Grant privileges on future tables in PostgreSQL?

It looks like the solution is to alter default privileges for backup user:

alter default privileges in schema public grant all on tables to backup;
alter default privileges in schema public grant all on sequences to backup;

From the comment by Matt Schaffer:

As caveat, the default only applies to the user that executed the
alter statement. This confused me since I was driving most of my
permissions statements from the postgres user but creating tables from
an app user. In short, you might need something like this depending on
your setup:

ALTER DEFAULT PRIVILEGES FOR USER webapp IN SCHEMA public GRANT SELECT ON SEQUENCES TO backup;
ALTER DEFAULT PRIVILEGES FOR USER webapp IN SCHEMA public GRANT SELECT ON TABLES TO backup;

Where webapp is the user that will be creating new tables in the futrue and backup is the user that will be able to read from new tables created by webapp.