CPD-7592 keep standard tags when updating

Change: patch
Purpose: maintenance

lib/moonshot/stack.rb

@@ -39,6 +39,7 @@ def update(dry_run:, force:)
       raise "No stack found #{@name.blue}!" unless stack_exists?
 
       change_set = ChangeSet.new(new_change_set, @name)
+
       wait_for_change_set(change_set)
       return unless change_set.valid?
 
@@ -94,6 +95,12 @@ def outputs
         .to_h
     end
 
+    def existing_tags
+      get_stack(@name)
+        .tags
+        .map { |o| { key: o.key, value: o.value } }
+    end
+
     def exists?
       cf_client.describe_stacks(stack_name: @name)
       true
@@ -235,6 +242,7 @@ def new_change_set
         parameters: @config.parameters.values.map(&:to_cf),
         tags: make_tags
       }
+
       if @config.template_s3_bucket
         parameters[:template_url] = upload_template_to_s3
       else
@@ -301,7 +309,7 @@ def make_tags
         default_tags << { key: @config.additional_tag, value: @name }
       end
 
-      default_tags + @config.extra_tags
+      (default_tags + @config.extra_tags + existing_tags).uniq!
     end
 
     def format_event(event)