client-go的使用及源码分析

本文个人博客地址：http://www.huweihuang.com/article/source-analysis/client-go-source-analysis/

1. client-go简介

1.1 client-go说明

​ client-go是一个调用kubernetes集群资源对象API的客户端，即通过client-go实现对kubernetes集群中资源对象（包括deployment、service、ingress、replicaSet、pod、namespace、node等）的增删改查等操作。大部分对kubernetes进行前置API封装的二次开发都通过client-go这个第三方包来实现。

​ client-go官方文档：https://github.com/kubernetes/client-go

1.2 示例代码

git clone https://github.com/huweihuang/client-go.git
cd client-go
#保证本地HOME目录有配置kubernetes集群的配置文件
go run client-go.go

client-go.go

package main

import (
    "flag"
    "fmt"
    "os"
    "path/filepath"
    "time"

    metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
    "k8s.io/client-go/kubernetes"
    "k8s.io/client-go/tools/clientcmd"
)

func main() {
    var kubeconfig *string
    if home := homeDir(); home != "" {
        kubeconfig = flag.String("kubeconfig", filepath.Join(home, ".kube", "config"), "(optional) absolute path to the kubeconfig file")
    } else {
        kubeconfig = flag.String("kubeconfig", "", "absolute path to the kubeconfig file")
    }
    flag.Parse()
    // uses the current context in kubeconfig
    config, err := clientcmd.BuildConfigFromFlags("", *kubeconfig)
    if err != nil {
        panic(err.Error())
    }
    // creates the clientset
    clientset, err := kubernetes.NewForConfig(config)
    if err != nil {
        panic(err.Error())
    }
    for {
        pods, err := clientset.CoreV1().Pods("").List(metav1.ListOptions{})
        if err != nil {
            panic(err.Error())
        }
        fmt.Printf("There are %d pods in the cluster\n", len(pods.Items))
        time.Sleep(10 * time.Second)
    }
}

func homeDir() string {
    if h := os.Getenv("HOME"); h != "" {
        return h
    }
    return os.Getenv("USERPROFILE") // windows
}

1.3 运行结果

➜ go run client-go.go
There are 9 pods in the cluster
There are 7 pods in the cluster
There are 7 pods in the cluster
There are 7 pods in the cluster
There are 7 pods in the cluster

2. client-go源码分析

client-go源码：https://github.com/kubernetes/client-go

client-go源码目录结构

• The kubernetes package contains the clientset to access Kubernetes API.
• The discovery package is used to discover APIs supported by a Kubernetes API server.
• The dynamic package contains a dynamic client that can perform generic operations on arbitrary Kubernetes API objects.
• The transport package is used to set up auth and start a connection.
• The tools/cache package is useful for writing controllers.

2.1 kubeconfig

kubeconfig = flag.String("kubeconfig", filepath.Join(home, ".kube", "config"), "(optional) absolute path to the kubeconfig file")

获取kubernetes配置文件kubeconfig的绝对路径。一般路径为$HOME/.kube/config。该文件主要用来配置本地连接的kubernetes集群。

config内容如下：

apiVersion: v1
clusters:
- cluster:
    server: http://<kube-master-ip>:8080
  name: k8s
contexts:
- context:
    cluster: k8s
    namespace: default
    user: ""
  name: default
current-context: default
kind: Config
preferences: {}
users: []

2.2 rest.config

通过参数（master的url或者kubeconfig路径）和BuildConfigFromFlags方法来获取rest.Config对象，一般是通过参数kubeconfig的路径。

config, err := clientcmd.BuildConfigFromFlags("", *kubeconfig)

BuildConfigFromFlags函数源码

k8s.io/client-go/tools/clientcmd/client_config.go

// BuildConfigFromFlags is a helper function that builds configs from a master
// url or a kubeconfig filepath. These are passed in as command line flags for cluster
// components. Warnings should reflect this usage. If neither masterUrl or kubeconfigPath
// are passed in we fallback to inClusterConfig. If inClusterConfig fails, we fallback
// to the default config.
func BuildConfigFromFlags(masterUrl, kubeconfigPath string) (*restclient.Config, error) {
    if kubeconfigPath == "" && masterUrl == "" {
        glog.Warningf("Neither --kubeconfig nor --master was specified.  Using the inClusterConfig.  This might not work.")
        kubeconfig, err := restclient.InClusterConfig()
        if err == nil {
            return kubeconfig, nil
        }
        glog.Warning("error creating inClusterConfig, falling back to default config: ", err)
    }
    return NewNonInteractiveDeferredLoadingClientConfig(
        &ClientConfigLoadingRules{ExplicitPath: kubeconfigPath},
        &ConfigOverrides{ClusterInfo: clientcmdapi.Cluster{Server: masterUrl}}).ClientConfig()
}

