Create PSQL User and give read access to it to all tables in all schemas

createUser.sql

CREATE USER "someuser" WITH PASSWORD 'somepassword';
GRANT india_group TO "someuser";
GRANT "prateekthakore" TO "sharad.sachdeva";

GRANT CONNECT ON DATABASE somedatabase TO "someuser"

DO $do$
DECLARE
    theSchema text;
BEGIN
    FOR theSchema IN SELECT DISTINCT table_schema FROM information_schema.tables
    LOOP
        EXECUTE format($$ GRANT USAGE ON SCHEMA %I TO "someUser" $$, theSchema);
        EXECUTE format($$ GRANT SELECT ON ALL SEQUENCES IN SCHEMA %I TO "someUser" $$, theSchema);
        EXECUTE format($$ GRANT SELECT ON ALL TABLES IN SCHEMA %I TO "someUser" $$, theSchema);
    END LOOP;
END;
$do$;