chore: updated some of the use cases docs

Use Cases/Adding SLURM and MPI to the Compute Node.md

@@ -157,11 +157,11 @@ main(int argc, char **argv)
 {
    int node;
    
-   MPI_Init(&argc,&argv);
+   MPI_Init(&argc, &argv);
    MPI_Comm_rank(MPI_COMM_WORLD, &node);
-     
+   
    printf("Hello World from Node %d\n",node);
-            
+   
    MPI_Finalize();
 }
 ```

Use Cases/Enable WireGuard Security for the `cloud-init-server`.md

@@ -1 +1,83 @@
-When nodes boot in OpenCHAMI, they make a request out to the `cloud-init-server` to retrieve a cloud-init config. The request is not encrypted and can be intercepted and modified.
+When nodes boot in OpenCHAMI, they make a request out to the `cloud-init-server` to retrieve a cloud-init config. The request is not encrypted and can be intercepted and modified.
+
+# Using WireGuard with Cloud-Init
+
+The OpenCHAMI cloud-init metadata server includes a feature to enable a wireguard tunnel **before** running cloud-init.
+## Create a systemd override file for cloud-init
+
+```ini
+[Service]
+PassEnvironment=ochami_wg_ip
+ExecStartPre=/usr/local/bin/ochami-wg-cloud-init-setup.sh
+ExecPostStop=/bin/bash -c "ip link delete wg0"
+```
+
+## Create a Script to Activate WireGuard
+
+```bash
+#!/bin/sh
+set -e -o pipefail
+
+# As configured in systemd, we expect to inherit the "ochami_wg_url" cmdline
+# parameter as an env var. Exit if this is not the case.
+if [ -z "${ochami_wg_ip}" ];
+then
+    echo "ERROR: Failed to find the 'ochami_wg_url' environment variable."
+    echo "It should be specified on the kernel cmdline, and will be inherited from there."
+    if [ -f "/etc/cloud/cloud.cfg.d/ochami.cfg" ];
+    then
+        echo "Removing ochami-specific cloud-config; cloud-init will use other defaults"
+        rm /etc/cloud/cloud.cfg.d/ochami.cfg
+    else
+        echo "Not writing ochami-specific cloud-config; cloud-init will use other defaults"
+    fi
+    exit 0
+fi
+echo "Found OpenCHAMI cloud-init URL '${ochami_wg_ip}'"
+echo "!!!!Starting pre cloud-init config!!!!"
+
+echo "Loading WireGuard kernel mod"
+modprobe wireguard
+
+echo "Generating WireGuard keys"
+wg genkey | tee /etc/wireguard/private.key | wg pubkey > /etc/wireguard/public.key
+
+echo "Making Request to configure wireguard tunnel"
+PUBLIC_KEY=$(cat /etc/wireguard/public.key)
+PAYLOAD="{ \"public_key\": \"${PUBLIC_KEY}\" }"
+WG_PAYLOAD=$(curl -s -X POST -d "${PAYLOAD}" http://${ochami_wg_ip}:27777/cloud-init/wg-init)
+
+echo $WG_PAYLOAD | jq
+
+CLIENT_IP=$(echo $WG_PAYLOAD | jq -r '."client-vpn-ip"')
+SERVER_IP=$(echo $WG_PAYLOAD | jq -r '."server-ip"' | awk -F'/' '{print $1}')
+SERVER_PORT=$(echo $WG_PAYLOAD | jq -r '."server-port"')
+SERVER_KEY=$(echo $WG_PAYLOAD | jq -r '."server-public-key"')
+
+echo "Setting up local wireguard interface"
+echo "Adding wg0 link"
+ip link add dev wg0 type wireguard
+echo "Adding ip address ${CLIENT_IP}/32"
+ip address add dev wg0 ${CLIENT_IP}/32
+echo "Setting the private key"
+wg set wg0 private-key /etc/wireguard/private.key
+echo "Bringing up the wg0 link"
+ip link set wg0 up
+echo "Setting up the peer with the server"
+wg set wg0 peer ${SERVER_KEY} allowed-ips ${SERVER_IP}/32 endpoint ${ochami_wg_ip}:$SERVER_PORT
+rm /etc/wireguard/private.key
+rm /etc/wireguard/public.key
+```
+
+## Add the Scripts to Your Image
+
+```yaml
+copyfiles:
+  - src: '/opt/workdir/images/files/cloud-init-override.conf'
+    dest: '/etc/systemd/system/cloud-init.service.d/override.conf'
+  - src: '/opt/workdir/images/files/ochami-ci-setup.sh'
+    dest: '/usr/local/bin/ochami-ci-setup.sh'
+
+```
+
+## Restart `cloud-init-server` with WireGuard

Use Cases/Serving the Root Filesystem with NFS (import-image.sh).md

@@ -18,3 +18,48 @@ Reload the NFS daemon to apply the changes.
 modprobe -r nfsd && modprobe nfsd
 ```
 
+For NFS, we need to update the /etc/exports file and then reload the kernel nfs daemon
+
+Create `/opt/nfsroot` to serve our images
+
+```bash
+sudo mkdir /srv/nfs
+sudo chown rocky: /srv/nfs
+```
+
+  - Create the `/etc/exports` file with the following contents to export the `/srv/nfs` directory for use by our compute nodes
+    ```bash
+    /srv/nfs *(ro,no_root_squash,no_subtree_check,noatime,async,fsid=0)
+    ```
+
+  - Reload the nfs daemon
+    ```bash
+    sudo modprobe -r nfsd && sudo modprobe nfsd
+    ```
+
+### Webserver for Boot Artifacts
+
+We expose our NFS directory over https as well to make it easy to serve boot artifacts.
+
+```yaml
+# nginx.container
+[Unit]
+Description=Serve /srv/nfs over HTTP
+After=network-online.target
+Wants=network-online.target
+
+[Container]
+ContainerName=nginx
+Image=docker.io/library/nginx:1.28-alpine
+Volume=/srv/nfs:/usr/share/nginx/html:Z
+PublishPort=80:80
+
+[Service]
+TimeoutStartSec=0
+Restart=always
+```
+
+### Import Images from OCI to Share with NFS
+
+[Import-image Script](https://github.com/OpenCHAMI/image-builder/blob/main/scripts/image-import.sh)
+