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update resource-quota docs
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dinghaiyang
23
docs/admin/resource-quota.md
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23
docs/admin/resource-quota.md
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@@ -40,15 +40,24 @@ Resource quotas are a tool for administrators to address this concern. Resource
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work like this:
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- Different teams work in different namespaces. Currently this is voluntary, but
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support for making this mandatory via ACLs is planned.
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- Users put [compute resource limits](../user-guide/compute-resources.md) on their pods.
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- The administrator creates a Resource Quota for each namespace.
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- Users put compute resource requests on their pods. The sum of all resource requests across
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all pods in the same namespace must not exceed any hard resource limit in any Resource Quota
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document for the namespace. Note that we used to verify Resource Quota by taking the sum of
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resource limits of the pods, but this was altered to use resource requests. Backwards compatibility
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for those pods previously created is preserved because pods that only specify a resource limit have
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their resource requests defaulted to match their defined limits. The user is only charged for the
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resources they request in the Resource Quota versus their limits because the request is the minimum
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amount of resource guaranteed by the cluster during scheduling. For more information on over commit,
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see [compute-resources](../user-guide/compute-resources.md).
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- If creating a pod would cause the namespace to exceed any of the limits specified in the
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the Resource Quota for that namespace, then the request will fail with HTTP status
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code `403 FORBIDDEN`.
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- If quota is enabled in a namespace and the user does not specify limits on the pod for each
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- If quota is enabled in a namespace and the user does not specify *requests* on the pod for each
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of the resources for which quota is enabled, then the POST of the pod will fail with HTTP
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status code `403 FORBIDDEN`. Hint: Use the LimitRange admission controller to force default
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values of limits before the quota is checked to avoid this problem.
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values of *limits* (then resource *requests* would be equal to *limits* by default, see
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[admission controller](admission-controllers.md)) before the quota is checked to avoid this problem.
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Examples of policies that could be created using namespaces and quotas are:
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- In a cluster with a capacity of 32 GiB RAM, and 16 cores, let team A use 20 Gib and 10 cores,
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@@ -78,10 +87,10 @@ in a namespace can be limited. The following compute resource types are support
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| ResourceName | Description |
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| ------------ | ----------- |
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| cpu | Total cpu limits of containers |
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| memory | Total memory limits of containers
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| cpu | Total cpu requests of containers |
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| memory | Total memory requests of containers
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For example, `cpu` quota sums up the `resources.limits.cpu` fields of every
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For example, `cpu` quota sums up the `resources.requests.cpu` fields of every
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container of every pod in the namespace, and enforces a maximum on that sum.
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## Object Count Quota
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@@ -107,7 +116,7 @@ supply of Pod IPs.
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## Viewing and Setting Quotas
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Kubectl supports creating, updating, and viewing quotas
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Kubectl supports creating, updating, and viewing quotas:
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```console
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$ kubectl namespace myspace
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124
docs/admin/resourcequota/README.md
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124
docs/admin/resourcequota/README.md
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@@ -32,7 +32,9 @@ Documentation for other releases can be found at
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<!-- END MUNGE: UNVERSIONED_WARNING -->
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Resource Quota
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========================================
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This example demonstrates how [resource quota](../../admin/admission-controllers.md#resourcequota) and [limits](../../admin/admission-controllers.md#limitranger) can be applied to a Kubernetes namespace. See [ResourceQuota design doc](../../design/admission_control_resource_quota.md) for more information.
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This example demonstrates how [resource quota](../../admin/admission-controllers.md#resourcequota) and
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[limitsranger](../../admin/admission-controllers.md#limitranger) can be applied to a Kubernetes namespace.
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See [ResourceQuota design doc](../../design/admission_control_resource_quota.md) for more information.
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This example assumes you have a functional Kubernetes setup.
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@@ -44,26 +46,29 @@ Let's create a new namespace called quota-example:
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```console
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$ kubectl create -f docs/admin/resourcequota/namespace.yaml
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namespace "quota-example" created
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$ kubectl get namespaces
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NAME LABELS STATUS
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default <none> Active
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quota-example <none> Active
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NAME LABELS STATUS AGE
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default <none> Active 2m
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quota-example <none> Active 39s
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```
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Step 2: Apply a quota to the namespace
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-----------------------------------------
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By default, a pod will run with unbounded CPU and memory limits. This means that any pod in the
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By default, a pod will run with unbounded CPU and memory requests/limits. This means that any pod in the
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system will be able to consume as much CPU and memory on the node that executes the pod.
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Users may want to restrict how much of the cluster resources a given namespace may consume
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across all of its pods in order to manage cluster usage. To do this, a user applies a quota to
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a namespace. A quota lets the user set hard limits on the total amount of node resources (cpu, memory)
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and API resources (pods, services, etc.) that a namespace may consume.
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and API resources (pods, services, etc.) that a namespace may consume. In term of resources, Kubernetes
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checks the total resource *requests*, not resource *limits* of all containers/pods in the namespace.
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Let's create a simple quota in our namespace:
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```console
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$ kubectl create -f docs/admin/resourcequota/quota.yaml --namespace=quota-example
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resourcequota "quota" created
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```
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Once your quota is applied to a namespace, the system will restrict any creation of content
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@@ -74,23 +79,23 @@ namespace.
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```console
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$ kubectl describe quota quota --namespace=quota-example
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Name: quota
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Namespace: quota-example
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Resource Used Hard
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-------- ---- ----
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cpu 0 20
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memory 0 1Gi
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persistentvolumeclaims 0 10
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pods 0 10
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replicationcontrollers 0 20
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resourcequotas 1 1
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secrets 1 10
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services 0 5
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Name: quota
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Namespace: quota-example
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Resource Used Hard
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-------- ---- ----
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cpu 0 20
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memory 0 1Gi
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persistentvolumeclaims 0 10
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pods 0 10
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replicationcontrollers 0 20
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resourcequotas 1 1
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secrets 1 10
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services 0 5
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```
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Step 3: Applying default resource limits
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Step 3: Applying default resource requests and limits
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-----------------------------------------
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Pod authors rarely specify resource limits for their pods.
