15. k8s集群搭建之使用client-go 进行k8s相关操作

by k8s

参考

clientset

1.使用client-go out-of-cluster

2.如果在集群内部可以使用incluster配置，只需要导入"k8s.io/client-go/1.5/rest" 使用config, err := rest.InClusterConfig()

2.需要将kubeconfig文件放到指定位置

package main

import (
	"flag"
	"k8s.io/client-go/1.5/kubernetes"
	"k8s.io/client-go/1.5/pkg/api"
	"k8s.io/client-go/1.5/pkg/api/unversioned"
	"k8s.io/client-go/1.5/pkg/api/v1"
	"k8s.io/client-go/1.5/tools/clientcmd"
	"log"
)

var (
	kubeconfig = flag.String("kubeconfig", "./config", "absolute path to the kubeconfig file")
)

func main() {
	flag.Parse()
	// uses the current context in kubeconfig
	config, err := clientcmd.BuildConfigFromFlags("", *kubeconfig)
	if err != nil {
		panic(err.Error())
	}
	// 创建client set
	clientset, err := kubernetes.NewForConfig(config)
	if err != nil {
		panic(err.Error())
	}
	// 获取现有的pod数量
	pods, err := clientset.Core().Pods("").List(api.ListOptions{})
	check_err(err)
	log.Printf("there are %d pods in cluster\n", len(pods.Items))

	// 创建pod
	pod := new(v1.Pod)
	pod.TypeMeta = unversioned.TypeMeta{Kind: "Pod", APIVersion: "v1"}
	pod.ObjectMeta = v1.ObjectMeta{Name: "testapi", Namespace: "default", Labels: map[string]string{"name": "testapi"}}
	pod.Spec = v1.PodSpec{
		RestartPolicy: v1.RestartPolicyAlways,
		Containers: []v1.Container{
			v1.Container{
				Name:  "testapi",
				Image: "nginx",
				Ports: []v1.ContainerPort{
					v1.ContainerPort{
						ContainerPort: 80,
						Protocol:      v1.ProtocolTCP,
					},
				},
			},
		},
	}
	podname, err := clientset.Core().Pods("default").Create(pod)
	check_err(err)
	log.Printf("pod %s have cretae\n", podname.ObjectMeta.Name)

	// 创建namespace
	ns := new(v1.Namespace)
	ns.TypeMeta = unversioned.TypeMeta{Kind: "NameSpace", APIVersion: "v1"}
	ns.ObjectMeta = v1.ObjectMeta{
		Name: "k8s-test",
	}
	ns.Spec = v1.NamespaceSpec{}
	nsname, err := clientset.Core().Namespaces().Create(ns)
	check_err(err)
	log.Printf("namespace %s have cretae\n", nsname.ObjectMeta.Name)

	// 获取现有的pod数量
	pods, err = clientset.Core().Pods("").List(api.ListOptions{})
	check_err(err)
	log.Printf("there are %d pods in cluster\n", len(pods.Items))

	//根据名称获取pod
	geterpod, err := clientset.Core().Pods("default").Get(podname.ObjectMeta.Name)
	check_err(err)
	// 删除pod
	// 因为关系到时间复杂度 需要加上UID保证唯一性
	err = clientset.Core().Pods("default").Delete(geterpod.ObjectMeta.Name, &api.DeleteOptions{Preconditions: &api.Preconditions{UID: &geterpod.ObjectMeta.UID}})
	check_err(err)
	log.Printf("namespace %s have delete\n", "testapi")

	//根据名称获取namespace
	geternsname, err := clientset.Core().Namespaces().Get(nsname.ObjectMeta.Name)
	check_err(err)

	// 删除namespace
	err = clientset.Core().Namespaces().Delete(geternsname.ObjectMeta.Name, &api.DeleteOptions{Preconditions: &api.Preconditions{UID: &geternsname.ObjectMeta.UID}})
	check_err(err)
	log.Printf("namespace %s have delete\n", geternsname.ObjectMeta.Name)

}

func check_err(err error) {
	if err != nil {
		log.Fatal("got err from apiserver: %s\n", err)
	}
}

dynamicclient

client-go除了提供clientset的连接方式，还提供了dynamic client 和restful api的连接方式与apiserver交互

通过dynamic client可以访问所有资源（包括thirdpartresource所能提供的资源）

package main

import (
	"encoding/json"
	"flag"
	"k8s.io/client-go/1.5/dynamic"
	"k8s.io/client-go/1.5/pkg/api/unversioned"
	"k8s.io/client-go/1.5/pkg/api/v1"
	"k8s.io/client-go/1.5/pkg/runtime"
	"k8s.io/client-go/1.5/pkg/watch"
	"k8s.io/client-go/1.5/rest"
	"k8s.io/client-go/1.5/tools/clientcmd"
	"log"
	"reflect"
)

var (
	kubeconfig = flag.String("kubeconfig", "./config", "absolute path to the kubeconfig file")
)

func main() {
	log.SetFlags(log.Llongfile)
	flag.Parse()
	//获取Config
	config, err := clientcmd.BuildConfigFromFlags("", *kubeconfig)
	if err != nil {
		log.Println(err)
	}
	//指定gv
	gv := &unversioned.GroupVersion{"", "v1"}
	//指定resource
	resource := &unversioned.APIResource{Name: "pods", Namespaced: true}

