Example of NFS volume

See nfs-web-rc.yaml for a quick example of how to use an NFS volume claim in a replication controller. It relies on the NFS persistent volume and NFS persistent volume claim in this example as well.

Complete setup

The example below shows how to export a NFS share from a single pod replication controller and import it into two replication controllers.

NFS server part

Define NFS server controller and NFS service:

$ kubectl create -f examples/nfs/nfs-server-rc.yaml
$ kubectl create -f examples/nfs/nfs-server-service.yaml

The server exports /mnt/data directory as / (fsid=0). The directory contains dummy index.html. Wait until the pod is running by checking kubectl get pods -lrole=nfs-server.

Create the NFS claim

The NFS busybox controller uses a simple script to generate data written to the NFS server we just started. First, you'll need to find the cluster IP of the server:

$ kubectl describe services nfs-server

Replace the invalid IP in the nfs PV. (In the future, we'll be able to tie these together using the service names, but for now, you have to hardcode the IP.)

Create the the persistent volume and the persistent volume claim for your NFS server. The persistent volume and claim gives us an indirection that allow multiple pods to refer to the NFS server using a symbolic name rather than the hardcoded server address.

$ kubectl create -f examples/nfs/nfs-pv.yaml
$ kubectl create -f examples/nfs/nfs-pvc.yaml

Setup the fake backend

The NFS busybox controller updates index.html on the NFS server every 10 seconds. Let's start that now:

$ kubectl create -f examples/nfs/nfs-busybox-rc.yaml

Conveniently, it's also a busybox pod, so we can get an early check that our mounts are working now. Find a busybox pod and exec:

$ kubectl get pod -lname=nfs-busybox
NAME                READY     STATUS    RESTARTS   AGE
nfs-busybox-jdhf3   1/1       Running   0          25m
nfs-busybox-w3s4t   1/1       Running   0          25m
$ kubectl exec nfs-busybox-jdhf3 -- cat /mnt/index.html
Thu Oct 22 19:20:18 UTC 2015
nfs-busybox-w3s4t

You should see output similar to the above if everything is working well. If it's not, make sure you changed the invalid IP in the NFS PV file and make sure the describe services command above had endpoints listed (indicating the service was associated with a running pod).

Setup the web server

The web server controller is an another simple replication controller demonstrates reading from the NFS share exported above as a NFS volume and runs a simple web server on it.

Define the pod:

$ kubectl create -f examples/nfs/nfs-web-rc.yaml

This creates two pods, each of which serve the index.html from above. We can then use a simple service to front it:

kubectl create -f examples/nfs/nfs-web-service.yaml

We can then use the busybox container we launched before to check that nginx is serving the data appropriately:

$ kubectl get pod -lname=nfs-busybox
NAME                READY     STATUS    RESTARTS   AGE
nfs-busybox-jdhf3   1/1       Running   0          1h
nfs-busybox-w3s4t   1/1       Running   0          1h
$ kubectl get services nfs-web
NAME      LABELS    SELECTOR            IP(S)        PORT(S)
nfs-web   <none>    role=web-frontend   10.0.68.37   80/TCP
$ kubectl exec nfs-busybox-jdhf3 -- wget -qO- http://10.0.68.37
Thu Oct 22 19:28:55 UTC 2015
nfs-busybox-w3s4t