kubernetes 是什麼？
Kubernetes是容器叢集管理系統，是一個開源的平台，可以實作容器叢集的自動化部署、自動擴縮容、維護等功能。官方位址
client-go 又是什麼？
client-go是一個調用kubernetes叢集資源對象API的用戶端，即通過client-go實作對kubernetes叢集中資源對象（包括deployment、service、ingress、replicaSet、pod、namespace、node等）的增删改查等操作。大部分對kubernetes進行前置API封裝的二次開發都通過client-go這個第三方包來實作。
github 位址
如何實作deployment 管理的呢？
1、 建立clientset
ClientSet 是一個負責通路k8s叢集 apiserver 的用戶端。裡面包含了各版本的api-group。
// Clientset contains the clients for groups. Each group has exactly one
// version included in a Clientset.
type Clientset struct {
*discovery.DiscoveryClient
admissionregistrationV1beta1 *admissionregistrationv1beta1.AdmissionregistrationV1beta1Client
appsV1 *appsv1.AppsV1Client
appsV1beta1 *appsv1beta1.AppsV1beta1Client
appsV1beta2 *appsv1beta2.AppsV1beta2Client
auditregistrationV1alpha1 *auditregistrationv1alpha1.AuditregistrationV1alpha1Client
authenticationV1 *authenticationv1.AuthenticationV1Client
authenticationV1beta1 *authenticationv1beta1.AuthenticationV1beta1Client
authorizationV1 *authorizationv1.AuthorizationV1Client
authorizationV1beta1 *authorizationv1beta1.AuthorizationV1beta1Client
autoscalingV1 *autoscalingv1.AutoscalingV1Client
autoscalingV2beta1 *autoscalingv2beta1.AutoscalingV2beta1Client
autoscalingV2beta2 *autoscalingv2beta2.AutoscalingV2beta2Client
batchV1 *batchv1.BatchV1Client
batchV1beta1 *batchv1beta1.BatchV1beta1Client
batchV2alpha1 *batchv2alpha1.BatchV2alpha1Client
certificatesV1beta1 *certificatesv1beta1.CertificatesV1beta1Client
coordinationV1beta1 *coordinationv1beta1.CoordinationV1beta1Client
coordinationV1 *coordinationv1.CoordinationV1Client
coreV1 *corev1.CoreV1Client
eventsV1beta1 *eventsv1beta1.EventsV1beta1Client
extensionsV1beta1 *extensionsv1beta1.ExtensionsV1beta1Client
networkingV1 *networkingv1.NetworkingV1Client
networkingV1beta1 *networkingv1beta1.NetworkingV1beta1Client
nodeV1alpha1 *nodev1alpha1.NodeV1alpha1Client
nodeV1beta1 *nodev1beta1.NodeV1beta1Client
policyV1beta1 *policyv1beta1.PolicyV1beta1Client
rbacV1 *rbacv1.RbacV1Client
rbacV1beta1 *rbacv1beta1.RbacV1beta1Client
rbacV1alpha1 *rbacv1alpha1.RbacV1alpha1Client
schedulingV1alpha1 *schedulingv1alpha1.SchedulingV1alpha1Client
schedulingV1beta1 *schedulingv1beta1.SchedulingV1beta1Client
schedulingV1 *schedulingv1.SchedulingV1Client
settingsV1alpha1 *settingsv1alpha1.SettingsV1alpha1Client
storageV1beta1 *storagev1beta1.StorageV1beta1Client
storageV1 *storagev1.StorageV1Client
storageV1alpha1 *storagev1alpha1.StorageV1alpha1Client
}
// 解析config
config, err := clientcmd.BuildConfigFromFlags("", *kubeconfig)
if err != nil {
panic(err.Error())
}
// 建立連接配接
clientset, err := kubernetes.NewForConfig(config)
if err != nil {
panic(err.Error())
}
kubeconfig參數為clientset 要是使用的config檔案，裡面描述了cluster位址，current 使用者資訊（有哪些權限），預設namespace等相關參數，這樣clientset就擁有了kubeconfig的使用者權限。
注： kuberconfig 預設路徑 ~/.kube./config （記錄了目前登陸使用者的資訊）
2、deployment 相關api 接口
// DeploymentInterface has methods to work with Deployment resources.