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Pod authors rarely specify resource requests and limits for their pods.
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Since we applied a quota to our project, let's see what happens when an end-user creates a pod that has unbounded
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cpu and memory by creating an nginx container.
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@@ -99,8 +104,7 @@ To demonstrate, lets create a replication controller that runs nginx:
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```console
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$ kubectl run nginx --image=nginx --replicas=1 --namespace=quota-example
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CONTROLLER CONTAINER(S) IMAGE(S) SELECTOR REPLICAS
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nginx nginx nginx run=nginx 1
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replicationcontroller "nginx" created
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```
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Now let's look at the pods that were created.
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@@ -114,78 +118,78 @@ What happened? I have no pods! Let's describe the replication controller to ge
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```console
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kubectl describe rc nginx --namespace=quota-example
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Name: nginx
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Image(s): nginx
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Selector: run=nginx
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Labels: run=nginx
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Replicas: 0 current / 1 desired
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Pods Status: 0 Running / 0 Waiting / 0 Succeeded / 0 Failed
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Name: nginx
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Namespace: quota-example
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Image(s): nginx
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Selector: run=nginx
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Labels: run=nginx
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Replicas: 0 current / 1 desired
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Pods Status: 0 Running / 0 Waiting / 0 Succeeded / 0 Failed
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No volumes.
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Events:
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FirstSeen LastSeen Count From SubobjectPath Reason Message
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Mon, 01 Jun 2015 22:49:31 -0400 Mon, 01 Jun 2015 22:52:22 -0400 7 {replication-controller } failedCreate Error creating: Pod "nginx-" is forbidden: Limited to 1Gi memory, but pod has no specified memory limit
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FirstSeen LastSeen Count From SubobjectPath Reason Message
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42s 11s 3 {replication-controller } FailedCreate Error creating: Pod "nginx-" is forbidden: Must make a non-zero request for memory since it is tracked by quota.
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```
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The Kubernetes API server is rejecting the replication controllers requests to create a pod because our pods
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do not specify any memory usage.
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do not specify any memory usage *request*.
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So let's set some default limits for the amount of cpu and memory a pod can consume:
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So let's set some default values for the amount of cpu and memory a pod can consume:
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```console
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$ kubectl create -f docs/admin/resourcequota/limits.yaml --namespace=quota-example
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limitranges/limits
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limitrange "limits" created
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$ kubectl describe limits limits --namespace=quota-example
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Name: limits
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Namespace: quota-example
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Type Resource Min Max Default
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---- -------- --- --- ---
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Container memory - - 512Mi
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Container cpu - - 100m
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Name: limits
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Namespace: quota-example
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Type Resource Min Max Request Limit Limit/Request
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---- -------- --- --- ------- ----- -------------
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Container memory - - 256Mi 512Mi -
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Container cpu - - 100m 200m -
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```
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Now any time a pod is created in this namespace, if it has not specified any resource limits, the default
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amount of cpu and memory per container will be applied as part of admission control.
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Now any time a pod is created in this namespace, if it has not specified any resource request/limit, the default
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amount of cpu and memory per container will be applied, and the request will be used as part of admission control.
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Now that we have applied default limits for our namespace, our replication controller should be able to
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Now that we have applied default resource *request* for our namespace, our replication controller should be able to
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create its pods.
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```console
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$ kubectl get pods --namespace=quota-example
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NAME READY STATUS RESTARTS AGE
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nginx-t9cap 1/1 Running 0 49s
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nginx-fca65 1/1 Running 0 1m
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```
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And if we print out our quota usage in the namespace:
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```console
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$ kubectl describe quota quota --namespace=quota-example
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Name: quota
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Namespace: default
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Resource Used Hard
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-------- ---- ----
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cpu 100m 20
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memory 536870912 1Gi
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persistentvolumeclaims 0 10
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pods 1 10
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replicationcontrollers 1 20
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resourcequotas 1 1
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secrets 1 10
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services 0 5
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Name: quota
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Namespace: quota-example
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Resource Used Hard
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-------- ---- ----
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cpu 100m 20
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memory 256Mi 1Gi
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persistentvolumeclaims 0 10
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pods 1 10
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replicationcontrollers 1 20
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resourcequotas 1 1
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secrets 1 10
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services 0 5
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```
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You can now see the pod that was created is consuming explicit amounts of resources, and the usage is being
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tracked by the Kubernetes system properly.
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You can now see the pod that was created is consuming explicit amounts of resources (specified by resource *request*),
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and the usage is being tracked by the Kubernetes system properly.
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Summary
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----------------------------
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Actions that consume node resources for cpu and memory can be subject to hard quota limits defined
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by the namespace quota.
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by the namespace quota. The resource consumption is measured by resource *request* in pod specification.
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Any action that consumes those resources can be tweaked, or can pick up namespace level defaults to
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meet your end goal.
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<!-- BEGIN MUNGE: GENERATED_ANALYTICS -->
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[]()
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<!-- END MUNGE: GENERATED_ANALYTICS -->
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5
docs/admin/resourcequota/limits.yaml
Normal file → Executable file
5
docs/admin/resourcequota/limits.yaml
Normal file → Executable file
@@ -5,6 +5,9 @@ metadata:
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spec:
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limits:
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- default:
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cpu: 100m
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cpu: 200m
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memory: 512Mi
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defaultRequest:
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cpu: 100m
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memory: 256Mi
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type: Container
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