2.3 clientset

通过*rest.Config参数和NewForConfig方法来获取clientset对象，clientset是多个client的集合，每个client可能包含不同版本的方法调用。

clientset, err := kubernetes.NewForConfig(config)

2.3.1 NewForConfig

NewForConfig函数就是初始化clientset中的每个client。

k8s.io/client-go/kubernetes/clientset.go

// NewForConfig creates a new Clientset for the given config.
func NewForConfig(c *rest.Config) (*Clientset, error) {
    configShallowCopy := *c
    ...
    var cs Clientset
    cs.appsV1beta1, err = appsv1beta1.NewForConfig(&configShallowCopy)
    ...
    cs.coreV1, err = corev1.NewForConfig(&configShallowCopy)
    ...
}

2.3.2 clientset的结构体

k8s.io/client-go/kubernetes/clientset.go

// Clientset contains the clients for groups. Each group has exactly one
// version included in a Clientset.
type Clientset struct {
    *discovery.DiscoveryClient
    admissionregistrationV1alpha1 *admissionregistrationv1alpha1.AdmissionregistrationV1alpha1Client
    appsV1beta1                   *appsv1beta1.AppsV1beta1Client
    appsV1beta2                   *appsv1beta2.AppsV1beta2Client
    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
}

2.3.3 clientset.Interface

clientset实现了以下的Interface，因此可以通过调用以下方法获得具体的client。例如：

pods, err := clientset.CoreV1().Pods("").List(metav1.ListOptions{})

clientset的方法集接口

k8s.io/client-go/kubernetes/clientset.go

type Interface interface {
    Discovery() discovery.DiscoveryInterface
    AdmissionregistrationV1alpha1() admissionregistrationv1alpha1.AdmissionregistrationV1alpha1Interface
    // Deprecated: please explicitly pick a version if possible.
    Admissionregistration() admissionregistrationv1alpha1.AdmissionregistrationV1alpha1Interface
    AppsV1beta1() appsv1beta1.AppsV1beta1Interface
    AppsV1beta2() appsv1beta2.AppsV1beta2Interface
    // Deprecated: please explicitly pick a version if possible.
    Apps() appsv1beta2.AppsV1beta2Interface
    AuthenticationV1() authenticationv1.AuthenticationV1Interface
    // Deprecated: please explicitly pick a version if possible.
    Authentication() authenticationv1.AuthenticationV1Interface
    AuthenticationV1beta1() authenticationv1beta1.AuthenticationV1beta1Interface
    AuthorizationV1() authorizationv1.AuthorizationV1Interface
    // Deprecated: please explicitly pick a version if possible.
    Authorization() authorizationv1.AuthorizationV1Interface
    AuthorizationV1beta1() authorizationv1beta1.AuthorizationV1beta1Interface
    AutoscalingV1() autoscalingv1.AutoscalingV1Interface
    // Deprecated: please explicitly pick a version if possible.
    Autoscaling() autoscalingv1.AutoscalingV1Interface
    AutoscalingV2beta1() autoscalingv2beta1.AutoscalingV2beta1Interface
    BatchV1() batchv1.BatchV1Interface
    // Deprecated: please explicitly pick a version if possible.
    Batch() batchv1.BatchV1Interface
    BatchV1beta1() batchv1beta1.BatchV1beta1Interface
    BatchV2alpha1() batchv2alpha1.BatchV2alpha1Interface
    CertificatesV1beta1() certificatesv1beta1.CertificatesV1beta1Interface
    // Deprecated: please explicitly pick a version if possible.
    Certificates() certificatesv1beta1.CertificatesV1beta1Interface
    CoreV1() corev1.CoreV1Interface
    // Deprecated: please explicitly pick a version if possible.
    Core() corev1.CoreV1Interface
    ExtensionsV1beta1() extensionsv1beta1.ExtensionsV1beta1Interface
    // Deprecated: please explicitly pick a version if possible.
    Extensions() extensionsv1beta1.ExtensionsV1beta1Interface
    NetworkingV1() networkingv1.NetworkingV1Interface
    // Deprecated: please explicitly pick a version if possible.
    Networking() networkingv1.NetworkingV1Interface
    PolicyV1beta1() policyv1beta1.PolicyV1beta1Interface
    // Deprecated: please explicitly pick a version if possible.
    Policy() policyv1beta1.PolicyV1beta1Interface
    RbacV1() rbacv1.RbacV1Interface
    // Deprecated: please explicitly pick a version if possible.
    Rbac() rbacv1.RbacV1Interface
    RbacV1beta1() rbacv1beta1.RbacV1beta1Interface
    RbacV1alpha1() rbacv1alpha1.RbacV1alpha1Interface
    SchedulingV1alpha1() schedulingv1alpha1.SchedulingV1alpha1Interface
    // Deprecated: please explicitly pick a version if possible.
    Scheduling() schedulingv1alpha1.SchedulingV1alpha1Interface
    SettingsV1alpha1() settingsv1alpha1.SettingsV1alpha1Interface
    // Deprecated: please explicitly pick a version if possible.
    Settings() settingsv1alpha1.SettingsV1alpha1Interface
    StorageV1beta1() storagev1beta1.StorageV1beta1Interface
    StorageV1() storagev1.StorageV1Interface
    // Deprecated: please explicitly pick a version if possible.
    Storage() storagev1.StorageV1Interface
}

