Removing the extra closing parentheses.

Adding true to the default filter and moving paren.

roles/openshift_logging/defaults/main.yml

@@ -1,7 +1,7 @@
 ---
 openshift_logging_use_ops: False
 openshift_logging_master_url: "https://kubernetes.default.svc.{{ openshift.common.dns_domain }}"
-openshift_logging_master_public_url: "{{ 'https://' + openshift_master_cluster_public_hostname | default(openshift.common.public_hostname) + ':' ~ openshift_master_api_port) }}"
+openshift_logging_master_public_url: "{{ 'https://' + openshift_master_cluster_public_hostname | default(openshift.common.public_hostname, true) + ':' ~ openshift_master_api_port }}"
 openshift_logging_nodeselector: null
 openshift_logging_labels: {}
 openshift_logging_label_key: ""