Create read-only user/role in Postgres.

gistfile1.sql

# create user
create role myuser login password 'somepassword';
grant connect on database events to myuser;
grant usage on schema public to myuser;

# privs on current stuff
grant select on all tables in schema public to myuser;
grant select on all sequences in schema public to myuser;
grant execute on all functions in schema public to myuser;

# privs on future stuff
alter default privileges in schema public grant select on tables to myuser;
alter default privileges in schema public grant select on sequences to myuser;
alter default privileges in schema public grant execute on functions to myuser;