Go 调用 Kubernetes API 的几个简单的 example

云原生 Go Kubernetes API Client-Go cinder-csi-plugin Openstack Cinder

发布时间 : 2022-05-07 10:17

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使用开源项目 client-go 调用 Kubernetes API，是现在go项目的开发中调用Kubernetes的主流方案。下面给几个简单的例子：

创建 KubernetesClient
创建 KubernetesDynamicClient - 动态客户端数据结构更灵活，但是好像支持的kind有限
KubernetesClient 获取deployment列表，获取storageclass列表，获取pvc列表，获取pod列表，创建pod。
通用数据结构使用NewKubernetesDynamicClient创建pod
yaml文件使用NewKubernetesDynamicClient创建pod
使用KubernetesClient创建、更新、删除secret。为了更新Openstack的keystone信息，比如Openstack的租户变了，用户变了，密码变了，可以通过client-go更新Kubernetes中的secret，借助Kubernetes的Openstack CSI插件：cinder-csi-plugin，可以让Kubernetes继续使用keystone变更后的Cinder存储。

创建 KubernetesClient 和 KubernetesDynamicClient

type Config struct {
    Hosts []string
    Token string
}

func NewKubernetesClient(c *Config) (*kubernetes.Clientset, error) {
    var aliveHost string
    aliveHost, err := SelectAliveHost(c.Hosts)
    if err != nil {
        return nil, err
    }
    if !strings.Contains(aliveHost, ":") {
        aliveHost = fmt.Sprintf("%s:%d", aliveHost, constant.ClusterApiServerPort)
    }
    kubeConf := &rest.Config{
        Host:        string(aliveHost),
        BearerToken: c.Token,
        TLSClientConfig: rest.TLSClientConfig{
            Insecure: true,
        },
    }
    client, err := kubernetes.NewForConfig(kubeConf)
    if err != nil {
        return client, errors.Wrap(err, fmt.Sprintf("new kubernetes client with config failed: %v", err))
    }
    return client, nil
}

func NewKubernetesDynamicClient(c *Config) (dynamic.Interface, error) {
    var aliveHost string
    aliveHost, err := SelectAliveHost(c.Hosts)
    if err != nil {
        return nil, err
    }
    if !strings.Contains(aliveHost, ":") {
        aliveHost = fmt.Sprintf("%s:%d", aliveHost, constant.ClusterApiServerPort)
    }
    kubeConf := &rest.Config{
        Host:        string(aliveHost),
        BearerToken: c.Token,
        TLSClientConfig: rest.TLSClientConfig{
            Insecure: true,
        },
    }
    client, err := dynamic.NewForConfig(kubeConf)
    if err != nil {
        return client, errors.Wrap(err, fmt.Sprintf("new kubernetes client with config failed: %v", err))
    }
    return client, nil
}

KubernetesClient 获取deployment列表，获取storageclass列表，获取pvc列表，获取pod列表，创建pod。

config := kubeutil.Config{
    Hosts: service.hosts,
    Token: service.token,
}
clientset, err := kubeutil.NewKubernetesClient(&config)
if err != nil {
    logger.Log.Errorf("get clientset error:%+v, host:%s", err, strings.Join(service.hosts, ","))
    return err
}
deploymentsClient := clientset.AppsV1().Deployments(apiv1.NamespaceDefault)
list, _ := deploymentsClient.List(context.TODO(), metav1.ListOptions{})
for _, d := range list.Items {
    fmt.Printf(" * deployment %s (%d replicas)\n", d.Name, *d.Spec.Replicas)
}

scClient := clientset.StorageV1().StorageClasses()
scList, _ := scClient.List(context.TODO(), metav1.ListOptions{})
for _, d := range scList.Items {
    fmt.Printf(" * sc %v %v\n", d.Name, d.Provisioner)
}

pvcClient := clientset.CoreV1().PersistentVolumeClaims(apiv1.NamespaceDefault)
pvcList, _ := pvcClient.List(context.TODO(), metav1.ListOptions{})
for _, d := range pvcList.Items {
    fmt.Printf(" * pvc %v %v\n", d.Name, d.Status.Capacity)
}

podClient := clientset.CoreV1().Pods(apiv1.NamespaceDefault)
podList, _ := podClient.List(context.TODO(), metav1.ListOptions{})
for _, d := range podList.Items {
    fmt.Printf(" * pod %v %v\n", d.Name, d.Status.PodIP)
}

var pod apiv1.Pod
pod.APIVersion = "v1"
pod.Kind = "Pod"
pod.ObjectMeta = metav1.ObjectMeta{
    Name: "nginx-by-go",
}
containerList := make([]apiv1.Container, 0)
containerList = append(containerList, apiv1.Container{
    Name:            "nginx-by-go",
    Image:           "registry.paas:8087/library/nginx",
    ImagePullPolicy: "IfNotPresent",
})
pod.Spec = apiv1.PodSpec{
    Containers: containerList,
}
podClient.Create(context.TODO(), &pod, metav1.CreateOptions{})

