17fd5f2536
This ensures nfs-common is installed on GCE, and provides a more functional explanation/example. I launched two replication controllers so that there were busybox pods to poke around at the NFS volume, and so that the later wget actually works (the original example would have to work on the node, or need some other access to the container network). After switching to two controllers, it actually makes more sense to use PV claims, and it's probably a configuration that makes more sense for indirection for NFS anyways.
150 lines
4.9 KiB
Markdown
150 lines
4.9 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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<strong>
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The latest 1.0.x release of this document can be found
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[here](http://releases.k8s.io/release-1.0/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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# Example of NFS volume
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See [nfs-web-rc.yaml](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 [NFS server controller](nfs-server-rc.yaml) and
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[NFS service](nfs-server-service.yaml):
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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 server exports `/mnt/data` directory as `/` (fsid=0). The
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directory contains dummy `index.html`. Wait until the pod is running
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by checking `kubectl get pods -lrole=nfs-server`.
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### Create the NFS 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 -lname=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 -lname=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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