Add doc for external storage provider.

docs/storage-external-block.md

@@ -0,0 +1,52 @@
+# External Block - Bring Your Own Storage 
+
+For some Topo/Ceph/NFS are not great fits, Genestack allows for external block devices to be used in the stand up and operation of Openstack. 
+
+##  Deploy External CSI driver in Genestack
+
+Follow Documentation on getting a storage class presented to k8s, name it "general" and mark that storage class as default, in this example storage is provided by democratic csi driver over iscsi.
+
+``` shell
+(genestack) root@genestack-controller1:/opt/genestack/submodules/openstack-helm# kubectl get sc
+NAME                   PROVISIONER                     RECLAIMPOLICY   VOLUMEBINDINGMODE   ALLOWVOLUMEEXPANSION   AGE
+general (default)      org.democratic-csi.iscsi        Delete          Immediate           true                   3h15m
+```
+
+!!! info
+
+    OSD placement is done on nodes with label ‘openstack-control-plane’, a minimum of 3 nodes is required for a healthy Ceph cluster.
+
+Deploy Ceph operator 
+
+``` shell
+kubectl apply -k /opt/genestack/kustomize/rook-operator/
+```
+
+Deploy Ceph on PVC
+
+``` shell
+kubectl apply -k /opt/genestack/kustomize/rook-cluster-external-pvc/
+```
+
+Monitor cluster state, once cluster HEALTH_OK proceed to the next step
+
+``` shell
+(genestack) root@genestack-controller1:/opt/genestack/submodules/openstack-helm# kubectl --namespace rook-ceph get cephclusters.ceph.rook.io
+NAME        DATADIRHOSTPATH   MONCOUNT   AGE    PHASE   MESSAGE                        HEALTH      EXTERNAL   FSID
+rook-ceph   /var/lib/rook     3          129m   Ready   Cluster created successfully   HEALTH_OK              9a6657cd-f3ab-4d70-b276-a05e2ca03e1b
+```
+
+Deploy cephfs filesystem named 'general-multi-attach' for Glance consumption
+
+``` shell
+kubectl apply -k /opt/genestack/kustomize/rook-defaults-external-pvc/
+```
+
+You should now have two storage class providers configured for Genestack
+
+``` shell 
+(genestack) root@genestack-controller1:/opt/genestack/submodules/openstack-helm# kubectl get sc -A
+NAME                   PROVISIONER                     RECLAIMPOLICY   VOLUMEBINDINGMODE   ALLOWVOLUMEEXPANSION   AGE
+general (default)      org.democratic-csi.iscsi        Delete          Immediate           true                   3h25m
+general-multi-attach   rook-ceph.cephfs.csi.ceph.com   Delete          Immediate           true                   85m
+```