定时自动重启 Pod 服务

方法1：滚动重启

从 1.15 版开始，Kubernetes 允许滚动重启 Deployment，这是最快的重启方式：

1	kubectl rollout restart deployment [deployment_name]

该命令会逐步关闭并重启 Deployment 中的每个 Pod 容器，重启过程中应用仍然可用，因为大多数容器仍在运行。

方法2：使用环境变量

通过设置或更改环境变量，可以强制 Pod 重新启动并同步变更。例如，更改容器部署日期：

1	kubectl set env deployment [deployment_name] DEPLOY_DATE="$(date)"

方法3：缩放副本数

使用 scale 命令将副本数设置为 0 来关闭容器：

1	kubectl scale deployment [deployment_name] --replicas=0

再将副本数恢复为大于零的值来重新启动：

1	kubectl scale deployment [deployment_name] --replicas=1

Kubernetes 会销毁旧副本并创建新副本，新副本的名称会与旧副本不同。可以使用 kubectl get pods 查看状态和新名称。

上面通过 kubectl rollout restart 重新启动，Deployment 会创建新的副本并等待它们启动，然后删除旧 Pod 并重新路由流量，服务不会中断。接下来介绍如何使用 CronJob 配合 rollout restart 定时重启 Pod。

方法4：使用cronjob命令配合rollout restart每天定时重启动pod

在开始之前必须先设置RBAC，以便从集群内部运行的Kubernetes client具有对Kubernetes API执行所需调用的权限。

#Service account the client will use to reset the deployment,
#by default the pods running inside the cluster can do no such things.
kind: ServiceAccount
apiVersion: v1
metadata:
  name: deployment-restart
  namespace: <YOUR NAMESPACE>
---
# allow getting status and patching only the one deployment you want
# to restart
apiVersion: rbac.authorization.k8s.io/v1
kind: Role
metadata:
  name: deployment-restart
  namespace: <YOUR NAMESPACE>
rules:
	# if you wanna watch pod resources，add "metrics.k8s.io"
  - apiGroups: ["", "apps", "extensions", "metrics.k8s.io"]
  	# if you wanna execute pod，add "pod/exec"
    resources: ["deployments", "pods", "pods/exec"]
    # ResourceNames is an optional white list of names that the rule applies to. An empty set means that everything is allowed.
    resourceNames: ["<YOUR DEPLOYMENT NAME>"]
    verbs: ["get", "patch", "list", "watch"] # "list" and "watch" are only needed
                                             # if you want to use `rollout status`
---
# bind the role to the service account
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
  name: deployment-restart
  namespace: <YOUR NAMESPACE>
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: Role
  name: deployment-restart
subjects:
  - kind: ServiceAccount
    name: deployment-restart
    namespace: <YOUR NAMESPACE>
---
# cronjob配置:
apiVersion: batch/v1
kind: CronJob
metadata:
  name: deployment-restart
  namespace: <YOUR NAMESPACE>
spec:
  concurrencyPolicy: Forbid
  schedule: '0 8 * * *' # cron spec of time, here, 8 o'clock
  jobTemplate:
    spec:
      backoffLimit: 2 # this has very low chance of failing, as all this does
                      # is prompt kubernetes to schedule new replica set for
                      # the deployment
      activeDeadlineSeconds: 600 # timeout, makes most sense with 
                                 # "waiting for rollout" variant specified below
      template:
        spec:
          serviceAccountName: deployment-restart # name of the service
                                                 # account configured above
          restartPolicy: Never
          containers:
            - name: kubectl
              image: bitnami/kubectl # probably any kubectl image will do,
                                     # optionaly specify version, but this
                                     # should not be necessary, as long the
                                     # version of kubectl is new enough to
                                     # have `rollout restart`
              command:
                - 'kubectl'
                - 'rollout'
                - 'restart'
                - 'deployment/<YOUR DEPLOYMENT NAME>'

如果希望cronjob等待部署完成，可以将cronjob命令更改为:

command:
 - bash
 - -c
 - |-
   kubectl rollout restart deployment/<YOUR DEPLOYMENT NAME> &&
   kubectl rollout status deployment/<YOUR DEPLOYMENT NAME>

以下是一个判断对应服务内存是否超过 1500Mi 并自动重启的示例：

command:
  - bash
  - '-c'
  - |-
    MAX_RESOURCE=1500
    NAME_SPACE=?;
    DEPLOY_NAME=?;
    if [[ $(kubectl top pods -n $NAME_SPACE --selector app=$DEPLOY_NAME | awk 'NR>1 {mem=$3; sub(/Mi/, "", mem); if (mem > $MAX_RESOURCE) {over=1}} END {if (over) {print "WARN"}}') == 'WARN' ]] ; then
      echo "WARN: memory usage over $MAX_RESOURCE"
      kubectl rollout restart deployment -n $NAME_SPACE $DEPLOY_NAME
    fi

补充一个定期删除某 Deployment 下以 upload 开头的文件的指令：

command:
  - bash
  - '-c'
  - |-
    NAME_SPACE=?;
    DEPLOY_NAME=?;
    for pod in $(kubectl get pod -n $NAME_SPACE --selector "app=$DEPLOY_NAME" -o  jsonpath='{.items[*].metadata.name}'); do
      kubectl exec $pod -n $NAME_SPACE -- find /tmp -mtime +1 -name 'upload_*' -type f -print -exec rm -f {} \;
    done