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205 lines
6.8 KiB
Markdown
205 lines
6.8 KiB
Markdown
<!-- BEGIN MUNGE: UNVERSIONED_WARNING -->
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<!-- BEGIN STRIP_FOR_RELEASE -->
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<img src="http://kubernetes.io/img/warning.png" alt="WARNING"
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width="25" height="25">
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<img src="http://kubernetes.io/img/warning.png" alt="WARNING"
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width="25" height="25">
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<img src="http://kubernetes.io/img/warning.png" alt="WARNING"
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width="25" height="25">
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<img src="http://kubernetes.io/img/warning.png" alt="WARNING"
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width="25" height="25">
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<img src="http://kubernetes.io/img/warning.png" alt="WARNING"
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width="25" height="25">
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<h2>PLEASE NOTE: This document applies to the HEAD of the source tree</h2>
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If you are using a released version of Kubernetes, you should
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refer to the docs that go with that version.
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<!-- TAG RELEASE_LINK, added by the munger automatically -->
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<strong>
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The latest release of this document can be found
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[here](http://releases.k8s.io/release-1.2/examples/nfs/README.md).
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Documentation for other releases can be found at
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[releases.k8s.io](http://releases.k8s.io).
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</strong>
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--
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<!-- END STRIP_FOR_RELEASE -->
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<!-- END MUNGE: UNVERSIONED_WARNING -->
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# Outline
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This example describes how to create Web frontend server, an auto-provisioned persistent volume on GCE, and an NFS-backed persistent claim.
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Demonstrated Kubernetes Concepts:
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* [Persistent Volumes](http://kubernetes.io/docs/user-guide/persistent-volumes/) to
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define persistent disks (disk lifecycle not tied to the Pods).
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* [Services](http://kubernetes.io/docs/user-guide/services/) to enable Pods to
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locate one another.
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![alt text][nfs pv example]
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As illustrated above, two persistent volumes are used in this example:
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- Web frontend Pod uses a persistent volume based on NFS server, and
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- NFS server uses an auto provisioned [persistent volume](http://kubernetes.io/docs/user-guide/persistent-volumes/) from GCE PD or AWS EBS.
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Note, this example uses an NFS container that doesn't support NFSv4.
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[nfs pv example]: nfs-pv.png
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## tl;dr Quickstart
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```console
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$ kubectl create -f examples/nfs/provisioner/nfs-server-gce-pv.yaml
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$ kubectl create -f examples/nfs/nfs-server-rc.yaml
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$ kubectl create -f examples/nfs/nfs-server-service.yaml
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# get the cluster IP of the server using the following command
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$ kubectl describe services nfs-server
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# use the NFS server IP to update nfs-pv.yaml and execute the following
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$ kubectl create -f examples/nfs/nfs-pv.yaml
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$ kubectl create -f examples/nfs/nfs-pvc.yaml
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# run a fake backend
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$ kubectl create -f examples/nfs/nfs-busybox-rc.yaml
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# get pod name from this command
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$ kubectl get pod -l name=nfs-busybox
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# use the pod name to check the test file
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$ kubectl exec nfs-busybox-jdhf3 -- cat /mnt/index.html
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```
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## Example of NFS based persistent volume
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See [NFS Service and Replication Controller](nfs-web-rc.yaml) for a quick example of how to use an NFS
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volume claim in a replication controller. It relies on the
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[NFS persistent volume](nfs-pv.yaml) and
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[NFS persistent volume claim](nfs-pvc.yaml) in this example as well.
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## Complete setup
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The example below shows how to export a NFS share from a single pod replication
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controller and import it into two replication controllers.
