K
Q

how to provide the number of CPUs of a node for a pod

2/12/2020

I would like to put number of CPUs into an env, something like this:

  spec:
    containers:
    - name: test-container
      env:
      - name: NUMBER_OF_CPU
        valueFrom:
          fieldRef:
            fieldPath: spec.node.CPU

with kubectl describe nodes there is an info about the number of CPU of a node:

Addresses:
  InternalIP:  127.0.0.1
  Hostname:    host1
Capacity:
 cpu:                8
 ephemeral-storage:  242791844Ki
 hugepages-1Gi:      0
 hugepages-2Mi:      0
 memory:             16271048Ki
 pods:               110

So how could I pass this information to a pod? Thanks,

-- HiB
kubernetes

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2 Answers

2/13/2020

in the fieldRef only annotations, labels, name and namespace are supported. and only from POD object info, this is called Downward API .

From my tests, this command should work for you:

grep -c ^processor /proc/cpuinfo

It will count the number of lines starting with "processor" in /proc/cpuinfo which equals to the amount shown in kubeclt describe node.

Depending on your use case, you can pass it as ENV or let your app run the command:

❯ k describe node gke-cluster-1
Capacity:
  cpu:                        4
  ephemeral-storage:          98868448Ki
  memory:                     15397584Ki

Yaml:

    spec:
      containers:
      - image: ubuntu
        name: shell-demo-cpu
      env:
      - name: NUMBER_OF_CPU
        value: "grep -c ^processor /proc/cpuinfo"

Then call the variable and run it:

kubectl exec -it shell-demo-cpu -- /bin/bash

root@gke-cluster-1:/# env
NUMBER_OF_CPU=grep -c ^processor /proc/cpuinfo

root@gke-cluster-1:/# $NUMBER_OF_CPU
4

Let me know if it that helps.

-- willrof
Source: StackOverflow
2/12/2020

You need to pass args

apiVersion: v1
kind: Pod
metadata:
  name: cpu-demo
  namespace: cpu-example
spec:
  containers:
  - name: cpu-demo-ctr
    image: vish/stress
    resources:
      limits:
        cpu: "1"
      requests:
        cpu: "0.5"
    args:
    - -cpus
    - "2"

The args section of the configuration file provides arguments for the container when it starts. The -cpus "2" argument tells the Container to attempt to use 2 CPUs.

https://kubernetes.io/docs/tasks/configure-pod-container/assign-cpu-resource/#specify-a-cpu-request-and-a-cpu-limit

-- Mauricio
Source: StackOverflow