Always ensure a Rancher-vWXYZ transient hostname (rancher#1264)

If a static hostname is not available always set a transient hostname
in the form "Rancher-VWXYZ". Do that also when in recovery mode.

Fixes: rancher/elemental-operator#646

(cherry picked from commit 5e6bc8f)

Signed-off-by: Francesco Giudici <francesco.giudici@suse.com>

framework/files/system/oem/01_elemental-rootfs.yaml

@@ -3,12 +3,7 @@ stages:
   initramfs:
     - if: '[ ! -f /run/cos/recovery_mode ]'
       commands:
-      - |
-        if [ ! -e /usr/local/etc/hostname ]; then
-          mkdir -p /usr/local/etc 
-          echo rancher-${RANDOM} > /usr/local/etc/hostname
-        fi
-        ln -sf /usr/local/etc/hostname /etc/hostname
+        - ln -sf /usr/local/etc/hostname /etc/hostname
     - if: '[ ! -f "/run/cos/recovery_mode" ]'
       name: "Persist /etc/machine-id"
       commands:

framework/files/system/oem/03_hostname.yaml

@@ -0,0 +1,6 @@
+name: "Fallback hostname"
+stages:
+  initramfs:
+    - if: '[ ! -f /etc/hostname ]'
+      commands:
+        - sysctl kernel.hostname=rancher-${RANDOM}