Fix node label customisation (#679)

* node labels: add checks for custom labels

- README: add more info about customising labels
- pre_tasks: add checks for label values, set to empty dict if undefined
- group_vars: move labels customisation from OSEv3 to all

* pre_tasks: tried a new approach to updating variables

* pre_tasks: variable update fixed

* pre_tasks: rollback upscaling changes (to be added in upscaling PR)

* pre_tasks: blank line removed

* pre_tasks: add check for undefined variable (should not happen though)

* pre_tasks: be sure to have regions defined

1 files changed, 9 insertions, 1 deletions

diff --git a/playbooks/provisioning/openstack/README.md b/playbooks/provisioning/openstack/README.md
index 002c2f6aa..c9f651032 100644
--- a/playbooks/provisioning/openstack/README.md
+++ b/playbooks/provisioning/openstack/README.md
@@ -130,7 +130,15 @@ The `openstack_num_masters`, `openstack_num_infra` and
 App nodes to create.
 
 The `openshift_cluster_node_labels` defines custom labels for your openshift
-cluster node groups, like app or infra nodes. For example: `{'region': 'infra'}`.
+cluster node groups. It currently supports app and infra node groups.
+The default value of this variable sets `region: primary` to app nodes and
+`region: infra` to infra nodes.
+An example of setting a customised label:
+```
+openshift_cluster_node_labels:
+  app:
+    mylabel: myvalue
+```
 
 The `openstack_nodes_to_remove` allows you to specify the numerical indexes
 of App nodes that should be removed; for example, ['0', '2'],