使用NewKubernetesDynamicClient创建pod，和上面的例子对比明显感受到动态客户端的数据的灵活性。接下来的例子更灵活，直接用了yaml文件。

client, err := kubeutil.NewKubernetesDynamicClient(&config)
podRes := schema.GroupVersionResource{Group: "", Version: "v1", Resource: "pods"}
dynamicPod := &unstructured.Unstructured{
    Object: map[string]interface{}{
        "apiVersion": "v1",
        "kind":       "Pod",
        "metadata": map[string]interface{}{
            "name": "nginx",
        },
        "spec": map[string]interface{}{
            "containers": []map[string]interface{}{
                {
                    "image":           "registry.paas:8087/library/nginx",
                    "imagePullPolicy": "IfNotPresent",
                    "name":            "nginx",
                },
            },
        },
    },
}
fmt.Println(dynamicPod)
dynamicPodList, err := client.Resource(podRes).Namespace(apiv1.NamespaceDefault).List(context.TODO(), metav1.ListOptions{})
if err != nil {
    panic(err)
}
for _, d := range dynamicPodList.Items {
    fmt.Printf(" * dynamicPod %s \n", d.GetName())
}
createrResult, err := client.Resource(podRes).Namespace(apiv1.NamespaceDefault).Create(context.TODO(), dynamicPod, metav1.CreateOptions{})
if err != nil {
    return err
}
fmt.Printf("Created deployment %q.\n", createrResult.GetName())

使用NewKubernetesDynamicClient创建pod，该例子和上面的例子明显感受到动态客户端的数据的灵活性

client, err := kubeutil.NewKubernetesDynamicClient(&config)
gvr := schema.GroupVersionResource{Group: "", Version: "v1", Resource: "pods"}
decoder := yaml.NewDecodingSerializer(unstructured.UnstructuredJSONScheme)
obj := &unstructured.Unstructured{}
var gvk schema.GroupVersionKind
yamlData, err := ioutil.ReadFile("resources/simple.yaml")
if _, _, err := decoder.Decode(yamlData, &gvk, obj); err != nil {
    return err
}
utd, err := client.Resource(gvr).Namespace(apiv1.NamespaceDefault).Create(context.TODO(), obj, metav1.CreateOptions{})
if err != nil {
    return err
}
fmt.Println("utd")
fmt.Println(utd)

secret好像动态客户端创建不了，所以使用KubernetesClient创建、更新、删除secret。为了更新Openstack的keystone信息，比如Openstack的租户变了，用户变了，密码变了，可以通过client-go更新Kubernetes中的secret，借助Kubernetes的Openstack CSI插件：cinder-csi-plugin，可以让Kubernetes继续使用keystone变更后的Cinder存储。

func (service *ClusterSCService) TT() error {

    config := kubeutil.Config{
        Hosts: service.hosts,
        Token: service.token,
    }
    clientset, err := kubeutil.NewKubernetesClient(&config)
    if err != nil {
        logger.Log.Errorf("get clientset error:%+v, host:%s", err, strings.Join(service.hosts, ","))
        return err
    }

    secretClient := clientset.CoreV1().Secrets("kube-system")
    secretList, _ := secretClient.List(context.TODO(), metav1.ListOptions{})
    for _, d := range secretList.Items {
        fmt.Printf(" * secret: %v %v\n", d.Name, d.Type)
    }

    var secret apiv1.Secret
    secret.Kind = "Secret"
    secret.APIVersion = "v1"
    secret.ObjectMeta = metav1.ObjectMeta{
        Name:      "cloud-config",
        Namespace: "kube-system",
    }
    dataMap := make(map[string][]byte)
    dataMap["cloud.conf"] = []byte("W0dsb2JhbF0KdXNlcm5hbWUgPSBhZG1pbgpwYXNzd29yZCA9IEFkbWluX1BXRF84NjQ4NjczNTFxc2Myd2R2M2VmYjRyZ24KdGVuYW50LWlkID0gOWEyY2I0MDlmMGRhNDhlMzg1ODY4ZjI3ZmM5YzhjOWIKZG9tYWluLW5hbWUgPSBEZWZhdWx0CmF1dGgtdXJsID0gaHR0cDovL29wZW5zdGFjay1rZXlzdG9uZS12aXA6MzUzNTcvdjMKcmVnaW9uID0gcmVnaW9ub25lCg==")
    secret.Data = dataMap
    fmt.Println(secret)
    result, err := secretClient.Create(context.TODO(), &secret, metav1.CreateOptions{})
    if err != nil {
        fmt.Printf("err ... %v", err)
        return err
    }
    fmt.Printf(" * secret create: %v\n", result)

    result.Data["cloud.conf"] = []byte("hhh")
    fmt.Printf(" * new secret: %v\n", result)
    result, err = secretClient.Update(context.TODO(), result, metav1.UpdateOptions{})
    if err != nil {
        fmt.Printf("err ... %v", err)
        return err
    }
    fmt.Printf(" * secret update: %v\n", result)

    err = secretClient.Delete(context.TODO(), "cloud-config", metav1.DeleteOptions{})
    if err != nil {
        fmt.Printf("err ... %v", err)
        return err
    }

    return nil
}

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Go 调用 Kubernetes API 的 几个简单的 example

Go 调用 Kubernetes API 的几个简单的 example