Don't provision databases in sandbox unless needed

playbooks/edx_sandbox.yml

@@ -30,9 +30,11 @@
       - xqueue
       nginx_default_sites:
       - lms
-    - mysql
+    - role: mysql
+      when: EDXAPP_MYSQL_HOST == 'localhost'
     - edxlocal
-    - mongo
+    - role: mongo
+      when: "'localhost' in EDXAPP_MONGO_HOSTS"
     - { role: 'edxapp', celery_worker: True }
     - edxapp
     - notifier
@@ -43,7 +45,8 @@
     - oauth_client_setup
     - { role: 'rabbitmq', rabbitmq_ip: '127.0.0.1' }
     - oraclejdk
-    - elasticsearch
+    - role: elasticsearch
+      when: "'localhost' in EDXAPP_ELASTIC_SEARCH_CONFIG|map(attribute='host')"
     - forum
     - { role: notifier, NOTIFIER_DIGEST_TASK_INTERVAL: "5" }
     - { role: "xqueue", update_users: True }