说明
kubernetes 估计会成为 linux 一样的存在，client-go 是它的 go sdk，client-go/examples/ 给出了一些用例，但是数量比较少。
api
Resource 的定义不在client-go中，而是在一个名为 api 的项目中，这个项目中的内容同步自 kubernetes 项目的目录 staging/src/k8s.io/api，可以用下面的方式获取：
go get k8s.io/api
api的目录结构如下：
▾ api/
▸ admission/
▸ admissionregistration/
▸ apps/
▸ authentication/
▸ authorization/
▸ autoscaling/
▸ batch/
▸ certificates/
▸ core/
▸ extensions/
▸ Godeps/
▸ imagepolicy/
▸ networking/
▸ policy/
▸ rbac/
▸ scheduling/
▸ settings/
▸ storage/
▸ vendor/
LICENSE
OWNERS
README.md
client-go
client-go是kubernetes官方的项目，go语言实现，使用示例源码位于: go-code-example/k8sclient。
获取 client-go:
go get k8s.io/client-go
go get k8s.io/apimachinery
go get k8s.io/api
go get k8s.io/kube-openapi
创建 Clientset
Clientset 包含 kubernetes 的所有资源的操作句柄，通过”k8s.io/client-go/kubernetes”中NewForConfig()创建。
创建 Clientset 需要提供一个 rest.Config，Config 可以用后面提到的 tools/clientcmd 生成，也可以自己填写：
config := rest.Config{ Host: "https://10.39.0.105:6443", APIPath: "/", Prefix: "", BearerToken: "af8cbdf725efadf8c4", TLSClientConfig: rest.TLSClientConfig{Insecure: true}, }创建方法很简单：
clientset, err := kubernetes.NewForConfig(&config)使用 Clientset
Clientset，意如其名，是client 的集合，在client-go/kubernetes/clientset.go中定义。
type Clientset struct { *discovery.DiscoveryClient admissionregistrationV1alpha1 *admissionregistrationv1alpha1.AdmissionregistrationV1alpha1Client appsV1beta1 *appsv1beta1.AppsV1beta1Client appsV1beta2 *appsv1beta2.AppsV1beta2Client appsV1 *appsv1.AppsV1Client authenticationV1 *authenticationv1.AuthenticationV1Client authenticationV1beta1 *authenticationv1beta1.AuthenticationV1beta1Client authorizationV1 *authorizationv1.AuthorizationV1Client authorizationV1beta1 *authorizationv1beta1.AuthorizationV1beta1Client autoscalingV1 *autoscalingv1.AutoscalingV1Client autoscalingV2beta1 *autoscalingv2beta1.AutoscalingV2beta1Client batchV1 *batchv1.BatchV1Client batchV1beta1 *batchv1beta1.BatchV1beta1Client batchV2alpha1 *batchv2alpha1.BatchV2alpha1Client certificatesV1beta1 *certificatesv1beta1.CertificatesV1beta1Client coreV1 *corev1.CoreV1Client extensionsV1beta1 *extensionsv1beta1.ExtensionsV1beta1Client networkingV1 *networkingv1.NetworkingV1Client policyV1beta1 *policyv1beta1.PolicyV1beta1Client rbacV1 *rbacv1.RbacV1Client rbacV1beta1 *rbacv1beta1.RbacV1beta1Client rbacV1alpha1 *rbacv1alpha1.RbacV1alpha1Client schedulingV1alpha1 *schedulingv1alpha1.SchedulingV1alpha1Client settingsV1alpha1 *settingsv1alpha1.SettingsV1alpha1Client storageV1beta1 *storagev1beta1.StorageV1beta1Client storageV1 *storagev1.StorageV1Client }用 Clientset 的方法获得不同资源的操作句柄，Clientset有以下的方法可供使用：
+Admissionregistration() : admissionregistrationv1alpha1.AdmissionregistrationV1alpha1Interface
+AdmissionregistrationV1alpha1() : admissionregistrationv1alpha1.AdmissionregistrationV1alpha1Interface +Apps() : appsv1.AppsV1Interface +AppsV1() : appsv1.AppsV1Interface +AppsV1beta1() : appsv1beta1.AppsV1beta1Interface +AppsV1beta2() : appsv1beta2.AppsV1beta2Interface +Authentication() : authenticationv1.AuthenticationV1Interface +AuthenticationV1() : authenticationv1.AuthenticationV1Interface +AuthenticationV1beta1() : authenticationv1beta1.AuthenticationV1beta1Interface +Authorization() : authorizationv1.AuthorizationV1Interface +AuthorizationV1() : authorizationv1.AuthorizationV1Interface +AuthorizationV1beta1() : authorizationv1beta1.AuthorizationV1beta1Interface +Autoscaling() : autoscalingv1.AutoscalingV1Interface +AutoscalingV1() : autoscalingv1.AutoscalingV1Interface +AutoscalingV2beta1() : autoscalingv2beta1.AutoscalingV2beta1Interface +Batch() : batchv1.BatchV1Interface +BatchV1() : batchv1.BatchV1Interface +BatchV1beta1() : batchv1beta1.BatchV1beta1Interface +BatchV2alpha1() : batchv2alpha1.BatchV2alpha1Interface +Certificates() : certificatesv1beta1.CertificatesV1beta1Interface +CertificatesV1beta1() : certificatesv1beta1.CertificatesV1beta1Interface +Core() : corev1.CoreV1Interface +CoreV1() : corev1.CoreV1Interface +Discovery() : discovery.DiscoveryInterface +Extensions() : extensionsv1beta1.ExtensionsV1beta1Interface +ExtensionsV1beta1() : extensionsv1beta1.ExtensionsV1beta1Interface +Networking() : networkingv1.NetworkingV1Interface +NetworkingV1() : networkingv1.NetworkingV1Interface +Policy() : policyv1beta1.PolicyV1beta1Interface +PolicyV1beta1() : policyv1beta1.PolicyV1beta1Interface +Rbac() : rbacv1.RbacV1Interface +RbacV1() : rbacv1.RbacV1Interface +RbacV1alpha1() : rbacv1alpha1.RbacV1alpha1Interface +RbacV1beta1() : rbacv1beta1.RbacV1beta1Interface +Scheduling() : schedulingv1alpha1.SchedulingV1alpha1Interface +SchedulingV1alpha1() : schedulingv1alpha1.SchedulingV1alpha1Interface +Settings() : settingsv1alpha1.SettingsV1alpha1Interface +SettingsV1alpha1() : settingsv1alpha1.SettingsV1alpha1Interface +Storage() : storagev1.StorageV1Interface +StorageV1() : storagev1.StorageV1Interface +StorageV1beta1() : storagev1beta1.StorageV1beta1Interface 其中Core()和CoreV1()获取到的corev1.CoreV1Interface，用来操作kubernetes的最基础的Resrouce。
type CoreV1Interface interface { RESTClient() rest.Interface ComponentStatusesGetter ConfigMapsGetter EndpointsGetter EventsGetter LimitRangesGetter NamespacesGetter NodesGetter PersistentVolumesGetter PersistentVolumeClaimsGetter PodsGetter PodTemplatesGetter ReplicationControllersGetter ResourceQuotasGetter SecretsGetter ServicesGetter ServiceAccountsGetter }例如查找指定 namespace 中的所有 Pod：
pods, err := clientset.CoreV1().Pods("lijiaocn").List(v1.ListOptions{})创建 RESTClient
client-go/rest 实现了 RESTClient，RESTClient 的创建方法有两种。
第一种方式是直接通过 config 创建，这种方式需要在 config 中填入 GroupVersion 信息：
// create restClient from config
func CreateCoreRestClient(config *rest.Config) (*rest.RESTClient, error) { config.ContentConfig.GroupVersion = &core_v1.SchemeGroupVersion config.ContentConfig.NegotiatedSerializer = serializer.DirectCodecFactory{CodecFactory: scheme.Codecs} config.APIPath = "/api" restClient, err := rest.RESTClientFor(config) if err != nil { return nil, err } if restClient == nil { return nil, errors.New("restclient1 is nil") } return restClient, nil }第二种方式是从 Clientset 中获取，这种方式不需要手动填入 GroupVersion，调用 Clientset 对应的接口即可：
// get restClient from clientset
func GetCoreRestClient(config *rest.Config) (rest.Interface, error) { clientset, err := kubernetes.NewForConfig(config) if err != nil { return nil, err } if clientset == nil { return nil, errors.New("clientset is nil") } restClient := clientset.CoreV1().RESTClient() if restClient == nil { return nil, errors.New("restclient is nil") } return restClient, nil }使用 RESTClient
RESTClient 是链式调用，使用方法如下，Do() 方法最后调用：
// /<namespace>/<resource>/<name>
// GET https://10.10.173.203/api/v1/namespaces/default/pods?limit=500
// GET https://10.10.173.203/api/v1/namespaces/kube-system/pods?limit=500 // GET https://10.10.173.203/api/v1/namespaces/kube-system/pods/kube-dns-5b54cf547c-jl4r9 result := restClient.Get(). Namespace("kube-system"). Resource("pods"). Name("kube-dns-5b54cf547c-jl4r9"). Do() bytes, err := result.Raw() if err != nil { fmt.Printf("%s: %s\n", err.Error(), bytes) } else { fmt.Printf("%s\n", bytes) }client-go/tools
client-go 提供一套 tools，提供了配置文件加载、实现本地缓存等方法。
tools/clientcmd: 加载配置
tools/clientcmd 中提供了一些辅助工具，例如加载 kubeconfig 文件生成创建 client 是必须的 Config：
home, err := os.UserHomeDir() if err != nil { glog.Fatal(err.Error()) } file, err := filepath.Abs(home + "/.kube/config") if err != nil { glog.Fatal(err.Error()) } config, err := clientcmd.BuildConfigFromFlags("", file) if err != nil { glog.Fatal(err.Error()) return } clientset, err := kubernetes.NewForConfig(config) if err != nil { glog.Fatal(err.Error()) return }tools/cache: 本地缓存
tools/cache 中提供了本地缓存的功能，特别是提供了 informer。
创建 informer 需要提供的 listwatcher 和 handler 都用 cache 中方法创建或在 cache 中定义：
labels := make(map[string]string) selector := fields.SelectorFromSet(labels) listwatch := cache.NewListWatchFromClient(restClient, "endpoints", "", selector)handler 定义：
handler := cache.ResourceEventHandlerFuncs{ AddFunc: func(obj interface{}) { fmt.Printf("Add endpoint:\n") if ep, ok := obj.(*core_v1.Endpoints); !ok { fmt.Printf("not endpoints\n") } else { printEndpoint(ep) } }, UpdateFunc: func(oldObj, newObj interface{}) { fmt.Printf("Update endpoint:\n") if epOld, ok := oldObj.(*core_v1.Endpoints); !ok { fmt.Printf("not endpoints\n") } else { printEndpoint(epOld) } if epNew, ok := newObj.(*core_v1.Endpoints); !ok { fmt.Printf("not endpoints\n") } else { printEndpoint(epNew) } }, DeleteFunc: func(obj interface{}) { fmt.Printf("Delete endpoint:\n") if ep, ok := obj.(*core_v1.Endpoints); !ok { fmt.Printf("not endpoint")