xenapi: Use a jeos vm as a template

DevStack was using templating to speed up the setup process with
XenServer. The template already included some devstack customisations,
not just a clean OS. This change modifies devstack behaviour, so that
the template is a simple clean operating system. This makes it easier to
use custom OS as a template, potentially speeding up the tests.

related to blueprint xenapi-devstack-cleanup

Change-Id: I6cb0a7ed7a90e749b78329a8e2b65fb8b7fcfa5f
diff --git a/tools/xen/install_os_domU.sh b/tools/xen/install_os_domU.sh
index e762f6d..92b1317 100755
--- a/tools/xen/install_os_domU.sh
+++ b/tools/xen/install_os_domU.sh
@@ -167,8 +167,8 @@
 #
 
 GUEST_NAME=${GUEST_NAME:-"DevStackOSDomU"}
-TNAME="devstack_template"
-SNAME_PREPARED="template_prepared"
+TNAME="jeos_template_for_devstack"
+SNAME_TEMPLATE="jeos_snapshot_for_devstack"
 SNAME_FIRST_BOOT="before_first_boot"
 
 function wait_for_VM_to_halt() {
@@ -234,21 +234,8 @@
     vm_uuid=$(xe_min vm-list name-label="$GUEST_NAME")
     xe vm-param-set actions-after-reboot=Restart uuid="$vm_uuid"
 
-    #
-    # Prepare VM for DevStack
-    #
-
-    # Install XenServer tools, and other such things
-    $THIS_DIR/prepare_guest_template.sh "$GUEST_NAME"
-
-    # start the VM to run the prepare steps
-    xe vm-start vm="$GUEST_NAME"
-
-    # Wait for prep script to finish and shutdown system
-    wait_for_VM_to_halt
-
     # Make template from VM
-    snuuid=$(xe vm-snapshot vm="$GUEST_NAME" new-name-label="$SNAME_PREPARED")
+    snuuid=$(xe vm-snapshot vm="$GUEST_NAME" new-name-label="$SNAME_TEMPLATE")
     xe snapshot-clone uuid=$snuuid new-name-label="$TNAME"
 else
     #
@@ -257,6 +244,19 @@
     vm_uuid=$(xe vm-install template="$TNAME" new-name-label="$GUEST_NAME")
 fi
 
+#
+# Prepare VM for DevStack
+#
+
+# Install XenServer tools, and other such things
+$THIS_DIR/prepare_guest_template.sh "$GUEST_NAME"
+
+# start the VM to run the prepare steps
+xe vm-start vm="$GUEST_NAME"
+
+# Wait for prep script to finish and shutdown system
+wait_for_VM_to_halt
+
 ## Setup network cards
 # Wipe out all
 destroy_all_vifs_of "$GUEST_NAME"