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Further update docs to reflect changes kubectl run

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This commit is contained in:
Janet Kuo
2016-03-28 18:08:58 -07:00
parent 8f8a777ae2
commit abdcfbea30
8 changed files with 393 additions and 328 deletions
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docs/admin/limitrange/index.md
+62 -46
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@@ -22,7 +22,7 @@ may be too small to be useful, but big enough for the waste to be costly over th
the cluster operator may want to set limits that a pod must consume at least 20% of the memory and cpu of their
average node size in order to provide for more uniform scheduling and to limit waste.
This example demonstrates how limits can be applied to a Kubernetes namespace to control
This example demonstrates how limits can be applied to a Kubernetes [namespace](/docs/admin/namespaces) to control
min/max resource limits per pod. In addition, this example demonstrates how you can
apply default resource limits to pods in the absence of an end-user specified value.
@@ -41,12 +41,17 @@ 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 -f docs/admin/limitrange/namespace.yaml
namespace "limit-example" created
$ 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 LABELS STATUS AGE
default <none> Active 5m
limit-example <none> Active 53s
NAME STATUS AGE
default Active 51s
limit-example Active 45s
```
## Step 2: Apply a limit to the namespace
@@ -95,36 +100,45 @@ were previously created in a namespace.
If a resource (cpu or memory) is being restricted by a limit, the user will get an error at time
of creation explaining why.
Let's first spin up a deployment that creates a single container pod to demonstrate
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
$ 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
$ kubectl get pods --namespace=limit-example
NAME READY STATUS RESTARTS AGE
nginx-2040093540-s8vzu 1/1 Running 0 11s
$ kubectl get pods nginx-2040093540-s8vzu --namespace=limit-example -o yaml | grep resources -C 8
```
```yaml
resourceVersion: "127"
selfLink: /api/v1/namespaces/limit-example/pods/nginx-aq0mf
uid: 51be42a7-7156-11e5-9921-286ed488f785
spec:
containers:
- image: nginx
imagePullPolicy: IfNotPresent
name: nginx
resources:
limits:
cpu: 300m
memory: 200Mi
requests:
cpu: 200m
memory: 100Mi
terminationMessagePath: /dev/termination-log
volumeMounts:
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:
```
Note that our nginx container has picked up the namespace default cpu and memory resource *limits* and *requests*.
@@ -141,37 +155,39 @@ Let's create a pod that falls within the allowed limit boundaries.
```shell
$ kubectl create -f docs/admin/limitrange/valid-pod.yaml --namespace=limit-example
pod "valid-pod" created
$ kubectl get pods valid-pod --namespace=limit-example -o yaml | grep -C 6 resources
```
```yaml
uid: 162a12aa-7157-11e5-9921-286ed488f785
spec:
containers:
- image: gcr.io/google_containers/serve_hostname
imagePullPolicy: IfNotPresent
name: kubernetes-serve-hostname
resources:
limits:
cpu: "1"
memory: 512Mi
requests:
cpu: "1"
memory: 512Mi
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
```
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 not enforced in the default Kubernetes setup on the physical node
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
$ kubelet --help
Usage of kubelet
....
--cpu-cfs-quota[=false]: Enable CPU CFS quota enforcement for containers that specify CPU limits
$ kubelet --cpu-cfs-quota=true ...
--cpu-cfs-quota[=true]: Enable CPU CFS quota enforcement for containers that specify CPU limits
$ kubelet --cpu-cfs-quota=false ...
```
## Step 4: Cleanup
@@ -182,8 +198,8 @@ To remove the resources used by this example, you can just delete the limit-exam
$ kubectl delete namespace limit-example
namespace "limit-example" deleted
$ kubectl get namespaces
NAME LABELS STATUS AGE
default <none> Active 20m
NAME STATUS AGE
default Active 12m
```
## Summary