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12-Resource-Limits.md

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Resource Limits

In this section we will take a look at Resource Limits

Let us take a look at 3 node kubernetes cluster.

  • Each node has a set of CPU, Memory and Disk resources available.

  • If there is no sufficient resources available on any of the nodes, kubernetes holds the scheduling the pod. You will see the pod in pending state. If you look at the events, you will see the reason as insufficient CPU.

    rl

Resource Requirements

  • By default, K8s assume that a pod or container within a pod requires 0.5 CPU and 256Mi of memory. This is known as the Resource Request for a container.

    rr

  • If your application within the pod requires more than the default resources, you need to set them in the pod definition file.

    apiVersion: v1
    kind: Pod
    metadata:
      name: simple-webapp-color
      labels:
        name: simple-webapp-color
    spec:
     containers:
     - name: simple-webapp-color
       image: simple-webapp-color
       ports:
        - containerPort:  8080
       resources:
         requests:
          memory: "1Gi"
          cpu: "1"
    

    rr-pod

Resources - Limits

  • By default, k8s sets resource limits to 1 CPU and 512Mi of memory

    rsl

  • You can set the resource limits in the pod definition file.

    apiVersion: v1
    kind: Pod
    metadata:
      name: simple-webapp-color
      labels:
        name: simple-webapp-color
    spec:
     containers:
     - name: simple-webapp-color
       image: simple-webapp-color
       ports:
        - containerPort:  8080
       resources:
         requests:
          memory: "1Gi"
          cpu: "1"
         limits:
           memory: "2Gi"
           cpu: "2"
    

    rsl1

Note: Remember Requests and Limits for resources are set per container in the pod.

Exceed Limits

  • what happens when a pod tries to exceed resources beyond its limits?

    el

K8s Reference Docs: