Resolve the bug when launching cluster with 0 hosts.

Author: MarcinZablocki

inventory.tpl

@@ -5,7 +5,9 @@ ${bastion_name} ansible_host=${bastion_ip} ansible_user=${bastion_username} role
 ${host} ansible_host=${ip} ansible_user=${compute_username} role=compute
 %{ endfor ~}
 [nfs]
+%{ if nfs != "" }
 ${nfs} ansible_user=${compute_username} role=nfs
+%{ endif }
 [all:children]
 bastion
 compute

playbooks/roles/etc-hosts/tasks/common.yml

@@ -30,7 +30,7 @@
     marker: "# {mark} ANSIBLE MANAGED BLOCK {{ cluster_name }}"
   delegate_to: 127.0.0.1
   run_once: true
-  when: not destroy|bool
+  when: not destroy|bool and groups['compute']|length > 0
 
 - name: add cluster nodes to the /etc/hosts file of the bastion
   blockinfile:
@@ -41,7 +41,7 @@
     marker: "# {mark} ANSIBLE MANAGED BLOCK {{ cluster_name }}"
   delegate_to: 127.0.0.1
   run_once: true
-  when: not destroy|bool
+  when: not destroy|bool and groups['compute']|length > 0
 
 - name: move /etc/hosts on all compute nodes
   become: true