扩展kubernetes client-go

Question

我正在编写一个控制器来监视kubernetes service对象，并在它们包含某个标签时创建trafficsplits。

由于本地kubernetes go客户端不支持trafficsplit对象，因此我必须找到一种方法并扩展客户端，使其能够识别自定义资源。我发现这个guide很有帮助，让我可以像这样处理这个问题-

import (
    "splitClientV1alpha1 "github.com/servicemeshinterface/smi-sdk-go/pkg/gen/client/split/clientset/versioned/typed/split/v1alpha1"
    "k8s.io/client-go/kubernetes"
    ...
)

// getting ./kube/config from file
kubehome := filepath.Join(homedir.HomeDir(), ".kube", "config")
// Building the config from file
kubeConfig, err = clientcmd.BuildConfigFromFlags("", kubehome)
if err != nil {
    return fmt.Errorf("error loading kubernetes configuration: %w", err)
}

// Creating the native client object
kubeClient, err := kubernetes.NewForConfig(kubeConfig)
if err != nil {
    return fmt.Errorf("error creating kubernetes client: %w", err)
}

// Creating another clientset exclusively for the custom resource
splitClient, err := splitClientV1alpha1.NewForConfig(kubeConfig)
if err != nil {
    return fmt.Errorf("error creating split client: %s", err)
}

我觉得一定有一种方法可以用trafficsplit模式扩展kubeClient对象，而不是像我那样创建一个单独的客户端。有什么方法可以做到这一点吗？

Answer 1

这绝对是可能的！您想要使用go的struct扩展特性:)

因此，我们创建了一个同时扩展kubernetes.Clientset和splitClientV1alpha1.SplitV1alpha1Client的结构，并使用与上面非常相似的代码对其进行初始化。然后，我们可以在该结构上使用来自任一客户端的方法。

import (
    "fmt"
    splitClientV1alpha1 "github.com/servicemeshinterface/smi-sdk-go/pkg/gen/client/split/clientset/versioned/typed/split/v1alpha1"
    "k8s.io/client-go/kubernetes"
    "k8s.io/client-go/tools/clientcmd"
    "k8s.io/client-go/util/homedir"
    "path/filepath"
)

type MyKubeClient struct {
    kubernetes.Clientset
    splitClientV1alpha1.SplitV1alpha1Client
}

func getClient() (*MyKubeClient, error) {
    // getting ./kube/config from file
    kubehome := filepath.Join(homedir.HomeDir(), ".kube", "config")
    // Building the config from file
    kubeConfig, err := clientcmd.BuildConfigFromFlags("", kubehome)
    if err != nil {
        return nil, fmt.Errorf("error loading kubernetes configuration: %w", err)
    }

    // Creating the native client object
    kubeClient, err := kubernetes.NewForConfig(kubeConfig)
    if err != nil {
        return nil, fmt.Errorf("error creating kubernetes client: %w", err)
    }

    // Creating another clientset exclusively for the custom resource
    splitClient, err := splitClientV1alpha1.NewForConfig(kubeConfig)
    if err != nil {
        return nil, fmt.Errorf("error creating split client: %s", err)
    }

    return &MyKubeClient{
        Clientset:           *kubeClient,
        SplitV1alpha1Client: *splitClient,
    }, nil
}

func doSomething() error {
    client, err := getClient()
    if err != nil {
        return err
    }

    client.CoreV1().Pods("").Create(...)
    client.TrafficSplits(...)
}

如果您需要将您的自定义客户端传递给一个只需要原始kubernetes.ClientSet的函数，您可以使用：

func doSomething() error {
    client, err := getClient()
    if err != nil {
        return err
    }

    useClientSet(&client.Clientset)
}

func useOriginalKubeClientSet(clientSet *kubernetes.Clientset) {
    # ... do things
}