make include_modules="postgres"

$ createdb ser
$ psql -U postgres ser
ser=# CREATE TABLE subscriber (
 username varchar(32),
 domain varchar(32),
 password varchar(16),
 PRIMARY KEY (username, domain)
);
ser=# create user ser with password 'mypass';
ser=# grant all on table subscriber to ser;

ser=# insert into subscriber values ('user', 'domain_or_realm', 'pass');

loadmodule "/usr/lib/ser/modules/postgres.so"
loadmodule "/usr/lib/ser/modules/usrloc.so"
loadmodule "/usr/lib/ser/modules/auth.so"
loadmodule "/usr/lib/ser/modules/auth_db.so"
modparam("usrloc", "db_mode", 0) # not using postgresql for usrloc database, in memory only
modparam("auth_db", "calculate_ha1", 1)
modparam("auth_db", "password_column", "password")
modparam("auth_db","db_url", "sql://ser:mypass@localhost:5432/ser")

modparam("auth_db","db_url", "postgres://ser:mypass@localhost:5432/ser")