k8s之client-go：golang与k8s交互的桥梁

前言

k8s是一个非常成熟且强大的容器自动化编排引擎，对于这样一个利器，k8s官方提供了clientgo用来给我们使用golang去接入k8s，通过k8s的api来对k8s中的资源进行操作
通过client-go实现对k8s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

示例

我们通过一个申请K8S中cronjob资源的例子，来举例说明clientgo的使用

package mainimport ("k8s.io/client-go/kubernetes""k8s.io/client-go/rest"metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"v1 "k8s.io/api/core/v1"batchv1 "k8s.io/client-go/applyconfigurations/batch/v1"corev1 "k8s.io/client-go/applyconfigurations/core/v1"
)var cli *kubernetes.Clientset
var config *rest.Config// InitK8SCli 创建clientgo客户端
func InitK8SCli() error {var err error// k8s中的Pod通过这种方式获取配置信息（需要通过给pod绑定角色，通过rbac的权限控制对资源操作的权限）config, err = rest.InClusterConfig()if err != nil {return err}cli, err = kubernetes.NewForConfig(config)if err != nil {return err}return nil
}func main() {err := InitK8SCli()if err != nil {panic(err)}// 成功的job的最大数量var successfulJobsHistoryLimit int32 = 1// 失败的job的最大数量var failedJobsHistoryLimit int32 = 1// job执行完毕之后的存活时间var ttlSecondsAfterFinished int32 = 1cronJobInfo := K8SCronJobInfo{Name:                       "zuimo",Namespace:                  "zuimo",Schedule:                   "* * * * *",Image:                      "busybox",Command:                    []string{"echo", "hello world"},RestartPolicy:              "Never",SuccessfulJobsHistoryLimit: &successfulJobsHistoryLimit,FailedJobsHistoryLimit:     &failedJobsHistoryLimit,TTLSecondsAfterFinished:    &ttlSecondsAfterFinished,}err = ApplyCronJob(cronJobInfo)if err != nil {panic(err)}
}type K8SCronJobInfo struct {Name                       string   `json:"name"`Namespace                  string   `json:"namespace"`Schedule                   string   `json:"schedule"`Image                      string   `json:"image"`Command                    []string `json:"command"`RestartPolicy              string   `json:"restartPolicy"`SuccessfulJobsHistoryLimit *int32   `json:"successfulJobsHistoryLimit"`FailedJobsHistoryLimit     *int32   `json:"failedJobsHistoryLimit"`TTLSecondsAfterFinished    *int32   `json:"ttlSecondsAfterFinished"`
}// 申请cronjob的函数
func ApplyCronJob(cronJobInfo K8SCronJobInfo) error {cronJob := buildCronJob(cronJobInfo)result, err := cli.BatchV1().CronJobs(cronJobInfo.Namespace).Apply(context.Background(), cronJob,metav1.ApplyOptions{FieldManager: "data-manager"})if err != nil {fmt.Printf("cron job obj: %v\n", result)return err}return nil
}// buildCronJob 构造cronjob结构体
func buildCronJob(param K8SCronJobInfo) *batchv1.CronJobApplyConfiguration {container := corev1.Container().WithName(param.Name).WithImage(param.Image).WithImagePullPolicy(v1.PullIfNotPresent).WithCommand(param.Command...)podSpec := corev1.PodSpec().WithContainers(container).WithRestartPolicy(v1.RestartPolicy(param.RestartPolicy))podTemplateSpec := corev1.PodTemplateSpec().WithSpec(podSpec)jobSpec := batchv1.JobSpec().WithTemplate(podTemplateSpec)if param.TTLSecondsAfterFinished != nil {jobSpec = jobSpec.WithTTLSecondsAfterFinished(*param.TTLSecondsAfterFinished)}jobTemplateSpec := batchv1.JobTemplateSpec().WithSpec(jobSpec)cronJobSpec := setJobsHistoryLimit(batchv1.CronJobSpec().WithSchedule(param.Schedule).WithJobTemplate(jobTemplateSpec), param.SuccessfulJobsHistoryLimit, param.FailedJobsHistoryLimit)return batchv1.CronJob(param.Name, param.Namespace).WithSpec(cronJobSpec)
}func setJobsHistoryLimit(cronJobSpec *batchv1.CronJobSpecApplyConfiguration, successfulJobsHistoryLimit,failedJobsHistoryLimit *int32) *batchv1.CronJobSpecApplyConfiguration {if successfulJobsHistoryLimit != nil {cronJobSpec = cronJobSpec.WithSuccessfulJobsHistoryLimit(*successfulJobsHistoryLimit)}if failedJobsHistoryLimit != nil {cronJobSpec = cronJobSpec.WithFailedJobsHistoryLimit(*failedJobsHistoryLimit)}return cronJobSpec
}

总结

我们演示了一个简单的例子，来描述client-go的基本用法，希望对你有所帮助