type DeploymentInterface interface {
Create(*v1beta1.Deployment) (*v1beta1.Deployment, error)
Update(*v1beta1.Deployment) (*v1beta1.Deployment, error)
UpdateStatus(*v1beta1.Deployment) (*v1beta1.Deployment, error)
Delete(name string, options *v1.DeleteOptions) error
DeleteCollection(options *v1.DeleteOptions, listOptions v1.ListOptions) error
Get(name string, options v1.GetOptions) (*v1beta1.Deployment, error)
List(opts v1.ListOptions) (*v1beta1.DeploymentList, error)
Watch(opts v1.ListOptions) (watch.Interface, error)
Patch(name string, pt types.PatchType, data []byte, subresources ...string) (result *v1beta1.Deployment, err error)
DeploymentExpansion
}
上面描述了deployment 相關所有接口，包括Create()，Update()，updateStatus()，Delete()，DeleteCollection()，Get()，List()，Watch()，Patch()。
3、通過api接口，操作deployment 資源
3.1、構造deployment 執行個體
deployment := &v1beta1.Deployment{
ObjectMeta: metav1.ObjectMeta{
Name: "demo-deployment", // 指定 deployment 名字
},
Spec: appsv1.DeploymentSpec{
Replicas: int32Ptr(2), // 指定副本數
Selector: &metav1.LabelSelector{ // 指定标簽
MatchLabels: map[string]string{
"app": "demo",
},
},
Template: apiv1.PodTemplateSpec{ // 容器模闆
ObjectMeta: metav1.ObjectMeta{
Labels: map[string]string{
"app": "demo",
},
},
Spec: apiv1.PodSpec{
...
},
},
},
}
其實上述結構資訊，就是通指令行建立（kubectl apply -f yaml）時，yaml 描述檔案裡的資訊。
3.2 向 apiserver 發送請求，對deployment進行操作
//建立
_,err = cli.AppsV1beta1().Deployments(application.Namespace).Create(&kubeDeployment)
if err != nil{
panic(err.Error())
}
namespace 指定建立在哪個namespace下
//删除
_,err = cli.ExtensionsV1beta1().Deployments(namespace).Delete(name, &metav1.DeleteOptions{})
if err != nil{
panic(err.Error())
}
//更新
_,err = cli.AppsV1beta1().Deployments(deployment.Namespace).Update(old)
if err != nil{
panic(err.Error())
}
//查詢
_,err = cli.AppsV1beta1().Deployments(deployment.Namespace).get(&metav1.DeleteOptions{})
if err != nil{
panic(err.Error())
}
通過以上幾個接口，就可以基本完成對deployment 的管理了，那麼如何實時擷取deployment 資源的變化呢？可以通過上面的watch 接口監聽，client-go提供了一個更進階的接口，informer，後續在詳細讨論
3.3 查詢deployment 下 pod 和 container 狀态
func GetDeploymentDetail(deployment *v1beta1.Deployment, indexer *client.CacheFactory) ([]Deployment, error) {
pods, err := indexer.PodLister().Pods(deployment.Namespace).List(labels.SelectorFromSet(deployment.Spec.Template.Labels))
if err != nil {
logs.Error("get pod list err")
return nil, err
}
deployments := make([]Deployment,0)
for _, pod := range pods {
deployments = append(deployments, Deployment{
Name: pod.Name,
Namespace: pod.Namespace,
Status: string(pod.Status.Phase),
Node: pod.Spec.NodeName,
Labels: pod.Labels,
Containers: toContainer(pod),
})
}
return deployments,nil
}
func GetContainers(pod *v1.Pod) []Container {
ret := make([]Container,0)
containers := pod.Spec.Containers
for i, index := range containers {
ret = append(ret,Container{
Name: index.Name,
Image: index.Image,
State: pod.Status.ContainerStatuses[i].State,
})
}
return ret
}
查詢deployment 關聯pod 和 container相關操作，其實就是pod 的list 接口，通過label篩選。
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