Add FAQ entry for persistent volume using OCI FSS (#1425)

* Add FAQ entry for persistent volume using OCI FSS

* Update init container command and FAQ text per review

* Update oci-fss-pv.md

* update the \magic command

* fix magic command

* Update init container command with extra bullet proof syntax

* Update init container command properly this time!

Co-authored-by: Mark Nelson <[email protected]>

Author: TheFrogPad

docs-source/content/faq/oci-fss-pv.md

@@ -0,0 +1,97 @@
+---
+title: "Using OCI File Storage (FSS) for Persistent Volumes"
+date: 2020-02-12T12:12:12-05:00
+draft: false
+weight: 6
+---
+
+If you are running your Kubernetes cluster on Oracle Container Engine 
+for Kubernetes (commonly known as OKE), and you use OCI File Storage (FSS)
+for persistent volumes to store the WebLogic domain home, then the file system
+handling demonstrated in the operator persistent volume sample will require
+an update to properly initialize the file ownership on the persistent volume
+when the domain is initially created.
+
+{{% notice note %}}
+File permission handling on persistent volumes can differ between
+cloud providers and even with the underlying storage handling on
+Linux based systems. These instructions provide one option to
+update file ownership used by the standard Oracle images where
+UID `1000` and GID `1000` typically represent the `oracle` or `opc` user.
+For more information on persistent volume handling,
+see [Persistent storage]({{< relref "/userguide/managing-domains/persistent-storage/_index.md" >}}).
+{{% /notice %}}
+
+
+### Failure during domain creation with persistent volume sample
+
+The existing sample for [creation of a domain home on persistent volume](https://github.com/oracle/weblogic-kubernetes-operator/tree/master/kubernetes/samples/scripts/create-weblogic-domain/domain-home-on-pv)
+uses a Kubernetes job to create the domain. The sample uses an
+`initContainers` section to change the file ownership which will
+fail for OCI FSS created volumes used with an OKE cluster.
+
+The OCI FSS volume contains some files that are not modifiable thus
+causing the Kubernetes job to fail. The failure is seen in the
+description of the Kubernetes job pod:
+```bash
+$ kubectl describe -n domain1-ns pod domain1-create-weblogic-sample-domain-job-wdkvs
+   :
+   :
+Init Containers:
+  fix-pvc-owner:
+    Container ID:  docker://7051b6abdc296c76e937246df03d157926f2f7477e63b6af3bf65f6ae1ceddee
+    Image:         container-registry.oracle.com/middleware/weblogic:12.2.1.3
+    Image ID:      docker-pullable://container-registry.oracle.com/middleware/weblogic@sha256:47dfd4fdf6b56210a6c49021b57dc2a6f2b0d3b3cfcd253af7a75ff6e7421498
+    Port:          <none>
+    Host Port:     <none>
+    Command:
+      sh
+      -c
+      chown -R 1000:1000 /shared
+    State:          Terminated
+      Reason:       Error
+      Exit Code:    1
+      Started:      Wed, 12 Feb 2020 18:28:53 +0000
+      Finished:     Wed, 12 Feb 2020 18:28:53 +0000
+    Ready:          False
+    Restart Count:  0
+    Environment:    <none>
+
+   :
+```
+
+### Updating the domain on persistent volume sample
+In the following snippet of the [create-domain-job-template.yaml](https://github.com/oracle/weblogic-kubernetes-operator/blob/master/kubernetes/samples/scripts/create-weblogic-domain/domain-home-on-pv/create-domain-job-template.yaml),
+you can see the updated `command` for the init container:
+```
+apiVersion: batch/v1
+kind: Job
+metadata:
+  name: %DOMAIN_UID%-create-weblogic-sample-domain-job
+  namespace: %NAMESPACE%
+spec:
+  template:
+    metadata:
+  :
+  :
+    spec:
+      restartPolicy: Never
+      initContainers:
+        - name: fix-pvc-owner
+          image: %WEBLOGIC_IMAGE%
+          command: ["sh", "-c", "chown 1000:1000 %DOMAIN_ROOT_DIR%/. && find %DOMAIN_ROOT_DIR%/. -maxdepth 1 ! -name '.snapshot' ! -name '.' -print0 | xargs -r -0 chown -R 1000:1000"]
+          volumeMounts:
+          - name: weblogic-sample-domain-storage-volume
+            mountPath: %DOMAIN_ROOT_DIR%
+          securityContext:
+            runAsUser: 0
+            runAsGroup: 0
+      containers:
+        - name: create-weblogic-sample-domain-job
+          image: %WEBLOGIC_IMAGE%
+
+  :
+```
+Use this new `command` in your copy of this template file. This will result in
+the ownership being updated for the expected files only, before the WebLogic
+domain is created on the persistent volume.