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Table of Contents generated with DocToc

A Simple PHP Example

Let's take some time to build a simple PHP example. Using PHP will make it easy for us to demonstrate persistent storage.

Create a PHP Project

As alice, create a project called php-upload.

Build the App

The source code for the application is here:

https://github.com/thoraxe/openshift-php-upload-demo

Using the skills you've learned so far, get this code running in your new project. Remember that you'll have to select the PHP builder (if you use the WebUI). Call this new application/service "demo".

Create a Route

Using the skills you've learned so far, use the expose subcommand to create a route for your app. If you used the WebUI, make sure you created a default route.

Visit the Application

Once your code is built, visit your application. Your URL probably looks something like:

http://demo-php-upload.cloudapps.example.com/

There should be a file picker and an upload button. Try to upload something and see what happens.

Error!

You are not allowed to upload a file. This is because the area of the Docker image where the applicaion content lives (/opt/app-root/src/) is not writeable by the user that is running the PHP process.

As alice in a terminal, make sure you are using the php-upload project (that's what you called it, right?) and then find the name of your demo pod. Then, do the following:

oc exec demo-1-kly7h -- sh -c 'whoami; ls -al'
whoami: cannot find name for user ID 1000100000
total 24
drwxr-xr-x. 3 default default 4096 Sep 15 14:36 .
drwxr-xr-x. 4 default default 4096 Sep  8 12:41 ..
-rw-r--r--. 1 default default  365 Sep 15 14:36 index.html
-rw-r--r--. 1 default default   20 Sep 15 14:36 info.php
-rw-r--r--. 1 default default  700 Sep 15 14:36 upload.php
drwxr-xr-x. 2 default default 4096 Sep 15 14:36 uploaded

You can see that the user you are (1000100000) is not who owns the uploaded folder (default). And the uploaded folder does not have world-writeable permissions.

But, that's OK, because we're going to add storage to our application containers.

Export Another NFS Volume

Earlier in the labs you created an NFS export to store your Docker registry data. We're going to add another one for use with this PHP application. On your master and as root:

  1. Create the directory we will export:

     mkdir -p /var/export/vol1
 chown nobody:nobody /var/export/vol1
 chmod 777 /var/export/vol1

  2. Edit /etc/exports and add the following line:

     /var/export/vol1 *(rw,sync,all_squash)

  3. Execute exportfs -r to tell NFS to refresh its exports.

You can validate that your new export is there with the following:

showmount -e
Export list for ose3-master.example.com:
/var/export/vol1   *
/var/export/regvol *

Create a PersistentVolume

Much like with the registry, it's up to an administrator to create a PersistentVolume. The following JSON definition can be found in content/php-volume.json:

{
  "apiVersion": "v1",
  "kind": "PersistentVolume",
  "metadata": {
    "name": "php-volume"
  },
  "spec": {
    "capacity": {
        "storage": "3Gi"
        },
    "accessModes": [ "ReadWriteMany" ],
    "nfs": {
        "path": "/var/export/vol1",
        "server": "ose3-master.example.com"
    }
  }
}

As the root user, go ahead and create this volume:

oc create -f ~/training/content/php-volume.json

Create a PersistentVolumeClaim

Once the volume is created, a project needs to claim it, much like with the registry. There is a claim in content/php-claim.json that looks like:

{
  "apiVersion": "v1",
  "kind": "PersistentVolumeClaim",
  "metadata": {
    "name": "php-claim"
  },
  "spec": {
    "accessModes": [ "ReadWriteMany" ],
    "resources": {
      "requests": {
        "storage": "3Gi"
      }
    }
  }
}

As alice and in the php-upload project, go ahead and create this claim:

oc create -f ~/training/content/php-claim.json

If you accidentally do this as root or in the wrong project, you might see a strange error in the pod when it comes up about the volume. Make sure you create this claim in the php-upload project. Claims and volumes can be deleted and recreated just like other objects. So, if you create the claim in the wrong place, just delete it and recreate it.

Add the Volume to Your DeploymentConfig

Much like we did with the registry, it's pretty easy for a user to tell OpenShift how to use a storage volume with an application. Our friend the oc volume command comes back to our rescue. As alice you can do the following:

oc volume dc/demo --add -t pvc --claim-name php-claim \
-m /opt/app-root/src/uploaded --name=php-volume

This command tells OpenShift:

  • modify the DeploymentConfig to add a volume
  • use the persistent volume claim called php-claim
  • give the volume the name php-volume
  • and mount it at /opt/app-root/src/uploaded

When you make this change, you will see that OpenShift will increment the version of the deployment configuration:

oc get dc
NAME      TRIGGERS                    LATEST VERSION
demo      ConfigChange, ImageChange   2

And we will get a new replication controller that has a pod template with the new volume information. Ultimately, we'll get a new pod:

oc get pod
NAME           READY     STATUS       RESTARTS   AGE
demo-1-build   0/1       ExitCode:0   0          3h
demo-2-9ti4f   1/1       Running      0          3h

Once your new pod is running, try to upload a file again. Does it work? Do you see your file on your master system at /var/export/vol1? You can access your file via this application by going to:

http://demo-php-upload.cloudapps.example.com/uploaded

You should see a directory index of all of the uploaded files and be able to access your file. Neat!