Adding OWNERS for docs.
This commit is contained in:
foxish
@@ -1,5 +1,9 @@
|
||||
---
|
||||
---
|
||||
---
|
||||
assignees:
|
||||
- derekwaynecarr
|
||||
- janetkuo
|
||||
|
||||
---
|
||||
|
||||
By default, pods run with unbounded CPU and memory limits. This means that any pod in the
|
||||
system will be able to consume as much CPU and memory on the node that executes the pod.
|
||||
@@ -40,32 +44,32 @@ This example will work in a custom namespace to demonstrate the concepts involve
|
||||
|
||||
Let's create a new namespace called limit-example:
|
||||
|
||||
```shell
|
||||
$ kubectl create namespace limit-example
|
||||
namespace "limit-example" created
|
||||
```
|
||||
|
||||
Note that `kubectl` commands will print the type and name of the resource created or mutated, which can then be used in subsequent commands:
|
||||
|
||||
```shell
|
||||
```shell
|
||||
$ kubectl create namespace limit-example
|
||||
namespace "limit-example" created
|
||||
```
|
||||
|
||||
Note that `kubectl` commands will print the type and name of the resource created or mutated, which can then be used in subsequent commands:
|
||||
|
||||
```shell
|
||||
$ kubectl get namespaces
|
||||
NAME STATUS AGE
|
||||
default Active 51s
|
||||
limit-example Active 45s
|
||||
```
|
||||
|
||||
NAME STATUS AGE
|
||||
default Active 51s
|
||||
limit-example Active 45s
|
||||
```
|
||||
|
||||
## Step 2: Apply a limit to the namespace
|
||||
|
||||
Let's create a simple limit in our namespace.
|
||||
|
||||
```shell
|
||||
```shell
|
||||
$ kubectl create -f docs/admin/limitrange/limits.yaml --namespace=limit-example
|
||||
limitrange "mylimits" created
|
||||
```
|
||||
|
||||
```
|
||||
|
||||
Let's describe the limits that we have imposed in our namespace.
|
||||
|
||||
```shell
|
||||
```shell
|
||||
$ kubectl describe limits mylimits --namespace=limit-example
|
||||
Name: mylimits
|
||||
Namespace: limit-example
|
||||
@@ -75,8 +79,8 @@ Pod cpu 200m 2 - -
|
||||
Pod memory 6Mi 1Gi - - -
|
||||
Container cpu 100m 2 200m 300m -
|
||||
Container memory 3Mi 1Gi 100Mi 200Mi -
|
||||
```
|
||||
|
||||
```
|
||||
|
||||
In this scenario, we have said the following:
|
||||
|
||||
1. If a max constraint is specified for a resource (2 CPU and 1Gi memory in this case), then a limit
|
||||
@@ -103,108 +107,108 @@ of creation explaining why.
|
||||
Let's first spin up a [Deployment](/docs/user-guide/deployments) that creates a single container Pod to demonstrate
|
||||
how default values are applied to each pod.
|
||||
|
||||
```shell
|
||||
```shell
|
||||
$ kubectl run nginx --image=nginx --replicas=1 --namespace=limit-example
|
||||
deployment "nginx" created
|
||||
```
|
||||
|
||||
Note that `kubectl run` creates a Deployment named "nginx" on Kubernetes cluster >= v1.2. If you are running older versions, it creates replication controllers instead.
|
||||
If you want to obtain the old behavior, use `--generator=run/v1` to create replication controllers. See [`kubectl run`](/docs/user-guide/kubectl/kubectl_run/) for more details.
|
||||
The Deployment manages 1 replica of single container Pod. Let's take a look at the Pod it manages. First, find the name of the Pod:
|
||||
|
||||
```shell
|
||||
```
|
||||
|
||||
Note that `kubectl run` creates a Deployment named "nginx" on Kubernetes cluster >= v1.2. If you are running older versions, it creates replication controllers instead.
|
||||
If you want to obtain the old behavior, use `--generator=run/v1` to create replication controllers. See [`kubectl run`](/docs/user-guide/kubectl/kubectl_run/) for more details.
|
||||
The Deployment manages 1 replica of single container Pod. Let's take a look at the Pod it manages. First, find the name of the Pod:
|
||||
|
||||
```shell
|
||||
$ kubectl get pods --namespace=limit-example
|
||||
NAME READY STATUS RESTARTS AGE
|
||||
nginx-2040093540-s8vzu 1/1 Running 0 11s
|
||||
```
|
||||
|
||||
Let's print this Pod with yaml output format (using `-o yaml` flag), and then `grep` the `resources` field. Note that your pod name will be different.
|
||||
|
||||
``` shell
|
||||
NAME READY STATUS RESTARTS AGE
|
||||
nginx-2040093540-s8vzu 1/1 Running 0 11s
|
||||
```
|
||||
|
||||
Let's print this Pod with yaml output format (using `-o yaml` flag), and then `grep` the `resources` field. Note that your pod name will be different.
