k8s之client-go：golang与k8s交互的桥梁_业界新闻

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 main import ( "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 = 1 cronJobInfo := 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 }