reorder the commands so instance starts with a vol attached

.gitlab-ci.yml

@@ -48,8 +48,8 @@ prep-deploy:
            openstack volume snapshot create --volume $prod_volume xdmod-prod-vol-snapshot-$BUILD_DATE
 
            echo "Reattach the prod_volume=${prod_volume} to prod_instance_id=${prod_instance_id} after snapshot is created"
-           openstack server start $prod_instance_id
            openstack server add volume $prod_instance_id $prod_volume --device /dev/vdb
+           openstack server start $prod_instance_id
 
            echo "Make a copy of prod volume $prod_volume to be used in tf-apply"
            TF_VAR_data_volume="xdmod-prod-vol-$BUILD_DATE"