2.4 CoreV1Client

我们以clientset中的CoreV1Client为例做分析。

通过传入的配置信息rest.Config初始化CoreV1Client对象。

k8s.io/client-go/kubernetes/clientset.go

cs.coreV1, err = corev1.NewForConfig(&configShallowCopy)

2.4.1 corev1.NewForConfig

k8s.io/client-go/kubernetes/typed/core/v1/core_client.go

// NewForConfig creates a new CoreV1Client for the given config.
func NewForConfig(c *rest.Config) (*CoreV1Client, error) {
    config := *c
    if err := setConfigDefaults(&config); err != nil {
        return nil, err
    }
    client, err := rest.RESTClientFor(&config)
    if err != nil {
        return nil, err
    }
    return &CoreV1Client{client}, nil
}

corev1.NewForConfig方法本质是调用了rest.RESTClientFor(&config)方法创建RESTClient对象，即CoreV1Client的本质就是一个RESTClient对象。

2.4.2 CoreV1Client结构体

以下是CoreV1Client结构体的定义：

k8s.io/client-go/kubernetes/typed/core/v1/core_client.go

// CoreV1Client is used to interact with features provided by the  group.
type CoreV1Client struct {
    restClient rest.Interface
}

CoreV1Client实现了CoreV1Interface的接口，即以下方法，从而对kubernetes的资源对象进行增删改查的操作。

k8s.io/client-go/kubernetes/typed/core/v1/core_client.go

//CoreV1Client的方法
func (c *CoreV1Client) ComponentStatuses() ComponentStatusInterface {...}
//ConfigMaps
func (c *CoreV1Client) ConfigMaps(namespace string) ConfigMapInterface {...}
//Endpoints
func (c *CoreV1Client) Endpoints(namespace string) EndpointsInterface {...}
func (c *CoreV1Client) Events(namespace string) EventInterface {...}
func (c *CoreV1Client) LimitRanges(namespace string) LimitRangeInterface {...}
//Namespaces
func (c *CoreV1Client) Namespaces() NamespaceInterface {...}
//Nodes
func (c *CoreV1Client) Nodes() NodeInterface {...}
func (c *CoreV1Client) PersistentVolumes() PersistentVolumeInterface {...}
func (c *CoreV1Client) PersistentVolumeClaims(namespace string) PersistentVolumeClaimInterface {...}
//Pods
func (c *CoreV1Client) Pods(namespace string) PodInterface {...}
func (c *CoreV1Client) PodTemplates(namespace string) PodTemplateInterface {...}
//ReplicationControllers
func (c *CoreV1Client) ReplicationControllers(namespace string) ReplicationControllerInterface {...}
func (c *CoreV1Client) ResourceQuotas(namespace string) ResourceQuotaInterface {...}
func (c *CoreV1Client) Secrets(namespace string) SecretInterface {...}
//Services
func (c *CoreV1Client) Services(namespace string) ServiceInterface {...}
func (c *CoreV1Client) ServiceAccounts(namespace string) ServiceAccountInterface {...}

