different scheme for defaults

playbooks/secure_example/vars/sandbox_custom.yml

@@ -4,8 +4,12 @@
 # cms_nginx_port: 80
 # lms_preview_nginx_port: 80
 # Override LMS_BASE and PREVIEW_LMS_BASE in the cms env config
+
+# These should be overridden with the -e option on the command line
+lms_base: ''
+preview_lms_base: ''
 cms_env_config:
-  'LMS_BASE': '{% set lms_base=lms_base or ""%}{{lms_base}}'
+  'LMS_BASE': '{{ lms_base }}'
   'MITX_FEATURES':
-    'PREVIEW_LMS_BASE': '{% set preview_lms_base=preview_lms_base or ""%}{{preview_lms_base}}'
+    'PREVIEW_LMS_BASE': '{{ preview_lms_base }}'