Fix empty nodelist in ondemand apps (#861)

* fix empty nodelist in ondemand apps (reqd. when using topology)

* enable topology in CI

Author: sjpb

environments/.stackhpc/inventory/extra_groups

@@ -40,3 +40,6 @@ cluster
 
 [compute_init:children]
 compute
+
+[topology:children]
+compute

environments/common/inventory/group_vars/all/openondemand.yml

@@ -158,7 +158,9 @@ openondemand_apps_desktop_default:
       native:
         - <%= "--nodes=1" %>
         - <%= "--ntasks=#{num_cores}" %>
+        <% if node != '' %>
         - <%= "--nodelist=#{node}" %>
+        <% end %>
         <% if gres != 'none' %>
         - <%= "--gres=#{gres}:#{gres_count}" %>
         <% end %>
@@ -218,7 +220,9 @@ openondemand_apps_jupyter_default:
       native:
         - <%= "--nodes=1" %>
         - <%= "--ntasks=#{num_cores}" %>
+        <% if node != '' %>
         - <%= "--nodelist=#{node}" %>
+        <% end %>
         <% if gres != 'none' %>
         - <%= "--gres=#{gres}:#{gres_count}" %>
         <% end %>