2.4.3 CoreV1Interface

k8s.io/client-go/kubernetes/typed/core/v1/core_client.go

type CoreV1Interface interface {
    RESTClient() rest.Interface
    ComponentStatusesGetter
    ConfigMapsGetter
    EndpointsGetter
    EventsGetter
    LimitRangesGetter
    NamespacesGetter
    NodesGetter
    PersistentVolumesGetter
    PersistentVolumeClaimsGetter
    PodsGetter
    PodTemplatesGetter
    ReplicationControllersGetter
    ResourceQuotasGetter
    SecretsGetter
    ServicesGetter
    ServiceAccountsGetter
}

CoreV1Interface中包含了各种kubernetes对象的调用接口，例如PodsGetter是对kubernetes中pod对象增删改查操作的接口。ServicesGetter是对service对象的操作的接口。

2.4.4 PodsGetter

以下我们以PodsGetter接口为例分析CoreV1Client对pod对象的增删改查接口调用。

示例中的代码如下：

pods, err := clientset.CoreV1().Pods("").List(metav1.ListOptions{})

CoreV1().Pods()

k8s.io/client-go/kubernetes/typed/core/v1/core_client.go

func (c *CoreV1Client) Pods(namespace string) PodInterface {
    return newPods(c, namespace)
}

newPods()

k8s.io/client-go/kubernetes/typed/core/v1/pod.go

// newPods returns a Pods
func newPods(c *CoreV1Client, namespace string) *pods {
    return &pods{
        client: c.RESTClient(),
        ns:     namespace,
    }
}

CoreV1().Pods()的方法实际上是调用了newPods()的方法，创建了一个pods对象，pods对象继承了rest.Interface接口，即最终的实现本质是RESTClient的HTTP调用。

k8s.io/client-go/kubernetes/typed/core/v1/pod.go

// pods implements PodInterface
type pods struct {
    client rest.Interface
    ns     string
}

pods对象实现了PodInterface接口。PodInterface定义了pods对象的增删改查等方法。

k8s.io/client-go/kubernetes/typed/core/v1/pod.go

// PodInterface has methods to work with Pod resources.
type PodInterface interface {
    Create(*v1.Pod) (*v1.Pod, error)
    Update(*v1.Pod) (*v1.Pod, error)
    UpdateStatus(*v1.Pod) (*v1.Pod, error)
    Delete(name string, options *meta_v1.DeleteOptions) error
    DeleteCollection(options *meta_v1.DeleteOptions, listOptions meta_v1.ListOptions) error
    Get(name string, options meta_v1.GetOptions) (*v1.Pod, error)
    List(opts meta_v1.ListOptions) (*v1.PodList, error)
    Watch(opts meta_v1.ListOptions) (watch.Interface, error)
    Patch(name string, pt types.PatchType, data []byte, subresources ...string) (result *v1.Pod, err error)
    PodExpansion
}

PodsGetter

PodsGetter继承了PodInterface的接口。

k8s.io/client-go/kubernetes/typed/core/v1/pod.go

// PodsGetter has a method to return a PodInterface.
// A group's client should implement this interface.
type PodsGetter interface {
    Pods(namespace string) PodInterface
}

Pods().List()

pods.List()方法通过RESTClient的HTTP调用来实现对kubernetes的pod资源的获取。

k8s.io/client-go/kubernetes/typed/core/v1/pod.go

// List takes label and field selectors, and returns the list of Pods that match those selectors.
func (c *pods) List(opts meta_v1.ListOptions) (result *v1.PodList, err error) {
    result = &v1.PodList{}
    err = c.client.Get().
        Namespace(c.ns).
        Resource("pods").
        VersionedParams(&opts, scheme.ParameterCodec).
        Do().
        Into(result)
    return
}