	//指定GroupVersion
	config.ContentConfig = rest.ContentConfig{GroupVersion: gv}
	//默认的是/api 需要手动指定
	config.APIPath = "/api"
	//创建新的dynamic client
	cl, err := dynamic.NewClient(config)
	if err != nil {
		log.Println(err)
	}

	//根据APIResource获取
	obj, err := cl.Resource(resource, "default").Get("golang")
	if err != nil {
		log.Println(err)
	}
	pod := v1.Pod{}
	b, err := json.Marshal(obj.Object)
	if err != nil {
		log.Println(err)
	}
	json.Unmarshal(b, &pod)
	log.Println(pod.Name)

	//创建pod
	conf := make(map[string]interface{})
	conf = map[string]interface{}{
		"apiVersion": "v1",
		"kind":       "Pod",
		"metadata": map[string]interface{}{
			"name": "golang1",
		},
		"spec": map[string]interface{}{
			"containers": []map[string]interface{}{
				map[string]interface{}{
					"image": "golang",
					"command": []string{
						"sleep",
						"3600",
					},
					"name": "golang1",
				},
			},
		},
	}
	podobj := runtime.Unstructured{Object: conf}
	_, err = cl.Resource(resource, "default").Create(&podobj)
	if err != nil {
		log.Println(err)
	}
	// 删除一个pod,删除资源前最好获取UUID
	cl.Resource(resource, "default").Delete("golang1", &v1.DeleteOptions{})

	// 获取列表
	got, err := cl.Resource(resource, "default").List(&v1.ListOptions{})
	if err != nil {
		log.Println(err)
	}
	js, err := json.Marshal(reflect.ValueOf(got).Elem().Interface())
	if err != nil {
		log.Println(err)
	}
	podlist := v1.PodList{}
	err = json.Unmarshal(js, &podlist)
	if err != nil {
		log.Println(err)
	}
	log.Println(podlist.Items[0].Name)

	// 获取thirdpart resource
	gvthird := &unversioned.GroupVersion{"test.io", "v1"}
	thirdpartresource := &unversioned.APIResource{Name: "podtoservices", Namespaced: true}
	config.ContentConfig = rest.ContentConfig{GroupVersion: gvthird}
	config.APIPath = "/apis"
	clthird, err := dynamic.NewClient(config)
	if err != nil {
		log.Println(err)
	}
	objthird, err := clthird.Resource(thirdpartresource, "default").Get("redis-slave-360xf")
	if err != nil {
		log.Println(err)
	}
	log.Println(objthird)

	//watch一个resource
	watcher, err := clthird.Resource(thirdpartresource, "").Watch(&unversioned.TypeMeta{})
	if err != nil {
		log.Println(err)
	}

	c := watcher.ResultChan()
	for {
		select {
		case e := <-c:
			getptrstring(e)
		}
	}
}

func getptrstring(e watch.Event) {
	v := reflect.ValueOf(e.Object)
	log.Printf("Type: %s --- Obj: %s", e.Type, v.Elem().Interface())
}

restclient

restclient 是dynamic client和clientset的基础，支持json与protobuf，可以访问所有资源，实现对自定义thirdpartresource资源的获取

package main

import (
	"flag"
	"k8s.io/client-go/pkg/api"
	"k8s.io/client-go/pkg/api/v1"
	"k8s.io/client-go/pkg/runtime"
	"k8s.io/client-go/pkg/runtime/schema"
	"k8s.io/client-go/pkg/runtime/serializer"
	"k8s.io/client-go/rest"
	"k8s.io/client-go/tools/clientcmd"
	"log"
)

func main() {
	log.SetFlags(log.Llongfile)
	kubeconfig := flag.String("kubeconfig", "./config", "Path to a kube config. Only required if out-of-cluster.")
	flag.Parse()
	config, err := clientcmd.BuildConfigFromFlags("", *kubeconfig)
	if err != nil {
		log.Fatalln(err)
	}
	groupversion := schema.GroupVersion{
		Group:   "k8s.io",
		Version: "v1",
	}
	config.GroupVersion = &groupversion
	config.APIPath = "/apis"
	config.ContentType = runtime.ContentTypeJSON
	config.NegotiatedSerializer = serializer.DirectCodecFactory{CodecFactory: api.Codecs}
	restclient, err := rest.RESTClientFor(config)
	if err != nil {
		log.Fatalln(err)
	}
	e := examples{}
	err = restclient.Get().
		Resource("examples").
		Namespace("default").
		Name("example1").
		Do().Into(&e)
	log.Println(e)
}