kubernetes 开发入门之获取pod信息
程序员文章站
2022-07-13 22:23:52
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之前写了很多kubernetes源码阅读的文章,今天介绍一下kubernetes开发入门,kubernetes提供了一个client-go,它里面封装了kubernetes的相关操作,分为两种情况,在集群内核集群之外
先说一下集群内
package main
import (
"fmt"
"time"
metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
"k8s.io/client-go/kubernetes"
"k8s.io/client-go/rest"
)
func main() {
// creates the in-cluster config
config, err := rest.InClusterConfig()
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)
}
}
代码很简单,其实是通过kubernetes自身的服务发现去完成的,kubernetes自带的service;访问token也通过secret的方式注入到容器里面,这样容器里面就可以调用kubernetes的api了。
如果是集群之外去访问的话就只能通过kubeconfig文件了。
package main
import (
"flag"
"fmt"
"time"
metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
"k8s.io/apimachinery/pkg/fields"
"k8s.io/client-go/kubernetes"
"k8s.io/client-go/tools/cache"
"k8s.io/client-go/pkg/api/v1"
"k8s.io/client-go/tools/clientcmd"
// Uncomment the following line to load the gcp plugin (only required to authenticate against GKE clusters).
// _ "k8s.io/client-go/plugin/pkg/client/auth/gcp"
)
func main() {
kubeconfig := flag.String("kubeconfig", "/mnt/go/src/k8s.io/client-go/examples/out-of-cluster/config", "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())
}
watchlist := cache.NewListWatchFromClient(clientset.Core().RESTClient(), "pods", v1.NamespaceDefault,
fields.Everything())
_, controller := cache.NewInformer(
watchlist,
&v1.Pod{},
time.Second * 0,
cache.ResourceEventHandlerFuncs{
AddFunc: func(obj interface{}) {
fmt.Printf("add: %s \n", obj)
},
DeleteFunc: func(obj interface{}) {
fmt.Printf("delete: %s \n", obj)
},
UpdateFunc:func(oldObj, newObj interface{}) {
fmt.Printf("old: %s, new: %s \n", oldObj, newObj)
},
},
)
stop := make(chan struct{})
go controller.Run(stop)
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)
}
}
上面代码通过kubeconfig建立连接,通过watchlist的方式监听pods的变化,监听add/delete/update事件。
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