以上分析了clientset.CoreV1().Pods("").List(metav1.ListOptions{})对pod资源获取的过程，最终是调用RESTClient的方法实现。

2.5 RESTClient

以下分析RESTClient的创建过程及作用。

RESTClient对象的创建同样是依赖传入的config信息。

k8s.io/client-go/kubernetes/typed/core/v1/core_client.go

client, err := rest.RESTClientFor(&config)

2.5.1 rest.RESTClientFor

k8s.io/client-go/rest/config.go

// RESTClientFor returns a RESTClient that satisfies the requested attributes on a client Config
// object. Note that a RESTClient may require fields that are optional when initializing a Client.
// A RESTClient created by this method is generic - it expects to operate on an API that follows
// the Kubernetes conventions, but may not be the Kubernetes API.
func RESTClientFor(config *Config) (*RESTClient, error) {
    ...
    qps := config.QPS
    ...
    burst := config.Burst
    ...
    baseURL, versionedAPIPath, err := defaultServerUrlFor(config)
    ...
    transport, err := TransportFor(config)
    ...
    var httpClient *http.Client
    if transport != http.DefaultTransport {
        httpClient = &http.Client{Transport: transport}
        if config.Timeout > 0 {
            httpClient.Timeout = config.Timeout
        }
    }

    return NewRESTClient(baseURL, versionedAPIPath, config.ContentConfig, qps, burst, config.RateLimiter, httpClient)
}

RESTClientFor函数调用了NewRESTClient的初始化函数。

2.5.2 NewRESTClient

k8s.io/client-go/rest/client.go

// NewRESTClient creates a new RESTClient. This client performs generic REST functions
// such as Get, Put, Post, and Delete on specified paths.  Codec controls encoding and
// decoding of responses from the server.
func NewRESTClient(baseURL *url.URL, versionedAPIPath string, config ContentConfig, maxQPS float32, maxBurst int, rateLimiter flowcontrol.RateLimiter, client *http.Client) (*RESTClient, error) {
    base := *baseURL
    ...
    serializers, err := createSerializers(config)
    ...
    return &RESTClient{
        base:             &base,
        versionedAPIPath: versionedAPIPath,
        contentConfig:    config,
        serializers:      *serializers,
        createBackoffMgr: readExpBackoffConfig,
        Throttle:         throttle,
        Client:           client,
    }, nil
}

2.5.3 RESTClient结构体

以下介绍RESTClient的结构体定义，RESTClient结构体中包含了http.Client，即本质上RESTClient就是一个http.Client的封装实现。

k8s.io/client-go/rest/client.go

// RESTClient imposes common Kubernetes API conventions on a set of resource paths.
// The baseURL is expected to point to an HTTP or HTTPS path that is the parent
// of one or more resources.  The server should return a decodable API resource
// object, or an api.Status object which contains information about the reason for
// any failure.
//
// Most consumers should use client.New() to get a Kubernetes API client.
type RESTClient struct {
    // base is the root URL for all invocations of the client
    base *url.URL
    // versionedAPIPath is a path segment connecting the base URL to the resource root
    versionedAPIPath string

    // contentConfig is the information used to communicate with the server.
    contentConfig ContentConfig

    // serializers contain all serializers for underlying content type.
    serializers Serializers

    // creates BackoffManager that is passed to requests.
    createBackoffMgr func() BackoffManager

    // TODO extract this into a wrapper interface via the RESTClient interface in kubectl.
    Throttle flowcontrol.RateLimiter

    // Set specific behavior of the client.  If not set http.DefaultClient will be used.
    Client *http.Client
}

2.5.4 RESTClient.Interface

RESTClient实现了以下的接口方法：

k8s.io/client-go/rest/client.go

// Interface captures the set of operations for generically interacting with Kubernetes REST apis.
type Interface interface {
    GetRateLimiter() flowcontrol.RateLimiter
    Verb(verb string) *Request
    Post() *Request
    Put() *Request
    Patch(pt types.PatchType) *Request
    Get() *Request
    Delete() *Request
    APIVersion() schema.GroupVersion
}

