website/content/en/docs/tasks/administer-cluster/manage-resources/cpu-constraint-namespace.md

---
title: Configure Minimum and Maximum CPU Constraints for a Namespace
content_template: templates/task
weight: 40
---


{{% capture overview %}}

This page shows how to set minimum and maximum values for the CPU resources used by Containers
and Pods in a namespace. You specify minimum and maximum CPU values in a
[LimitRange](/docs/reference/generated/kubernetes-api/{{< param "version" >}}/#limitrange-v1-core)
object. If a Pod does not meet the constraints imposed by the LimitRange, it cannot be created
in the namespace.

{{% /capture %}}


{{% capture prerequisites %}}

{{< include "task-tutorial-prereqs.md" >}} {{< version-check >}}

Each node in your cluster must have at least 1 CPU.

{{% /capture %}}


{{% capture steps %}}

## Create a namespace

Create a namespace so that the resources you create in this exercise are
isolated from the rest of your cluster.

```shell
kubectl create namespace constraints-cpu-example
```

## Create a LimitRange and a Pod

Here's the configuration file for a LimitRange:

{{< codenew file="admin/resource/cpu-constraints.yaml" >}}

Create the LimitRange:

```shell
kubectl apply -f https://k8s.io/examples/admin/resource/cpu-constraints.yaml --namespace=constraints-cpu-example
```

View detailed information about the LimitRange:

```shell
kubectl get limitrange cpu-min-max-demo-lr --output=yaml --namespace=constraints-cpu-example
```

The output shows the minimum and maximum CPU constraints as expected. But
notice that even though you didn't specify default values in the configuration
file for the LimitRange, they were created automatically.

```yaml
limits:
- default:
    cpu: 800m
  defaultRequest:
    cpu: 800m
  max:
    cpu: 800m
  min:
    cpu: 200m
  type: Container
```

Now whenever a Container is created in the constraints-cpu-example namespace, Kubernetes
performs these steps:

* If the Container does not specify its own CPU request and limit, assign the default
CPU request and limit to the Container.

* Verify that the Container specifies a CPU request that is greater than or equal to 200 millicpu.

* Verify that the Container specifies a CPU limit that is less than or equal to 800 millicpu.

{{< note >}}
When creating a `LimitRange` object, you can specify limits on huge-pages
or GPUs as well. However, when both `default` and `defaultRequest` are specified
on these resources, the two values must be the same.
{{< /note >}}

Here's the configuration file for a Pod that has one Container. The Container manifest
specifies a CPU request of 500 millicpu and a CPU limit of 800 millicpu. These satisfy the
minimum and maximum CPU constraints imposed by the LimitRange.

{{< codenew file="admin/resource/cpu-constraints-pod.yaml" >}}

Create the Pod:

```shell
kubectl apply -f https://k8s.io/examples/admin/resource/cpu-constraints-pod.yaml --namespace=constraints-cpu-example
```

Verify that the Pod's Container is running:

```shell
kubectl get pod constraints-cpu-demo --namespace=constraints-cpu-example
```

View detailed information about the Pod:

```shell
kubectl get pod constraints-cpu-demo --output=yaml --namespace=constraints-cpu-example
```

The output shows that the Container has a CPU request of 500 millicpu and CPU limit
of 800 millicpu. These satisfy the constraints imposed by the LimitRange.

```yaml
resources:
  limits:
    cpu: 800m
  requests:
    cpu: 500m
```

## Delete the Pod

```shell
kubectl delete pod constraints-cpu-demo --namespace=constraints-cpu-example
```

## Attempt to create a Pod that exceeds the maximum CPU constraint

Here's the configuration file for a Pod that has one Container. The Container specifies a
CPU request of 500 millicpu and a cpu limit of 1.5 cpu.

{{< codenew file="admin/resource/cpu-constraints-pod-2.yaml" >}}

Attempt to create the Pod:

```shell
kubectl apply -f https://k8s.io/examples/admin/resource/cpu-constraints-pod-2.yaml --namespace=constraints-cpu-example
```

The output shows that the Pod does not get created, because the Container specifies a CPU limit that is
too large:

```
Error from server (Forbidden): error when creating "examples/admin/resource/cpu-constraints-pod-2.yaml":
pods "constraints-cpu-demo-2" is forbidden: maximum cpu usage per Container is 800m, but limit is 1500m.
```

## Attempt to create a Pod that does not meet the minimum CPU request

Here's the configuration file for a Pod that has one Container. The Container specifies a
CPU request of 100 millicpu and a CPU limit of 800 millicpu.

