Update Task topics on resource management. (#4158)

2017-08-07 15:30:29 -07:00
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+---
+title: Configure Minimum and Maximum Memory Constraints for a Namespace
+---
+
+
+{% capture overview %}
+
+This page shows how to set minimum and maximum values for memory used by Containers
+running in a namespace. You specify minimum and maximum memory values in a
+[LimitRange](/docs/api-reference/v1.6/#limitrange-v1-core)
+object. If a Pod does not meet the constraints imposed by the LimitRange,
+it cannot be created in the namespace.
+
+{% endcapture %}
+
+
+{% capture prerequisites %}
+
+{% include task-tutorial-prereqs.md %}
+
+Each node in your cluster must have at least 1 GiB of memory.
+
+{% endcapture %}
+
+
+{% 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-mem-example
+```
+
+## Create a LimitRange and a Pod
+
+Here's the configuration file for a LimitRange:
+
+{% include code.html language="yaml" file="memory-constraints.yaml" ghlink="/docs/tasks/administer-cluster/memory-constraints.yaml" %}
+
+Create the LimitRange:
+
+```shell
+kubectl create -f https://k8s.io/docs/tasks/administer-cluster/memory-constraints.yaml --namespace=constraints-mem-example
+```
+
+View detailed information about the LimitRange:
+
+```shell
+kubectl get limitrange cpu-min-max-demo --namespace=constraints-mem-example --output=yaml
+```
+
+The output shows the minimum and maximum memory 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.
+
+```
+  limits:
+  - default:
+      memory: 1Gi
+    defaultRequest:
+      memory: 1Gi
+    max:
+      memory: 1Gi
+    min:
+      memory: 500Mi
+    type: Container
+```
+
+Now whenever a Container is created in the constraints-mem-example namespace, Kubernetes
+performs these steps:
+
+* If the Container does not specify its own memory request and limit, assign the default
+memory request and limit to the Container.
+
+* Verify that the Container has a memory request that is greater than or equal to 500 MiB.
+
+* Verify that the Container has a memory limit that is less than or equal to 1 GiB.
+
+Here's the configuration file for a Pod that has one Container. The Container manifest
+specifies a memory request of 600 MiB and a memory limit of 800 MiB. These satisfy the
+minimum and maximum memory constraints imposed by the LimitRange.
+
+{% include code.html language="yaml" file="memory-constraints-pod.yaml" ghlink="/docs/tasks/administer-cluster/memory-constraints-pod.yaml" %}
+
+Create the Pod:
+
+```shell
+kubectl create -f https://k8s.io/docs/tasks/administer-cluster/memory-constraints-pod.yaml --namespace=constraints-mem-example
+```
+
+Verify that the Pod's Container is running:
+
+```shell
+kubectl get pod constraints-mem-demo --namespace=constraints-mem-example
+```
+
+View detailed information about the Pod:
+
+```shell
+kubectl get pod constraints-mem-demo --output=yaml --namespace=constraints-mem-example
+```
+
+The output shows that the Container has a memory request of 600 MiB and a memory limit
+of 800 MiB. These satisfy the constraints imposed by the LimitRange.
+
+```yaml
+resources:
+  limits:
+     memory: 800Mi
+  requests:
+    memory: 600Mi
+```
+
+Delete your Pod:
+
+```shell
+kubectl delete pod constraints-mem-demo --namespace=constraints-mem-example
+```
+
+## Attempt to create a Pod that exceeds the maximum memory constraint
+
+Here's the configuration file for a Pod that has one Container. The Container specifies a
+memory request of 700 MiB and a memory limit of 1.5 GiB.
+
+{% include code.html language="yaml" file="memory-constraints-pod-2.yaml" ghlink="/docs/tasks/administer-cluster/memory-constraints-pod-2.yaml" %}
+
+Attempt to create the Pod:
+
+```shell
+kubectl create -f https://k8s.io/docs/tasks/administer-cluster/memory-constraints-pod-2.yaml --namespace=constraints-mem-example
+```
+
+The output shows that the Pod does not get created, because the Container specifies a memory limit that is
+too large:
+
+```
+Error from server (Forbidden): error when creating "docs/tasks/administer-cluster/memory-constraints-pod-2.yaml":
+pods "constraints-mem-demo-2" is forbidden: maximum memory usage per Container is 1Gi, but limit is 1536Mi.
