matrix-docker-ansible-deploy/roles/custom/matrix-postgres/templates/sql/init-additional-db-user-and-role.sql.j2

-- `CREATE USER` does not support `IF NOT EXISTS`, so we use this workaround to prevent an error and raise a notice instead.
-- Seen here: https://stackoverflow.com/a/49858797
DO $$
BEGIN
  CREATE USER "{{ additional_db.username }}";
  EXCEPTION WHEN DUPLICATE_OBJECT THEN
  RAISE NOTICE 'not creating user "{{ additional_db.username }}", since it already exists';
END
$$;

-- This is useful for initial user creation (since we don't assign a password above) and for handling subsequent password changes
-- TODO - we should escape quotes in the password.
ALTER ROLE "{{ additional_db.username }}" PASSWORD '{{ additional_db.password }}';

-- This will generate an error on subsequent execution
CREATE DATABASE "{{ additional_db.name }}" WITH LC_CTYPE 'C' LC_COLLATE 'C' OWNER "{{ additional_db.username }}";

-- This is useful for changing the database owner subsequently
ALTER DATABASE "{{ additional_db.name }}" OWNER TO "{{ additional_db.username }}";