Create a standard user for a RDS DB instance running PostgreSQL

create_standard_postgres_rds.md

Create standard role

CREATE ROLE api;   

Grant access to all existing tables/sequences/functions

GRANT ALL PRIVILEGES ON SCHEMA public to api;
GRANT ALL ON ALL TABLES IN SCHEMA public to api;
GRANT ALL ON ALL SEQUENCES IN SCHEMA public to api;
GRANT ALL ON ALL FUNCTIONS IN SCHEMA public to api;

Create user and grant role to this user

CREATE ROLE user_api WITH PASSWORD 'password' LOGIN;   
GRANT api TO user_api;

Login as user_api and grant all privileges on future tables/sequences/functions

ALTER DEFAULT PRIVILEGES FOR ROLE postgres IN SCHEMA public GRANT ALL ON TABLES TO api;
ALTER DEFAULT PRIVILEGES FOR ROLE postgres IN SCHEMA public GRANT ALL ON SEQUENCES TO api;
ALTER DEFAULT PRIVILEGES FOR ROLE postgres IN SCHEMA public GRANT ALL ON FUNCTIONS TO api;