k8s-client实现kubectl
https://github.com/kubernetes/client-go
k8s-client 是对k8s api的一个封装，应用k8s-client 我们可以实现kubectl 所有功能。
通过读取配置文件可以获得kubernetes.Clientset连接，剩下的所有操作都是在kubernetes.Clientset上进行的。
分两种场景
1，在pod之外远程获取*kubernetes.Clientset
func getClient() *kubernetes.Clientset {
kubeconfig := filepath.Join(os.Getenv(“HOME”), “.kube”, “config”)
// BuildConfigFromFlags is a helper function that builds configs from a master url or
// a kubeconfig filepath.
config, err := clientcmd.BuildConfigFromFlags(“”, kubeconfig)
if err != nil {
log.Fatal(err)
}
// NewForConfig creates a new Clientset for the given config.
// https://godoc.org/k8s.io/client-go/kubernetes#NewForConfig
clientset, err := kubernetes.NewForConfig(config)
if err != nil {
log.Fatal(err)
}
return clientset
}
通过解析
~/.kube/config
进行认证，获取*kubernetes.Clientset
2，在pod内部，获取*kubernetes.Clientset
func getInpodClient() (*kubernetes.Clientset, error) {
config, err := rest.InClusterConfig()
if err != nil {
return nil, err
}
clientset, err := kubernetes.NewForConfig(config)
if err != nil {
return nil, err
}
return clientset, nil
}
“k8s.io/client-go/rest”
提供了一个接口来获取pod内部的配置
模拟实现kubectl的功能
1，获取namespace
% kubectl get ns
NAME STATUS AGE
default Active 30d
ingress-nginx Active 27d
kube-node-lease Active 30d
kube-public Active 30d
kube-system Active 30d
kubernetes-dashboard Active 29d
clientset := getClient()
ctx := context.TODO()
nss, err := clientset.CoreV1().Namespaces().List(ctx, metav1.ListOptions{})
for _, n := range nss.Items {
fmt.Println(“ns:”, n.Name)
}
输出
ns: default
ns: ingress-nginx
ns: kube-node-lease
ns: kube-public
ns: kube-system
ns: kubernetes-dashboard
2，获取node
% kubectl get nodes
NAME STATUS ROLES AGE VERSION
docker-desktop Ready master 30d v1.19.7
clientset := getClient()
ctx := context.TODO()
nodes, err := clientset.CoreV1().Nodes().List(ctx, metav1.ListOptions{})
for _, n := range nodes.Items {
fmt.Println(“nodes:”, n.Name)
}
nodes: docker-desktop
3,获取svc
% kubectl get svc -n kube-system
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kube-dns ClusterIP 10.96.0.10
clientset := getClient()
ctx := context.TODO()
svcs, err := clientset.CoreV1().Services(namespace).List(ctx, metav1.ListOptions{})
for _, s := range svcs.Items {
fmt.Println("svc:", s.Name)
}
svc: kube-dns
4,获取pod ip
% kubectl get pod -n kube-system -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
coredns-f9fd979d6-cg26k 1/1 Running 6 30d 10.1.0.85 docker-desktop
coredns-f9fd979d6-dqffw 1/1 Running 6 30d 10.1.0.84 docker-desktop
etcd-docker-desktop 1/1 Running 8 30d 192.168.65.4 docker-desktop
kube-apiserver-docker-desktop 1/1 Running 23 30d 192.168.65.4 docker-desktop
kube-controller-manager-docker-desktop 1/1 Running 6 30d 192.168.65.4 docker-desktop
kube-proxy-fw6rz 1/1 Running 6 30d 192.168.65.4 docker-desktop
kube-scheduler-docker-desktop 1/1 Running 60 30d 192.168.65.4 docker-desktop
storage-provisioner 1/1 Running 78 30d 10.1.0.86 docker-desktop
vpnkit-controller 1/1 Running 6 30d 10.1.0.87 docker-desktop
clientset := getClient()
ctx := context.TODO()
pi := clientset.CoreV1().Pods(namespace)
pods, err := pi.List(ctx, metav1.ListOptions{})
if err != nil {
return nil, err
}
//fmt.Println(pods)
var ips []string
for _, pod := range pods.Items {
ips = append(ips, pod.Status.PodIP)
}
fmt.Println(ips)
[10.1.0.85 10.1.0.84 192.168.65.4 192.168.65.4 192.168.65.4 192.168.65.4 192.168.65.4 10.1.0.86 10.1.0.87]
