How to stop all mutations temporarily for infrastructure migration?

[orestesgaolin]

We're planning a migration of underlying database infrastructure for our Hasura project as well as migration of the Hasura instance from one region to another.

We would like to keep the primary instance available for read but prevent all the mutations from happening so that when the secondary instance is available, all pending mutations from the client app will be applied. Our client is able to retry failed mutations so blocking them is not an issue. We also keep the Hasura instance behind a custom domain, so once DNS gets updated users should get connected to the secondary instance.

We considered shutting down the primary instance of Hasura but there are some queries that we would like to stay available during migration.

Is there a way to globally disable all the mutations? For now the only way I can see to achieve it is to modify Hasura metadata such that all the user role permissions for inserts and updates get removed, hence disallowing any mutations to get executed.