Red Hat OpenShift Container Platform

Scheduling Pods with container resource requests

You can specify CPU and memory resource requests and limits for containers to ensure that pods are placed on nodes with sufficient capacity, preventing resource shortages.

Although memory or CPU resource usage on nodes is very low, the scheduler might still refuse to place a Pod on a node if the capacity check fails to protect against a resource shortage on a node.

For each container, you can specify the following resource limits and request:

spec.containers[].resources.limits.cpu
spec.containers[].resources.limits.memory
spec.containers[].resources.limits.hugepages-<size>
spec.containers[].resources.requests.cpu
spec.containers[].resources.requests.memory
spec.containers[].resources.requests.hugepages-<size>

Although you can specify requests and limits for only individual containers, it is also useful to consider the overall resource requests and limits for a pod. For a particular resource, a container resource request or limit is the sum of the resource requests or limits of that type for each container in the pod.

Example container resource requests and limits

apiVersion: v1
kind: Pod
metadata:
  name: frontend
spec:
  securityContext:
    runAsNonRoot: true
    seccompProfile:
      type: RuntimeDefault
  containers:
  - name: app
    image: images.my-company.example/app:v4
    resources:
      requests:
        memory: "64Mi"
        cpu: "250m"
      limits:
        memory: "128Mi"
        cpu: "500m"
    securityContext:
      allowPrivilegeEscalation: false
      capabilities:
        drop: [ALL]
  - name: log-aggregator
    image: images.my-company.example/log-aggregator:v6
    resources:
      requests:
        memory: "64Mi"
        cpu: "250m"
      limits:
        memory: "128Mi"
        cpu: "500m"
    securityContext:
      allowPrivilegeEscalation: false
      capabilities:
        drop: [ALL]

where:

spec.containers.resources.requests: Specifies that the container is requesting 64 Mi of memory and 250 m CPU.
spec.containers.resources.limits: Specifies the container’s limits are 128 Mi of memory and 500 m CPU.