避免在 Kubernetes 中为一个 cron 执行点运行多个 cron 作业

Question

编辑：问题解决了，这是我的错误，我只是使用了错误的 cron 设置。我假设“* 2 * * *”每天仅在 2 点运行一次，但实际上它在 2 小时后每分钟运行一次。因此 Kubernetes 的行为是正确的。

我一直在一个 cron 执行点运行多个作业。但似乎只有这些作业的运行时间很短。知道为什么会发生这种情况以及如何预防吗？我使用concurrencyPolicy: Forbid,backoffLimit: 0和restartPolicy: Never.

应该每天运行一次的 cron 作业的示例，但在其计划运行时间之后运行多次：

job-1554346620                   1/1           11s        4h42m   
job-1554346680                   1/1           11s        4h41m                     
job-1554346740                   1/1           10s        4h40m 

相关配置：

apiVersion: batch/v1beta1
kind: CronJob
metadata:
  name: job
spec:
  schedule: "* 2 * * *"
  concurrencyPolicy: Forbid
  jobTemplate:
    spec:
      template:
        spec:
          containers:
            - name: job
              image: job_image:latest
              command: ["rake", "run_job"]
          restartPolicy: Never
          imagePullSecrets:
            - name: regcred
      backoffLimit: 0

Answer 1

在 k8s 上运行 CronJobs 最常见的问题是：

产生许多消耗所有集群资源的 Pod

设置适当的 CronJob 限制非常重要

如果您不确定自己需要什么 - 只需将此示例作为模板：

apiVersion: batch/v1beta1
kind: CronJob
metadata:
  name: my-first-conjob
  namespace: devenv-admitriev
spec:
  schedule: "*/10 * * * *" # MM HH DD MM WKD -- Minutes, Hour, Day, Month, Weekday (eg. Sun, Mon)
  successfulJobsHistoryLimit: 3 # how many completed jobs should be kept
  failedJobsHistoryLimit: 1 # how many failed jobs should be kept
  suspend: false # Here you can suspend cronjob without deliting it
  concurrencyPolicy: Forbid # Choose Forbid if you don't want concurrent executions of your Job

  # The amount of time that Kubernetes can miss and still start a job.
  # If Kubernetes missed too many job starts (100)
  # then Kubernetes logs an error and doesn’t start any future jobs.
  startingDeadlineSeconds: 300 # if a job hasn't started in this many seconds, skip
  jobTemplate:
    spec:
      parallelism: 1 # How many pods will be instantiated at once.
      completions: 1 # How many containers of the job are instantiated one after the other (sequentially) inside the pod.
      backoffLimit: 3 # Maximum pod restarts in case of failure
      activeDeadlineSeconds: 1800 # Limit the time for which a Job can continue to run
      template:
        spec:
          restartPolicy: Never # If you want to restart - use OnFailure
          terminationGracePeriodSeconds: 30
          containers:
          - name: my-first-conjob
            image: busybox
            command:
              - /bin/sh
            args:
              - -c
              - date; echo sleeping....; sleep 90s; echo exiting...;
            resources:
              requests:
                memory: '128Mi'
              limits:
                memory: '1Gi'

Answer 2

您好，不清楚您的期望是什么 - 调查这个问题，但如果我理解正确，您的意思是不同时运行所有 cronjobs：
1.第一个选项 - 更改其计划时间，
2.第二个选项尝试在您的规范中使用模板其他选项，如 -并行作业- 描述：https ://kubernetes.io/docs/concepts/workloads/controllers/jobs-run-to-completion/

“对于工作队列作业，您必须保留 .spec.completions 未设置，并将 .spec.parallelism 设置为非负整数”

  jobTemplate:
    spec:
      parallelism: 1
      template:

要重新创建此任务，请提供更多详细信息。

此外，对于“作业历史记录”，默认情况下successJobsHistoryLimit和failedJobsHistoryLimit分别设置为3和1。
请访问： https: //kubernetes.io/docs/tasks/job/ 如果您有兴趣，可以在“spec”部分设置限制：

successfulJobsHistoryLimit: 1

failedJobsHistoryLimit: 1

希望这有帮助。