Verify that neither the Swift container or Mistral environment exist

Without this check it is possible for create plan to get into a
partial state. If the Mistral environment exists, but the swift
container doesn't then it will create the container and error
when attempting to create the environment. There is still a
possibility of a race condition, but this verification greatly
reduces that risk.

Change-Id: I18dee67c5935248a32b3b90241e3bbdd02034677
Closes-Bug: 1613196

workbooks/plan_management.yaml

@@ -46,6 +46,23 @@ workflows:
       - container
       - queue_name: tripleo
     tasks:
+
+      verify_container_doesnt_exist:
+        action: swift.head_container container=<% $.container %>
+        on-success: notify_zaqar
+        on-error: verify_environment_doesnt_exist
+        publish:
+          status: FAILED
+          message: "Unable to create plan. The Swift container already exists"
+
+      verify_environment_doesnt_exist:
+        action: mistral.environments_get name=<% $.container %>
+        on-success: notify_zaqar
+        on-error: create_container
+        publish:
+          status: FAILED
+          message: "Unable to create plan. The Mistral environment already exists"
+
       create_container:
         action: tripleo.create_container container=<% $.container %>
         on-success: upload_to_container