如何安排Pod重新启动

Question

是否可以根据时间自动重启Pod？

例如，我想每天早上8:00 AM重新启动集群的容器。

Answer 1

使用 cronjob，但不是运行 Pod，而是安排 Kubernetes API 命令，该命令将每天重新启动部署 ( kubectl rollout restart)。这样，如果出现问题，旧的 pod 将不会被关闭或移除。

Rollouts 创建新的 ReplicaSets，并等待它们启动，然后杀死旧的 pod，并重新路由流量。服务将继续不间断。

您必须设置 RBAC，以便从集群内部运行的 Kubernetes 客户端有权对 Kubernetes API 进行所需的调用。

---
# 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:
  - apiGroups: ["apps", "extensions"]
    resources: ["deployments"]
    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>

和 cronjob 规范本身：

apiVersion: batch/v1beta1
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>'

或者，如果您希望 cronjob 等待部署推出，请将 cronjob 命令更改为：

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

Answer 2

我借用了 @Ryan Lowe的想法，但做了一些修改。它将重新启动超过 24 小时的 Pod

      livenessProbe:
        exec:
          command:
             - bin/sh
            - -c
            - "end=$(date -u +%s);start=$(stat -c %Z /proc/1 | awk '{print int($1)}'); test $(($end-$start)) -lt 86400"

Answer 3

Another quick and dirty option for a pod that has a restart policy of Always (which cron jobs are not supposed to handle - see creating a cron job spec pod template) is a livenessProbe that simply tests the time and restarts the pod on a specified schedule

ex. After startup, wait an hour, then check hour every minute, if hour is 3(AM) fail probe and restart, otherwise pass

livenessProbe:
  exec:
    command:
    - exit $(test $(date +%H) -eq 3 && echo 1 || echo 0)
  failureThreshold: 1
  initialDelaySeconds: 3600
  periodSeconds: 60

Time granularity is up to how you return the date and test ;)

Of course this does not work if you are already utilizing the liveness probe as an actual liveness probe ¯\_(?)_/¯

Answer 4

有一个特定的资源：CronJob

这里有一个例子：

apiVersion: batch/v1beta1
kind: CronJob
metadata:
  name: your-cron
spec:
  schedule: "*/20 8-19 * * 1-5"
  concurrencyPolicy: Forbid
  jobTemplate:
    spec:
      template:
        metadata:
          labels:
            app: your-periodic-batch-job
        spec:
          containers:
          - name: my-image
            image: your-image
            imagePullPolicy: IfNotPresent
          restartPolicy: OnFailure

如果要在启动新 Pod 时替换旧 Pod，请更改spec.concurrencyPolicy为Replace。使用Forbid，如果旧 Pod 仍在运行，则新 Pod 的创建将被跳过。