kubernetes-management-setting-resource-requests-and-limits

Setting Resource Requests and Limits

Resource requests and limits in Kubernetes specify the minimum and maximum amount of CPU and memory a container requires to run. Resource requests are used for scheduling containers on nodes with sufficient resources, while limits enforce resource quotas and prevent containers from consuming too much. These settings can be configured at the pod or container level using the resources field in YAML. It’s important to set resource requests and limits correctly to ensure optimal resource utilization in your Kubernetes cluster.

Learn more from the following resources:

Managing Requests and Limits

Cluster resources like CPU and memory change as rolling updates occur. To control these resources:

requests: determine the minimum amount of CPU and memory that a container will be allocated on a node.
limits: set the upper boundary of how much CPU and memory a container can use on a node.

Requests cannot be lower than limits, and both must be specified for each individual container in the Pod. Pods are scheduled as a group, so you still need to calculate the total resource requests and limits by adding up the values from each individual container within the Pod.

Kube-Scheduler

Kubernetes uses the Kube-scheduler to decide which node to place the Pod on. If the optimal node cannot be found for the request, it is sent back to the Kube-scheduler to try again. Once the optimal node is found, the kubelet is used to enforce resource limits and ensure that the running container is not allowed to use more of that resource than the limit set.

Kube-Let

The kubelet is also responsible for reserving request amounts for containers.

CPU Resources

CPU resources are measured in millicores. A container that needs two full cores to run would be measured as 2,000m, millicores. A container that needs one quarter of a core would be measured as 250m.

flowchart TD
    A[Incoming Requests & Limits] --> B[Kube-scheduler]
    B --> C{Optimal Node?}
    C -- No --> B
    C -- Yes --> D[Kubelet]
    D --> E[Node]
    E --> F[Resource Limits Enforced]
    
    F ---|Enforces resource limits| F
    F ---|Ensures containers don't exceed limits| F
    F ---|Reserves request amounts for containers| F

Flashcard

Requests:: Requests determine the minimum amount of CPU and memory that a container will be allocated on a node

Limits::Limits can set the upper boundary of how much CPU and memory a container can use on a node

kubernetes-management-setting-resource-requests-and-limits

Contents

Setting Resource Requests and Limits

Flashcard