Add locking around all Terraform actions

To prevent them conflicting. Terraform itself has a locking mechanism,
which isn't being used, but this should be sufficient.

1 files changed, 8 insertions, 4 deletions

diff --git a/app/models/backends/terraform_aws/backend_methods.rb b/app/models/backends/terraform_aws/backend_methods.rb
index 52875e6..7489325 100644
--- a/app/models/backends/terraform_aws/backend_methods.rb
+++ b/app/models/backends/terraform_aws/backend_methods.rb
@@ -84,10 +84,14 @@ module Backends::TerraformAws::BackendMethods
   end
 
   def within_backend_terraform_working_directory(&block)
-    TerraformWorkingDirectory.new(
-      terraform_state_id,
-      'terraform/aws/backend'
-    ).within_working_directory(&block)
+    with_advisory_lock(
+      "aws_backend_terraform_working_directory/#{id}"
+    ) do
+      TerraformWorkingDirectory.new(
+        terraform_state_id,
+        'terraform/aws/backend'
+      ).within_working_directory(&block)
+    end
   end
 
   def available_data_snapshots