|
||||
|
||||
``` shell
|
||||
$ kubectl get pods nginx-2040093540-s8vzu --namespace=limit-example -o yaml | grep resources -C 8
|
||||
resourceVersion: "57"
|
||||
selfLink: /api/v1/namespaces/limit-example/pods/nginx-2040093540-ivimu
|
||||
uid: 67b20741-f53b-11e5-b066-64510658e388
|
||||
spec:
|
||||
containers:
|
||||
- image: nginx
|
||||
imagePullPolicy: Always
|
||||
name: nginx
|
||||
resources:
|
||||
limits:
|
||||
cpu: 300m
|
||||
memory: 200Mi
|
||||
requests:
|
||||
cpu: 200m
|
||||
memory: 100Mi
|
||||
terminationMessagePath: /dev/termination-log
|
||||
volumeMounts:
|
||||
```
|
||||
|
||||
resourceVersion: "57"
|
||||
selfLink: /api/v1/namespaces/limit-example/pods/nginx-2040093540-ivimu
|
||||
uid: 67b20741-f53b-11e5-b066-64510658e388
|
||||
spec:
|
||||
containers:
|
||||
- image: nginx
|
||||
imagePullPolicy: Always
|
||||
name: nginx
|
||||
resources:
|
||||
limits:
|
||||
cpu: 300m
|
||||
memory: 200Mi
|
||||
requests:
|
||||
cpu: 200m
|
||||
memory: 100Mi
|
||||
terminationMessagePath: /dev/termination-log
|
||||
volumeMounts:
|
||||
```
|
||||
|
||||
Note that our nginx container has picked up the namespace default cpu and memory resource *limits* and *requests*.
|
||||
|
||||
Let's create a pod that exceeds our allowed limits by having it have a container that requests 3 cpu cores.
|
||||
|
||||
```shell
|
||||
```shell
|
||||
$ kubectl create -f docs/admin/limitrange/invalid-pod.yaml --namespace=limit-example
|
||||
Error from server: error when creating "docs/admin/limitrange/invalid-pod.yaml": Pod "invalid-pod" is forbidden: [Maximum cpu usage per Pod is 2, but limit is 3., Maximum cpu usage per Container is 2, but limit is 3.]
|
||||
```
|
||||
|
||||
```
|
||||
|
||||
Let's create a pod that falls within the allowed limit boundaries.
|
||||
|
||||
```shell
|
||||
```shell
|
||||
$ kubectl create -f docs/admin/limitrange/valid-pod.yaml --namespace=limit-example
|
||||
pod "valid-pod" created
|
||||
```
|
||||
|
||||
Now look at the Pod's resources field:
|
||||
|
||||
```shell
|
||||
```
|
||||
|
||||
Now look at the Pod's resources field:
|
||||
|
||||
```shell
|
||||
$ kubectl get pods valid-pod --namespace=limit-example -o yaml | grep -C 6 resources
|
||||
uid: 3b1bfd7a-f53c-11e5-b066-64510658e388
|
||||
spec:
|
||||
containers:
|
||||
- image: gcr.io/google_containers/serve_hostname
|
||||
imagePullPolicy: Always
|
||||
name: kubernetes-serve-hostname
|
||||
resources:
|
||||
limits:
|
||||
cpu: "1"
|
||||
memory: 512Mi
|
||||
requests:
|
||||
cpu: "1"
|
||||
memory: 512Mi
|
||||
```
|
||||
|
||||
uid: 3b1bfd7a-f53c-11e5-b066-64510658e388
|
||||
spec:
|
||||
containers:
|
||||
- image: gcr.io/google_containers/serve_hostname
|
||||
imagePullPolicy: Always
|
||||
name: kubernetes-serve-hostname
|
||||
resources:
|
||||
limits:
|
||||
cpu: "1"
|
||||
memory: 512Mi
|
||||
requests:
|
||||
cpu: "1"
|
||||
memory: 512Mi
|
||||
```
|
||||
|
||||
Note that this pod specifies explicit resource *limits* and *requests* so it did not pick up the namespace
|
||||
default values.
|
||||
|
||||
Note: The *limits* for CPU resource are enforced in the default Kubernetes setup on the physical node
|
||||
that runs the container unless the administrator deploys the kubelet with the folllowing flag:
|
||||
|
||||
```shell
|
||||
```shell
|
||||
$ kubelet --help
|
||||
Usage of kubelet
|
||||
....
|
||||
--cpu-cfs-quota[=true]: Enable CPU CFS quota enforcement for containers that specify CPU limits
|
||||
$ kubelet --cpu-cfs-quota=false ...
|
||||
```
|
||||
|
||||
```
|
||||
|
||||
## Step 4: Cleanup
|
||||
|
||||
To remove the resources used by this example, you can just delete the limit-example namespace.
|
||||
|
||||
```shell
|
||||
```shell
|
||||
$ kubectl delete namespace limit-example
|
||||
namespace "limit-example" deleted
|
||||
$ kubectl get namespaces
|
||||
NAME STATUS AGE
|
||||
default Active 12m
|
||||
```
|
||||
|
||||
NAME STATUS AGE
|
||||
default Active 12m
|
||||
```
|
||||
|
||||
## Summary
|
||||
|
||||
Cluster operators that want to restrict the amount of resources a single container or pod may consume
|
||||
are able to define allowable ranges per Kubernetes namespace. In the absence of any explicit assignments,
|
||||
the Kubernetes system is able to apply default resource *limits* and *requests* if desired in order to
|
||||
constrain the amount of resource a pod consumes on a node.
|
||||
constrain the amount of resource a pod consumes on a node.
|
||||
|
||||
Reference in New Issue
Block a user