启用自动缩放后，GKE不会从0缩放到/从0缩放 [英] GKE does not scale to/from 0 when autoscaling enabled

问题描述

我想在我的GKE上运行CronJob，以便每天执行批处理操作.理想的情况是，当作业未运行时，我的群集可以扩展到0个节点，每次满足计划时，都可以动态扩展到1个节点并在其上运行该作业.

I want to run a CronJob on my GKE in order to perform a batch operation on a daily basis. The ideal scenario would be for my cluster to scale to 0 nodes when the job is not running and to dynamically scale to 1 node and run the job on it every time the schedule is met.

我首先尝试使用在

I am first trying to achieve this by using a simple CronJob found in the kubernetes doc that only prints the current time and terminates.

我首先使用以下命令创建了集群:

I first created a cluster with the following command:

gcloud container clusters create $CLUSTER_NAME \
    --enable-autoscaling \
    --min-nodes 0 --max-nodes 1 --num-nodes 1 \
    --zone $CLUSTER_ZONE

然后，我创建了一个具有以下描述的CronJob:

Then, I created a CronJob with the following description:

apiVersion: batch/v1beta1
kind: CronJob
metadata:
  name: hello
spec:
  schedule: "1 * * * *"
  jobTemplate:
    spec:
      template:
        spec:
          containers:
          - name: hello
            image: busybox
            args:
            - /bin/sh
            - -c
            - date; echo Hello from the Kubernetes cluster
          restartPolicy: Never

该作业计划每小时运行一次，并在终止之前打印当前时间.

The job is scheduled to run every hour and to print the current time before terminating.

第一件事，我想创建具有0个节点的群集，但是设置--num-nodes 0会导致错误.为什么会这样呢?请注意，创建群集后，我可以将群集手动缩小到0个节点.

First thing, I wanted to create the cluster with 0 nodes but setting --num-nodes 0 results in an error. Why is it so? Note that I can manually scale down the cluster to 0 nodes after it has been created.

第二，如果我的集群有0个节点，则不会安排作业，因为集群不会自动扩展到1个节点，而是出现以下错误:

Second, if my cluster has 0 nodes, the job won't be scheduled because the cluster does not scale to 1 node automatically but instead gives the following error:

无法安排广告连播:没有可用的节点来安排广告连播.

Cannot schedule pods: no nodes available to schedule pods.

第三，如果我的集群有1个节点，则作业可以正常运行，但是此后，集群将不会缩减到0个节点，而是保留1个节点.我让群集运行两个连续的作业，但在这两个作业之间没有缩减.我认为一个小时应该足够使群集能够这样做.

Third, if my cluster has 1 node, the job runs normally but after that, the cluster won't scale down to 0 nodes but stay with 1 node instead. I let my cluster run for two successive jobs and it did not scale down in between. I assume one hour should be long enough for the cluster to do so.

我想念什么?

我已经开始使用它并详细说明了我的解决方案

I've got it to work and detailed my solution here.

推荐答案

更新:

注意:从Kubernetes 1.7版本开始，您可以指定一个最小值 您的节点池的大小为零.这使您的节点池可以扩展 如果不需要运行其中的实例，则完全关闭 工作量.

Note: Beginning with Kubernetes version 1.7, you can specify a minimum size of zero for your node pool. This allows your node pool to scale down completely if the instances within aren't required to run your workloads.

https://cloud.google.com/kubernetes-engine /docs/concepts/cluster-autoscaler

旧答案:

不支持将整个集群扩展到0，因为您总是需要至少一个节点用于系统Pod:

Scaling the entire cluster to 0 is not supported, because you always need at least one node for system pods:

请参阅文档

您可以使用一台用于系统Pod的小型计算机创建一个节点池，并使用一台用于运行工作负载的大型计算机创建另一个节点池.这样，第二个节点池可以缩小到0，并且您仍然有运行系统Pod的空间.

You could create one node pool with a small machine for system pods, and an additional node pool with a big machine where you would run your workload. This way the second node pool can scale down to 0 and you still have space to run the system pods.

尝试之后，@ xEc提到:还请注意，在某些情况下，我的节点池无法扩展，例如如果我创建的池的初始大小为0而不是1.

After attempting, @xEc mentions: Also note that there are scenarios in which my node pool wouldn't scale, like if I created the pool with an initial size of 0 instead of 1.

初步建议:

也许您可以使用cron运行微型VM，以扩大集群规模，提交作业(而不是CronJob)，等待其完成然后将其缩小为0?

Perhaps you could run a micro VM, with cron to scale the cluster up, submit a Job (instead of CronJob), wait for it to finish and then scale it back down to 0?

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