How to create read only user in PostgreSQL

read-access.sql

-- Create a group
CREATE ROLE readaccess;

-- Grant access to existing tables
GRANT CONNECT ON DATABASE _database_name_ TO readaccess;
GRANT USAGE ON SCHEMA public TO readaccess;
GRANT SELECT ON ALL TABLES IN SCHEMA public TO readaccess;
GRANT USAGE, SELECT ON ALL SEQUENCES IN SCHEMA public TO readaccess;

-- Grant access to future tables
ALTER DEFAULT PRIVILEGES IN SCHEMA public GRANT SELECT ON TABLES TO readaccess;

-- Create a final user with password
CREATE USER readonly WITH ENCRYPTED PASSWORD '_secret_' NOSUPERUSER INHERIT NOCREATEDB NOCREATEROLE NOREPLICATION VALID UNTIL 'infinity';
GRANT readaccess TO readonly;

readonly.sql

-- Create a final user with password
CREATE USER readonly WITH ENCRYPTED PASSWORD '_secret_' NOSUPERUSER INHERIT NOCREATEDB NOCREATEROLE NOREPLICATION VALID UNTIL 'infinity';

-- Grant access to existing tables
GRANT CONNECT ON DATABASE _database_name_ TO readonly;
GRANT USAGE ON SCHEMA public TO readonly;
GRANT SELECT ON ALL TABLES IN SCHEMA public TO readonly;
GRANT USAGE, SELECT ON ALL SEQUENCES IN SCHEMA public TO readonly;

-- Grant access to future tables
ALTER DEFAULT PRIVILEGES IN SCHEMA public GRANT SELECT ON TABLES TO readonly;