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### NFS server part
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Define [the NFS Service and Replication Controller](nfs-server-rc.yaml) and
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[NFS service](nfs-server-service.yaml):
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The NFS server exports an an auto-provisioned persistent volume backed by GCE PD:
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```console
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$ kubectl create -f examples/nfs/provisioner/nfs-server-gce-pv.yaml
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```
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```console
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$ kubectl create -f examples/nfs/nfs-server-rc.yaml
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$ kubectl create -f examples/nfs/nfs-server-service.yaml
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```
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The directory contains dummy `index.html`. Wait until the pod is running
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by checking `kubectl get pods -l role=nfs-server`.
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### Create the NFS based persistent volume claim
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The [NFS busybox controller](nfs-busybox-rc.yaml) uses a simple script to
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generate data written to the NFS server we just started. First, you'll need to
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find the cluster IP of the server:
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```console
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$ kubectl describe services nfs-server
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```
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Replace the invalid IP in the [nfs PV](nfs-pv.yaml). (In the future,
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we'll be able to tie these together using the service names, but for
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now, you have to hardcode the IP.)
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Create the the [persistent volume](../../docs/user-guide/persistent-volumes.md)
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and the persistent volume claim for your NFS server. The persistent volume and
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claim gives us an indirection that allow multiple pods to refer to the NFS
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server using a symbolic name rather than the hardcoded server address.
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```console
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$ kubectl create -f examples/nfs/nfs-pv.yaml
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$ kubectl create -f examples/nfs/nfs-pvc.yaml
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```
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## Setup the fake backend
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The [NFS busybox controller](nfs-busybox-rc.yaml) updates `index.html` on the
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NFS server every 10 seconds. Let's start that now:
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```console
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$ kubectl create -f examples/nfs/nfs-busybox-rc.yaml
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```
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Conveniently, it's also a `busybox` pod, so we can get an early check
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that our mounts are working now. Find a busybox pod and exec:
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```console
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$ kubectl get pod -l name=nfs-busybox
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NAME READY STATUS RESTARTS AGE
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nfs-busybox-jdhf3 1/1 Running 0 25m
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nfs-busybox-w3s4t 1/1 Running 0 25m
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$ kubectl exec nfs-busybox-jdhf3 -- cat /mnt/index.html
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Thu Oct 22 19:20:18 UTC 2015
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nfs-busybox-w3s4t
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```
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You should see output similar to the above if everything is working well. If
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it's not, make sure you changed the invalid IP in the [NFS PV](nfs-pv.yaml) file
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and make sure the `describe services` command above had endpoints listed
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(indicating the service was associated with a running pod).
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### Setup the web server
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The [web server controller](nfs-web-rc.yaml) is an another simple replication
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controller demonstrates reading from the NFS share exported above as a NFS
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volume and runs a simple web server on it.
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Define the pod:
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```console
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$ kubectl create -f examples/nfs/nfs-web-rc.yaml
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```
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This creates two pods, each of which serve the `index.html` from above. We can
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then use a simple service to front it:
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```console
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kubectl create -f examples/nfs/nfs-web-service.yaml
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```
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We can then use the busybox container we launched before to check that `nginx`
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is serving the data appropriately:
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```console
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$ kubectl get pod -l name=nfs-busybox
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NAME READY STATUS RESTARTS AGE
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nfs-busybox-jdhf3 1/1 Running 0 1h
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nfs-busybox-w3s4t 1/1 Running 0 1h
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$ kubectl get services nfs-web
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NAME LABELS SELECTOR IP(S) PORT(S)
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nfs-web <none> role=web-frontend 10.0.68.37 80/TCP
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$ kubectl exec nfs-busybox-jdhf3 -- wget -qO- http://10.0.68.37
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Thu Oct 22 19:28:55 UTC 2015
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nfs-busybox-w3s4t
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```
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<!-- BEGIN MUNGE: IS_VERSIONED -->
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<!-- TAG IS_VERSIONED -->
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<!-- END MUNGE: IS_VERSIONED -->
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<!-- BEGIN MUNGE: GENERATED_ANALYTICS -->
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[]()
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<!-- END MUNGE: GENERATED_ANALYTICS -->
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