在调用HTTP方法（Post()，Put()，Get()，Delete() ）时，实际上调用了Verb(verb string)函数。

k8s.io/client-go/rest/client.go

// Verb begins a request with a verb (GET, POST, PUT, DELETE).
//
// Example usage of RESTClient's request building interface:
// c, err := NewRESTClient(...)
// if err != nil { ... }
// resp, err := c.Verb("GET").
//  Path("pods").
//  SelectorParam("labels", "area=staging").
//  Timeout(10*time.Second).
//  Do()
// if err != nil { ... }
// list, ok := resp.(*api.PodList)
//
func (c *RESTClient) Verb(verb string) *Request {
    backoff := c.createBackoffMgr()

    if c.Client == nil {
        return NewRequest(nil, verb, c.base, c.versionedAPIPath, c.contentConfig, c.serializers, backoff, c.Throttle)
    }
    return NewRequest(c.Client, verb, c.base, c.versionedAPIPath, c.contentConfig, c.serializers, backoff, c.Throttle)
}

Verb函数调用了NewRequest方法，最后调用Do()方法实现一个HTTP请求获取Result。

2.6 总结

client-go对kubernetes资源对象的调用，需要先获取kubernetes的配置信息，即$HOME/.kube/config。

整个调用的过程如下：

kubeconfig→rest.config→clientset→具体的client(CoreV1Client)→具体的资源对象(pod)→RESTClient→http.Client→HTTP请求的发送及响应

通过clientset中不同的client和client中不同资源对象的方法实现对kubernetes中资源对象的增删改查等操作，常用的client有CoreV1Client、AppsV1beta1Client、ExtensionsV1beta1Client等。

3. client-go对k8s资源的调用

创建clientset

//获取kubeconfig
kubeconfig = flag.String("kubeconfig", filepath.Join(home, ".kube", "config"), "(optional) absolute path to the kubeconfig file")
//创建config  
config, err := clientcmd.BuildConfigFromFlags("", *kubeconfig)
//创建clientset
clientset, err := kubernetes.NewForConfig(config)
//具体的资源调用见以下例子

3.1 deployment

//声明deployment对象
var deployment *v1beta1.Deployment
//构造deployment对象
//创建deployment
deployment, err := clientset.AppsV1beta1().Deployments(<namespace>).Create(<deployment>)
//更新deployment
deployment, err := clientset.AppsV1beta1().Deployments(<namespace>).Update(<deployment>)
//删除deployment
err := clientset.AppsV1beta1().Deployments(<namespace>).Delete(<deployment.Name>, &meta_v1.DeleteOptions{})
//查询deployment
deployment, err := clientset.AppsV1beta1().Deployments(<namespace>).Get(<deployment.Name>, meta_v1.GetOptions{})
//列出deployment
deploymentList, err := clientset.AppsV1beta1().Deployments(<namespace>).List(&meta_v1.ListOptions{})
//watch deployment
watchInterface, err := clientset.AppsV1beta1().Deployments(<namespace>).Watch(&meta_v1.ListOptions{})

3.2 service

//声明service对象
var service *v1.Service
//构造service对象
//创建service
service, err := clientset.CoreV1().Services(<namespace>).Create(<service>)
//更新service
service, err := clientset.CoreV1().Services(<namespace>).Update(<service>)
//删除service
err := clientset.CoreV1().Services(<namespace>).Delete(<service.Name>, &meta_v1.DeleteOptions{})
//查询service
service, err := clientset.CoreV1().Services(<namespace>).Get(<service.Name>, meta_v1.GetOptions{})
//列出service
serviceList, err := clientset.CoreV1().Services(<namespace>).List(&meta_v1.ListOptions{})
//watch service
watchInterface, err := clientset.CoreV1().Services(<namespace>).Watch(&meta_v1.ListOptions{})

