Create read-only user for postgresql

read-only.sql

CREATE ROLE 'new_username' WITH LOGIN PASSWORD 'new_password' NOSUPERUSER INHERIT NOCREATEDB NOCREATEROLE NOREPLICATION VALID UNTIL 'infinity';
GRANT CONNECT ON DATABASE 'db_name' TO 'new_username';
GRANT USAGE ON SCHEMA public TO 'new_username';
GRANT SELECT ON ALL TABLES IN SCHEMA public TO 'new_username';
GRANT SELECT ON ALL SEQUENCES IN SCHEMA public TO 'new_username';
GRANT EXECUTE ON ALL FUNCTIONS IN SCHEMA public TO 'new_username';