{{< codenew file="admin/resource/cpu-constraints-pod-3.yaml" >}}

Attempt to create the Pod:

```shell
kubectl apply -f https://k8s.io/examples/admin/resource/cpu-constraints-pod-3.yaml --namespace=constraints-cpu-example
```

The output shows that the Pod does not get created, because the Container specifies a CPU
request that is too small:

```
Error from server (Forbidden): error when creating "examples/admin/resource/cpu-constraints-pod-3.yaml":
pods "constraints-cpu-demo-3" is forbidden: minimum cpu usage per Container is 200m, but request is 100m.
```

## Create a Pod that does not specify any CPU request or limit

Here's the configuration file for a Pod that has one Container. The Container does not
specify a CPU request, and it does not specify a CPU limit.

{{< codenew file="admin/resource/cpu-constraints-pod-4.yaml" >}}

Create the Pod:

```shell
kubectl apply -f https://k8s.io/examples/admin/resource/cpu-constraints-pod-4.yaml --namespace=constraints-cpu-example
```

View detailed information about the Pod:

```
kubectl get pod constraints-cpu-demo-4 --namespace=constraints-cpu-example --output=yaml
```

The output shows that the Pod's Container has a CPU request of 800 millicpu and a CPU limit of 800 millicpu.
How did the Container get those values?

```yaml
resources:
  limits:
    cpu: 800m
  requests:
    cpu: 800m
```

Because your Container did not specify its own CPU request and limit, it was given the
[default CPU request and limit](/docs/tasks/administer-cluster/cpu-default-namespace/)
from the LimitRange.

At this point, your Container might be running or it might not be running. Recall that a prerequisite
for this task is that your Nodes have at least 1 CPU. If each of your Nodes has only
1 CPU, then there might not be enough allocatable CPU on any Node to accommodate a request
of 800 millicpu. If you happen to be using Nodes with 2 CPU, then you probably have
enough CPU to accommodate the 800 millicpu request.

Delete your Pod:

```
kubectl delete pod constraints-cpu-demo-4 --namespace=constraints-cpu-example
```

## Enforcement of minimum and maximum CPU constraints

The maximum and minimum CPU constraints imposed on a namespace by a LimitRange are enforced only
when a Pod is created or updated. If you change the LimitRange, it does not affect
Pods that were created previously.

## Motivation for minimum and maximum CPU constraints

As a cluster administrator, you might want to impose restrictions on the CPU resources that Pods can use.
For example:

* Each Node in a cluster has 2 CPU. You do not want to accept any Pod that requests
more than 2 CPU, because no Node in the cluster can support the request.

* A cluster is shared by your production and development departments.
You want to allow production workloads to consume up to 3 CPU, but you want development workloads to be limited
to 1 CPU. You create separate namespaces for production and development, and you apply CPU constraints to
each namespace.

## Clean up

Delete your namespace:

```shell
kubectl delete namespace constraints-cpu-example
```

{{% /capture %}}

{{% capture whatsnext %}}

### For cluster administrators

* [Configure Default Memory Requests and Limits for a Namespace](/docs/tasks/administer-cluster/memory-default-namespace/)

* [Configure Default CPU Requests and Limits for a Namespace](/docs/tasks/administer-cluster/cpu-default-namespace/)

* [Configure Minimum and Maximum Memory Constraints for a Namespace](/docs/tasks/administer-cluster/memory-constraint-namespace/)

* [Configure Memory and CPU Quotas for a Namespace](/docs/tasks/administer-cluster/quota-memory-cpu-namespace/)

* [Configure a Pod Quota for a Namespace](/docs/tasks/administer-cluster/quota-pod-namespace/)

* [Configure Quotas for API Objects](/docs/tasks/administer-cluster/quota-api-object/)

### For app developers

* [Assign Memory Resources to Containers and Pods](/docs/tasks/configure-pod-container/assign-memory-resource/)

* [Assign CPU Resources to Containers and Pods](/docs/tasks/configure-pod-container/assign-cpu-resource/)

* [Configure Quality of Service for Pods](/docs/tasks/configure-pod-container/quality-service-pod/)


{{% /capture %}}