3.3 ingress

//声明ingress对象
var ingress *v1beta1.Ingress
//构造ingress对象
//创建ingress
ingress, err := clientset.ExtensionsV1beta1().Ingresses(<namespace>).Create(<ingress>)
//更新ingress
ingress, err := clientset.ExtensionsV1beta1().Ingresses(<namespace>).Update(<ingress>)
//删除ingress
err := clientset.ExtensionsV1beta1().Ingresses(<namespace>).Delete(<ingress.Name>, &meta_v1.DeleteOptions{})
//查询ingress
ingress, err := clientset.ExtensionsV1beta1().Ingresses(<namespace>).Get(<ingress.Name>, meta_v1.GetOptions{})
//列出ingress
ingressList, err := clientset.ExtensionsV1beta1().Ingresses(<namespace>).List(&meta_v1.ListOptions{})
//watch ingress
watchInterface, err := clientset.ExtensionsV1beta1().Ingresses(<namespace>).Watch(&meta_v1.ListOptions{})

3.4 replicaSet

//声明replicaSet对象
var replicaSet *v1beta1.ReplicaSet
//构造replicaSet对象
//创建replicaSet
replicaSet, err := clientset.ExtensionsV1beta1().ReplicaSets(<namespace>).Create(<replicaSet>)
//更新replicaSet
replicaSet, err := clientset.ExtensionsV1beta1().ReplicaSets(<namespace>).Update(<replicaSet>)
//删除replicaSet
err := clientset.ExtensionsV1beta1().ReplicaSets(<namespace>).Delete(<replicaSet.Name>, &meta_v1.DeleteOptions{})
//查询replicaSet
replicaSet, err := clientset.ExtensionsV1beta1().ReplicaSets(<namespace>).Get(<replicaSet.Name>, meta_v1.GetOptions{})
//列出replicaSet
replicaSetList, err := clientset.ExtensionsV1beta1().ReplicaSets(<namespace>).List(&meta_v1.ListOptions{})
//watch replicaSet
watchInterface, err := clientset.ExtensionsV1beta1().ReplicaSets(<namespace>).Watch(&meta_v1.ListOptions{})

新版的kubernetes中一般通过deployment来创建replicaSet，再通过replicaSet来控制pod。

3.5 pod

//声明pod对象
var pod *v1.Pod
//创建pod
pod, err := clientset.CoreV1().Pods(<namespace>).Create(<pod>)
//更新pod
pod, err := clientset.CoreV1().Pods(<namespace>).Update(<pod>)
//删除pod
err := clientset.CoreV1().Pods(<namespace>).Delete(<pod.Name>, &meta_v1.DeleteOptions{})
//查询pod
pod, err := clientset.CoreV1().Pods(<namespace>).Get(<pod.Name>, meta_v1.GetOptions{})
//列出pod
podList, err := clientset.CoreV1().Pods(<namespace>).List(&meta_v1.ListOptions{})
//watch pod
watchInterface, err := clientset.CoreV1().Pods(<namespace>).Watch(&meta_v1.ListOptions{})

3.6 statefulset

//声明statefulset对象
var statefulset *v1.StatefulSet
//创建statefulset
statefulset, err := clientset.AppsV1().StatefulSets(<namespace>).Create(<statefulset>)
//更新statefulset
statefulset, err := clientset.AppsV1().StatefulSets(<namespace>).Update(<statefulset>)
//删除statefulset
err := clientset.AppsV1().StatefulSets(<namespace>).Delete(<statefulset.Name>, &meta_v1.DeleteOptions{})
//查询statefulset
statefulset, err := clientset.AppsV1().StatefulSets(<namespace>).Get(<statefulset.Name>, meta_v1.GetOptions{})
//列出statefulset
statefulsetList, err := clientset.AppsV1().StatefulSets(<namespace>).List(&meta_v1.ListOptions{})
//watch statefulset
watchInterface, err := clientset.AppsV1().StatefulSets(<namespace>).Watch(&meta_v1.ListOptions{})

​ 通过以上对kubernetes的资源对象的操作函数可以看出，每个资源对象都有增删改查等方法，基本调用逻辑类似。一般二次开发只需要创建deployment、service、ingress三个资源对象即可，pod对象由deployment包含的replicaSet来控制创建和删除。函数调用的入参一般只有NAMESPACE和kubernetesObject两个参数，部分操作有Options的参数。在创建前，需要对资源对象构造数据，可以理解为编辑一个资源对象的yaml文件，然后通过kubectl create -f xxx.yaml来创建对象。

参考文档

https://github.com/kubernetes/client-go