Backgroud
前一章中，对kubernetes的选举原理进行了深度剖析，下面就通过一个example来实现一个，利用kubernetes提供的选举机制完成的高可用应用。
对于此章需要提前对一些概念有所了解后才可以继续看下去
- leader election mechanism
- RBCA
- Pod runtime mechanism
Implementation
代码实现
如果仅仅是使用Kubernetes中的锁，实现的代码也只有几行而已。
[code]package mainimport ( "context" "flag" "fmt" "os" "os/signal" "syscall" "time" metav1 "k8s.io/apimachinery/pkg/apis/meta/v1" clientset "k8s.io/client-go/kubernetes" "k8s.io/client-go/rest" "k8s.io/client-go/tools/clientcmd" "k8s.io/client-go/tools/leaderelection" "k8s.io/client-go/tools/leaderelection/resourcelock" "k8s.io/klog/v2")func buildConfig(kubeconfig string) (*rest.Config, error) { if kubeconfig != "" { cfg, err := clientcmd.BuildConfigFromFlags("", kubeconfig) if err != nil { return nil, err } return cfg, nil } cfg, err := rest.InClusterConfig() if err != nil { return nil, err } return cfg, nil}func main() { klog.InitFlags(nil) var kubeconfig string var leaseLockName string var leaseLockNamespace string var id string // 初始化客户端的部分 flag.StringVar(&kubeconfig, "kubeconfig", "", "absolute path to the kubeconfig file") flag.StringVar(&id, "id", "", "the holder identity name") flag.StringVar(&leaseLockName, "lease-lock-name", "", "the lease lock resource name") flag.StringVar(&leaseLockNamespace, "lease-lock-namespace", "", "the lease lock resource namespace") flag.Parse() if leaseLockName == "" { klog.Fatal("unable to get lease lock resource name (missing lease-lock-name flag).") } if leaseLockNamespace == "" { klog.Fatal("unable to get lease lock resource namespace (missing lease-lock-namespace flag).") } config, err := buildConfig(kubeconfig) if err != nil { klog.Fatal(err) } client := clientset.NewForConfigOrDie(config) run := func(ctx context.Context) { // 实现的业务逻辑，这里仅仅为实验，就直接打印了 klog.Info("Controller loop...") for { fmt.Println("I am leader, I was working.") time.Sleep(time.Second * 5) } } // use a Go context so we can tell the leaderelection code when we // want to step down ctx, cancel := context.WithCancel(context.Background()) defer cancel() // 监听系统中断 ch := make(chan os.Signal, 1) signal.Notify(ch, os.Interrupt, syscall.SIGTERM) go func() { |
