}) {
            // 從對象中抽取Key
            key, err := cache.MetaNamespaceKeyFunc(obj)
            if err == nil {
                queue.Add(key)
            }
        },
        DeleteFunc: func(obj interface{}) {
            key, err := cache.DeletionHandlingMetaNamespaceKeyFunc(obj)
            if err == nil {
                queue.Add(key)
            }
        },
    })
 
    // 構建控制器對象
    ctrl := Controller{
        clientset,
        queue,
        informer,
    }
 
    // 啟動
    ctrl.Run(stopCh)
}