+```
+
+## Attempt to create a Pod that does not meet the minimum memory request
+
+Here's the configuration file for a Pod that has one Container. The Container specifies a
+memory request of 200 MiB and a memory limit of 800 MiB.
+
+{% include code.html language="yaml" file="memory-constraints-pod-3.yaml" ghlink="/docs/tasks/administer-cluster/memory-constraints-pod-3.yaml" %}
+
+Attempt to create the Pod:
+
+```shell
+kubectl create -f https://k8s.io/docs/tasks/administer-cluster/memory-constraints-pod-3.yaml --namespace=constraints-mem-example
+```
+
+The output shows that the Pod does not get created, because the Container specifies a memory
+request that is too small:
+
+```
+Error from server (Forbidden): error when creating "docs/tasks/administer-cluster/memory-constraints-pod-3.yaml":
+pods "constraints-mem-demo-3" is forbidden: minimum memory usage per Container is 500Mi, but request is 100Mi.
+```
+
+## 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 memory request, and it does not specify a memory limit.
+
+{% include code.html language="yaml" file="memory-constraints-pod-4.yaml" ghlink="/docs/tasks/administer-cluster/memory-constraints-pod-4.yaml" %}
+
+Create the Pod:
+
+```shell
+kubectl create -f https://k8s.io/docs/tasks/administer-cluster/memory-constraints-pod-4.yaml --namespace=constraints-mem-example
+```
+
+View detailed information about the Pod:
+
+```
+kubectl get pod constraints-mem-demo-4 --namespace=constraints-mem-example --output=yaml
+```
+
+The output shows that the Pod's Container has a memory request of 1 GiB and a memory limit of 1 GiB.
+How did the Container get those values?
+
+```
+resources:
+  limits:
+    memory: 1Gi
+  requests:
+    memory: 1Gi
+```
+
+Because your Container did not specify its own memory request and limit, it was given the
+[default memory request and limit](/docs/tasks/administer-cluster/default-memory-request-limit/)
+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 GiB of memory. If each of your Nodes has only
+1 GiB of memory, then there is not enough allocatable memory on any Node to accommodate a memory
+request of 1 GiB. If you happen to be using Nodes with 2 GiB of memory, then you probably have
+enough space to accommodate the 1 GiB request.
+
+Delete your Pod:
+
+```
+kubectl delete pod constraints-mem-demo-4 --namespace=constraints-mem-example
+```
+
+## Enforcement of minimum and maximum memory constraints
+
+The maximum and minimum memory 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 memory constraints
+
+As a cluster administrator, you might want to impose restrictions on the amount of memory that Pods can use.
+For example:
+
+* Each Node in a cluster has 2 GB of memory. You do not want to accept any Pod that requests
+more than 2 GB of memory, 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 8 GB of memory, but
+you want development workloads to be limited to 512 MB. You create separate namespaces
+for production and development, and you apply memory constraints to each namespace.
+
+## Clean up
+
+Delete your namespace:
+
+```shell
+kubectl delete namespace constraints-mem-example
+```
+
+{% endcapture %}
+
+{% capture whatsnext %}
+
+### For cluster administrators
+
+* [Configure Default Memory Requests and Limits for a Namespace](docs/tasks/administer-cluster/default-memory-request-limit/)
+
+* [Configure Default CPU Requests and Limits for a Namespace](docs/tasks/administer-cluster/default-cpu-request-limit/)
+
+* [Configure Minimum and Maximum CPU Constraints for a Namespace](/docs/tasks/administer-cluster/cpu-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/)
+
+{% endcapture %}
+
+
+{% include templates/task.md %}
+
+