Merge pull request #3605 from nhsuk/development_backup

Enable vault backups for Preview

Author: bogsi17

terraform/app/env/preview.tfvars

@@ -27,3 +27,5 @@ http_hosts = {
 appspec_bucket       = "nhse-mavis-appspec-bucket-preview"
 minimum_web_replicas = 2
 maximum_web_replicas = 4
+
+enable_backup_to_vault = true